A concrete scan is priced by the job, not by a fixed rate per slab. The total depends on how much area you need cleared, how many locations there are, how hard the site is to reach, which method is used and what you want handed back (spray marks on the slab, photos or a written report). We don’t publish a flat scanning price, because two jobs that look alike on paper can differ a lot on site. This guide shows you what sits behind a quote, so you can compare quotes properly and budget with confidence.

TL;DR

• Scanning is quoted per job. Area, number of locations, access, method and reporting are the main price drivers.
• Ground penetrating radar (GPR) is the usual method for slabs and walls before cutting or coring. X-ray is a specialist option with extra licensing and safety controls.
• A scan is a small line in a budget compared with striking rebar, a conduit or a post-tension cable.
• When you compare quotes, check what is marked on the slab, what depth the operator can reliably read and whether the scan is bundled with the cutting or coring.
• Vic Sawing & Drilling scans and cuts across Melbourne and Victoria, and we quote free.

Table of Contents

• What a concrete scan is and why it gets a line in the budget
• How concrete scanning is priced
• What affects the cost of scanning a slab
• Quote scenarios to help you budget
• GPR versus X-ray: how the cost compares
• What the scan will and will not tell you
• Getting a quote you can compare
• Preparing the site so the scan is quick
• Our perspective
• Concrete scanning and cutting from Vic Sawing & Drilling
• FAQ
• Sources

What a concrete scan is and why it gets a line in the budget

A concrete scan locates what is inside a slab or wall before anyone cuts, drills or cores it. That usually means reinforcing bars, electrical conduit, pipes and, in some buildings, post-tension cables. The operator marks the findings on the surface so the cut or core can be placed clear of them.

You are paying for risk control. Hitting a conduit can mean a power outage and a repair. Cutting a tensioned cable can damage the structure and put people at risk. Hitting rebar with a core bit wears out diamond segments and stalls the job. Our guide on how to avoid rebar when drilling concrete covers what that looks like on a real job, and our piece on why GPR concrete scanning matters explains the technology in more detail.

How concrete scanning is priced

Operators price a scan in one of three ways, and many combine them.

1. A minimum call-out. Small jobs, such as scanning for two or three cores in an office slab, usually carry a minimum charge that covers travel, setup and a short time on site. The cost per hole is highest on very small jobs for this reason.
2. Time on site. Larger or more complex jobs are often priced by the hour, half day or full day, with the operator’s time and the scanner included.
3. Area or location count. Some quotes are built from the number of slabs, walls or grid areas to scan, which suits repeated work such as a floor-by-floor fit-out.

A fourth path is bundling. When the scan is followed by cutting or coring by the same crew, the scan is often folded into the job price. On our own work, a scan before cutting or coring is part of the planning, and we are happy to explain in the quote what is included. Our published starting range for concrete cutting is $450 to $5,000 per one-off job, which gives you a sense of how the work around a scan is scaled. Scanning itself is quoted to your site.

What affects the cost of scanning a slab

These are the factors that move a quote up or down, in rough order of impact.

Area and number of locations

Scanning a 1 m² patch for a single core is a different task from mapping a whole warehouse floor before saw cuts. More area means more passes in a grid pattern, more marking and more time. Several separate locations in one building add walking, setup and access time.

Access and site conditions

A clear ground-floor slab is quick. A ceiling, a wall behind shelving, a plant room or a basement with limited lighting takes longer. Rough, wet or heavily finished surfaces such as thick coatings, tiles or screeds can slow the work. Tight spaces affect the cutting and drilling stage too, which we cover in concrete drilling in tight spaces.

Depth and density of what is inside

Heavily reinforced slabs, double mesh layers, closely spaced bars and thick structural slabs are harder to read than a light residential slab on ground. Depth matters because the accuracy of any scanner falls as the target gets deeper. As one example of published figures, the Hilti PS 1000 X-Scan lists a depth accuracy of ±10 mm for targets under 100 mm and ±15% beyond that, a localization accuracy of ±10 mm, and a minimum distance of 40 mm between two neighboring objects. Those are specifications for one product, not a promise for every site, but they show why the operator keeps cutting lines a safe margin away from marked objects.

Method

GPR is the standard for most slab and wall work. X-ray imaging is used for specific situations and carries additional compliance costs, covered below.

Reporting and deliverables

Spray or chalk marks on the surface are the baseline. If you also need annotated photos, a marked-up plan or a written record for an engineer or building certifier, expect that to add time to the quote. Tell the operator at the start who will use the results.

Timing and urgency

After-hours work in occupied buildings, same-day bookings and work in busy live sites change the price. If you can book ahead and give a clear window, you give the operator room to schedule efficiently.

Travel

Melbourne metro jobs and regional Victoria jobs travel differently. If you are outside the city, the quote may include travel time. We service Melbourne and all of Victoria, including Richmond, Werribee, Sunbury and Cranbourne.

Quote scenarios to help you budget

The table shows how the factors combine on typical jobs. It describes what drives cost, not a price list.

The quickest way to pull your own cost down is to give accurate information up front: photos, the slab type if you know it, any drawings and the exact positions you want to cut or core.

GPR versus X-ray: how the cost compares

Most clients ask about X-ray because they have heard it gives a clearer picture. It is a legitimate method, but it is used for a narrower set of situations, and it brings regulation with it.

GPR sends radar pulses into the concrete from one side and reads the reflections. It is portable, quick and does not use ionizing radiation, which is why it is the default for slabs, walls and columns before cutting and coring. X-ray imaging passes radiation through the member and needs access to both sides, with an exclusion zone around the work and trained, licensed operators.

That licensing is a real cost behind the method. For reference, the NSW EPA lists radiation user licence fees for Group 3 regulated material, which includes radiation apparatus used for industrial radiography, at $295 for a 1-year licence and $607 for a 3-year licence, with a further $276 fee for non-standard applications referred to the Radiation Advisory Council. That is the New South Wales schedule. Other states set their own arrangements, so if X-ray is on the table for a Victorian job, ask the operator to confirm the licensing and safety plan that applies.

In plain terms, X-ray work is typically priced above GPR work because of equipment, licensing, safety controls and the need for access to both sides. Our comparison, GPR vs X-ray in Australia, walks through which method fits which situation. For routine pre-cut scanning, GPR gives you the information the crew needs at a lower cost and with less disruption on site.

What the scan will and will not tell you

A good scan answers specific questions: where the top layer of reinforcement runs, where conduits sit, whether post-tension cables are present and, within the limits of the method, how deep things are. It is a planning tool, and the operator reads the result with the construction type in mind.

There are practical limits to keep in mind when budgeting:

• Accuracy declines with depth, as the published specifications above show.
• Closely spaced objects can blur together, so the operator keeps clearance from marked lines.
• Wet concrete and dense reinforcement make interpretation harder, and the operator may need more time or a second method.
• The scan shows what is in the area scanned. If your cut line or core position moves, ask for the new position to be scanned as well.

This is why we plan scanning and cutting together: the person who marks the slab is working with the crew who will make the cut.

Getting a quote you can compare

When you collect two or three quotes, line them up on the same basis. Ask each operator:

1. What area and how many locations are covered? A lower price for a smaller area is not cheaper.
2. What is marked on the slab, and what will you receive afterward? Surface marks only, photos or a written record.
3. Is the scan bundled with the cutting or coring? If so, is it itemized.
4. What is the minimum charge and what happens if the job runs over?
5. Who holds the licences and insurances, and what is the safety plan? For OH&S, you want to see licensed, qualified operators following safe work procedures.
6. What access do they need? Power, lighting, clear floor, both sides of a wall.
7. How soon can they start, and is after-hours work available?

For wider budgeting on a cutting or demolition project, our Melbourne concrete removal cost and quote checklist covers waste rules and the line items to look for. Coring is commonly priced per core, and a breakdown of coring unit prices by slab shows why a single rate rarely fits every slab, which is exactly why we ask about your slab before giving a number.

Preparing the site so the scan is quick

Preparation is the cheapest way to trim a scanning bill, because time on site is the main variable. Before the operator arrives:

• Clear the area. Move furniture, stock and equipment away from the slab or wall.
• Mark your intended positions. A simple sketch or tape marks showing where you want to cut or core saves back-and-forth.
• Gather drawings. Structural or services plans help the operator cross-check what the scan shows.
• Confirm access and power. Lift access, parking, loading dock times and building induction requirements.
• Tell us about the structure. If you know a slab is suspended, post-tensioned or recently renovated, say so.

If you manage a building, tell the operator about tenants, noise limits and hours at the time of booking so the work is scheduled around them.

Our perspective

We see the cost of scanning from the other end of the job: the crew that has to make the cut. A scan that is rushed or skipped rarely saves money. It moves the cost to a damaged conduit, a stalled core bit or a redesigned opening.

That is why we treat scanning as the first step of the cutting and drilling process rather than a separate product. Our licensed and qualified operators follow OH&S safety standards, and we use modern equipment on everything from a single domestic core to large commercial and industrial projects. When the person who scans the slab is working with the team that will cut it, the markings fit the method, the cut lines are placed with the right clearances and fewer questions are left for the day of the job.

We would rather give you a clear quote on the scope than a number that looks low and grows later. Tell us what you are cutting, where and why, and we will explain what the scan covers and what comes after it.

MYBMC

Concrete scanning and cutting from Vic Sawing & Drilling

If you are planning a cut, core or removal in Melbourne or anywhere in Victoria, we can scan the slab and carry out the work with the same crew. We service homeowners, contractors, property managers, engineers and industrial sites, and we quote free.

Send us the location, the slab or wall type if you know it and the openings you need. We will explain what is included in the scan and the work that follows.

See our concrete scanning service for how we work, or go straight to core drilling and wall sawing if you already know what you need. You can also start from our home page to request a quote.

FAQ

How much does a concrete scan cost in Melbourne?

It depends on the area, number of locations, access, method and reporting, so scans are quoted per job. Small jobs usually carry a minimum call-out, and larger jobs are priced by time on site or by area. We provide free quotes, and the more detail you give us, the tighter the number.

Is concrete X-ray scanning more expensive than GPR?

Generally yes. X-ray needs access to both sides, an exclusion zone, trained licensed operators and a safety plan, all of which add to the cost. GPR is portable and suits most slabs and walls before cutting or coring.

Do I need a scan before coring a small hole?

Yes, it is good practice for any hole in a slab or wall, however small. A scan locates reinforcement, conduit and, in some structures, post-tension cables, so the core can be placed clear of them. It is quick on small jobs and avoids a much larger repair.

Is a scan cheaper when booked with cutting or coring?

Often, yes. One crew, one mobilization and one set of access arrangements keep time on site down. Ask for the scan to be shown as a line in the quote so you can see what is included.

Can I scan my own slab with a hired scanner?

Scanners are specialist instruments, and reading the results takes training and experience with different slab types. For anything that will be cut or cored, we recommend having a licensed, qualified operator scan and mark it, then carry out the work as one planned job.

Sources

• Radiation user licence fees, NSW EPA
• PS 1000 X-Scan concrete scanner specifications, Hilti Australia

Recommended

• Concrete Scanning Melbourne: Concrete Scanning
• $50–$150/m2 Melbourne Concrete Removal: Waste Rules & Quote Checklist
• Concrete Removal & Demolition Melbourne

A good core drilling contractor scans the concrete before any bit touches it, works to a site-specific safety plan, and can explain in plain terms how each hole will be drilled, cooled, cleaned up and signed off. If a contractor can do those three things, the hole itself is the easy part. This guide covers what to ask, what to expect on site, how slab edges are handled and what drives the quote, so you can hire with confidence whether you manage a commercial fit-out or a home renovation.

TL;DR

• Hire for process, not just the drill: scanning for reinforcement and services, a written safety plan, wet cutting or dust extraction, and clear sign-off.
• In Victoria, an SWMS must be prepared before high-risk construction work, and many head contractors add their own permit and hold-point rules.
• Holes near slab edges need the position, diameter and reinforcement checked before drilling, and often an engineer’s input.
• Cost depends on hole size, depth, access, number of holes and scanning, so a site-specific quote beats any per-hole figure.
• Tell your contractor the purpose of every hole up front. It shapes the bit, the method and the paperwork.

Table of Contents

• What core drilling contractors actually do
• How to choose a core drilling contractor
• How a core hole is planned and drilled
• Core drilling near slab edges
• Safety rules that apply in Victoria
• What affects cost and timing
• How the job differs by project type
• Our perspective on hiring a core drilling contractor
• Get a quote from Vic Sawing & Drilling
• FAQ
• Sources

What core drilling contractors actually do

Core drilling cuts clean, round holes through concrete using a diamond-tipped hollow bit, which leaves a solid cylinder (the core) that is removed. Contractors use it wherever something has to pass through a slab or wall: plumbing and drainage penetrations, electrical and data risers, HVAC and exhaust openings, hold-down and anchor holes, and inspection or sampling points.

The same crews often handle the work around the hole. On many projects core drilling sits next to concrete scanning, wall sawing, wire sawing and concrete removal, because a service opening, a doorway and a slab cut-out are often part of the same package. A contractor who offers several methods can match the method to the job instead of forcing every job through a core bit.

Common uses we see across Melbourne and Victoria:

• Services penetrations: pipes, conduits and cable trays through floors and walls in new and existing buildings.
• Risers and chases: vertical and horizontal runs that connect floors.
• Ventilation and exhaust: large-diameter holes for fans, ducts and kitchen extraction.
• Anchor and fixing holes: for handrails, machinery, clotheslines, signage posts and similar items.
• Structural and testing work: cores taken for assessment, where an engineer specifies the location and size.

If you want the full detail of our own service, see our core drilling page. For jobs that involve larger or deeper holes in ground or heavy structures, our rock drilling and industrial drilling service covers that scope.

How to choose a core drilling contractor

Price matters, but the checks below separate a smooth job from one that stalls on site or damages a structure. Ask each contractor the same questions and compare the answers.

1. Do they scan before they drill?

Slabs and walls hide reinforcement, conduits, pipes and, in many buildings, post-tensioned cables. Hitting a post-tensioned cable is a serious structural and safety event, so scanning is not an optional extra. Ground penetrating radar (GPR) is the common method for mapping what sits inside the concrete. Our article on the importance of GPR concrete scanning explains what the scan shows, and seven checks before drilling walks through what a careful crew confirms first.

Ask: who scans, what is scanned (the full footprint of each hole plus a margin, not just a centerpoint), and how locations are marked on the surface.

2. Will they provide a site-specific SWMS?

WorkSafe Victoria’s industry standard on safe concrete cutting and drilling states that a Safe Work Method Statement must be prepared before high-risk construction work, including work on or near electrical installations or services. A generic, copy-and-paste document is a warning sign. The SWMS should name your site, the hazards that apply to it and the controls the crew will use. We cover what to look for in six questions to ask about SWMS for concrete cutting.

3. How do they control dust and slurry?

Cutting and drilling concrete releases respirable crystalline silica unless it is controlled. SafeWork NSW’s code of practice on cutting, drilling and grinding concrete says contractors should use water suppression or dust extraction, required PPE and respiratory protection, and exclusion zones. WorkSafe Victoria’s standard adds that wet methods should supply enough water, that extraction can remove dust at the source, and that slurry should be removed before it dries.

This matters for your site too. Slurry in a carpeted office, a basement carpark or a finished home is a cleaning and drainage problem. Ask how water is contained and collected, and how the area is left.

4. Are the operators trained and the equipment maintained?

The same SafeWork NSW code expects suitable, maintained equipment run by trained and competent workers. Ask about operator training, the rigs they use (a rig that anchors firmly or vacuum-mounts correctly, with the right bit for the aggregate and reinforcement), and what insurance cover they carry. Ask to see the documents rather than relying on a verbal answer.

5. Can they work to your head contractor’s rules?

Commercial sites often add their own requirements on top of legislation. One national property group’s minimum requirements, for example, set a compulsory hold point where services and post-tensioned or prestressed cables must be located, verified and physically marked before penetration. Permits are required for work within 3 m of a known electrical, gas, water or telecommunications service, or where penetration depth exceeds 40 mm. A builder’s safety standard classifies coring and cutting as high-risk and requires a permit for penetrations of 50 mm or more into existing slabs, with the contractor’s SWMS submitted 7 days before work starts.

The thresholds differ from site to site, so ask the principal contractor or building manager for their rules before you book. A contractor used to these processes will not be surprised by them.

How a core hole is planned and drilled

A well-run job follows a repeatable sequence. Knowing it helps you judge whether a quote and a schedule are realistic.

1. Gather information. Structural drawings, the purpose of each hole, the diameter and the depth. If the building has post-tensioned slabs, say so at the start.
2. Define each hole. Set the position, size and whether it passes through a slab, a wall or a beam. Penetrations through beams, columns and other structural elements usually need engineering approval.
3. Scan. Map the area around each position and mark reinforcement, conduits, pipes and voids on the surface. Move a hole if the scan shows a conflict.
4. Permit and SWMS. Complete the safety plan and any site permits. Check the area below and behind the hole as well, so nothing is hit on the other side.
5. Set up and protect. Establish exclusion zones, secure the rig, and set up water control or extraction. Cover or protect finishes.
6. Drill. Drill with water to cool the bit and suppress dust, at the speed the bit and reinforcement call for.
7. Remove the core and clean up. Collect slurry, clean the area and check the hole for size and condition.
8. Close out. Confirm the holes against the plan and pass them to the next trade, with any sleeving, sealing or fire-stopping done by the responsible trade.

Our article on concrete drilling in tight spaces covers how this changes in plant rooms, ceilings and other restricted areas.

Core drilling near slab edges

Drilling close to a slab edge is one of the most common questions we hear, and it is a good example of why a blanket rule does not work. An edge can spall or crack when a hole is placed too close, and edges often carry concentrated reinforcement, edge beams, balcony ties or cast-in services. The right clearance depends on the hole diameter, the slab thickness, the reinforcement layout and what the slab supports.

What a careful contractor checks before drilling near an edge:

• Hole diameter against distance. Larger holes need more clearance. Ask how the proposed edge distance compares with the hole size, and whether the position can move inward.
• Reinforcement and cables. Scan the full footprint and the edge zone. Edges and slab ends are where post-tensioning anchorages and heavy reinforcement tend to concentrate.
• Slab type and load path. Balconies, cantilevers, transfer slabs and edge beams carry load differently from an internal slab. A penetration through them is a structural decision.
• Drill access and support. Rigs need a stable mounting. Near an edge, the crew may need a different anchoring method or support to keep the bit true.
• What is below. Check the space under the slab edge for people, services and facade elements, and exclude the area.

There is no single distance we would quote that is safe for every slab. If the hole is near a balcony, a basement wall, a transfer structure or any element you are unsure about, get written confirmation from the structural engineer before drilling. Send the drawings and the proposed locations to your contractor early so they can flag conflicts while moving a hole is still easy.

Safety rules that apply in Victoria

Concrete core drilling in Australia falls under the Work Health and Safety framework. SafeWork NSW’s code of practice explains that construction hazards, including silica dust and structural risks, must be managed, and typically a site-specific SWMS is needed for high-risk construction work. In Victoria, WorkSafe Victoria’s industry standard is the practical reference for cutting and drilling, and it covers SWMS, dust control, slurry and work near services.

In plain terms, you should expect a contractor to:

• Provide an SWMS that fits your site before work starts.
• Locate and verify services and structural elements before penetrating.
• Use water or extraction to control silica dust, and manage slurry.
• Set exclusion zones and use the right PPE and respiratory protection.
• Work within any permit system your site operates.

If your job involves manholes, pits or confined entries, there are further rules. Read our guide to manhole core drilling and why no entry is allowed without a permit before booking that kind of work.

What affects cost and timing

Core drilling quotes vary because the work varies. We price jobs to the site rather than publishing a per-hole rate, and these are the factors that move a quote:

• Number of holes. Setup, protection and clean-up are fixed effort, so one hole costs more per hole than twenty in the same area.
• Diameter and depth. Larger and deeper holes take longer, wear more bit and need more water and handling for the core.
• Concrete and reinforcement. Dense reinforcement or hard aggregate slows drilling.
• Access. Upper floors, basements, plant rooms, ceilings and tight spaces add setup time and may need specialist rigs.
• Scanning. A scan before drilling adds a task but removes the risk of striking a hidden service. Bundle it with the job.
• Permits and paperwork. Sites that require permits, inductions or SWMS lodgement days ahead need lead time built into the schedule.
• Out-of-hours work. Occupied buildings often require night or weekend work to limit noise and disruption.
• Cleanup and making good. Containing slurry and protecting finishes takes time, particularly indoors.

On timing, a small residential job can often be done in a single visit, while commercial work may need to follow your head contractor’s permit and program. Give your contractor the drawings, access details and hole schedule early so you can get a realistic quote and a firm date. For a quote on your project, you can request one from us directly.

How the job differs by project type

Residential clients tend to need clear communication about mess, noise and timing. Commercial clients need documentation and coordination with other trades. Industrial clients need capacity: larger rigs, deeper holes and short shutdown windows. If your job combines drilling with openings or removal, ask for a single scope that includes wall sawing or concrete removal so one crew can sequence the work.

Our perspective on hiring a core drilling contractor

We have worked on small domestic jobs and large commercial construction projects across Melbourne and Victoria, and the pattern is consistent: the jobs that go well are the ones planned before the rig arrives.

Our approach is built on licensed and qualified operators, advanced equipment and strict adherence to OH&S standards. We scan first, agree each hole’s purpose, diameter and position with you, and work to a safety plan that fits your site. That is how we aim to give you a safe, clean outcome without surprises.

Because we also offer scanning, wall sawing, wire sawing, rock drilling and concrete removal, we can recommend the right method for the job rather than adapting the job to one tool. If a hole is near a slab edge or a structural element, we will tell you what we need from your engineer before we start.

Send us your drawings and hole schedule, and we will tell you what the job involves and how we would run it.

MYBMC

Get a quote from Vic Sawing & Drilling

We provide core drilling, concrete scanning and related cutting services for commercial, industrial and residential projects across Melbourne and Victoria. Tell us the number of holes, the diameter, the slab type and the access, and we will plan the scan, safety documents and drilling around your site.

See our core drilling service or contact us through our main site for a free quote.

FAQ

Do I need a scan before core drilling?

Yes, for almost any hole in structural concrete. A scan maps reinforcement, conduits, pipes and post-tensioned cables so the hole can be positioned away from them. Many commercial sites make verified and marked locations a condition of work before penetration.

Is a SWMS required for core drilling in Victoria?

WorkSafe Victoria’s industry standard says an SWMS must be prepared before high-risk construction work, including work on or near electrical installations or services. Your contractor should supply one specific to your site, and your head contractor may want it submitted days before work starts.

How close to a slab edge can you core drill?

It depends on the hole diameter, slab thickness, reinforcement and what the slab supports, so there is no single safe distance. Scan the edge zone and have a structural engineer confirm positions near balconies, cantilevers, edge beams and basement walls before drilling.

What should a core drilling quote include?

A useful quote lists the number, diameter and depth of holes, scanning, access assumptions, working hours, slurry and dust control, and the safety documents provided. Sending drawings and photos with your enquiry makes the quote more accurate.

Can the same contractor do the cutting and removal around the holes?

Often yes. A contractor that offers wall sawing, wire sawing and concrete removal as well as core drilling can plan these tasks as one scope, which reduces handovers and site visits.

Sources

• SafeWork NSW: Working safely when cutting, drilling and grinding concrete
• WorkSafe Victoria: Safe concrete cutting and drilling industry standard
• Mirvac: Coring, boring and concrete cutting minimum requirements
• Baseline Projects: Penetration, coring and concrete cutting standard

Recommended

• Core Drilling - Concrete Core Drilling Melbourne
• Concrete Drilling Melbourne: Top Rated Concrete Drilling Company
• Clean Concrete Cuts with Precision Core Drilling
• Core Drilling Basics: A Beginner’s Guide

Foundation rock drilling is the work of boring holes into rock so a structure can be founded on it: investigation boreholes that show what the ground is, then drilled shafts, piles, anchors or micropiles that carry load into competent rock. Getting it right depends on three things: knowing the ground before you drill, matching the method to that ground, and running the site safely. This guide covers all three for Australian projects, and shows where a concrete and rock drilling contractor like us fits in.

TL;DR

• Foundation rock drilling covers two jobs: investigating the ground with boreholes, and forming the foundation itself, for example a rock-socketed pile.
• Method follows geology, hole depth and diameter, then access and environmental limits. Rigs differ widely: Kelly drilling is used to roughly 125 m and continuous flight auger to about 50 m.
• Money spent on rock coring early can save far more later. One Australian case study cut piling cost from $620,000 to $425,000 after about $5,000 of extra bedrock coring.
• Before any drilling starts, check for buried services, prepare a safe work method statement where the work involves deep shafts, and use qualified, licensed operators.
• We drill rock and concrete across Melbourne and Victoria. Tell us the scope and we will tell you plainly whether it suits our equipment.

Table of Contents

• What foundation rock drilling actually covers
• When a foundation needs to go into rock
• How a rock-socketed pile is built
• Drilling methods and rigs used in foundation work
• How engineers choose the method
• Plan around the ground, not the other way round
• Time and cost: why investigation money pays back
• Safety and site rules that apply
• Our perspective
• Where Vic Sawing & Drilling fits
• A pre-brief checklist for your drilling contractor
• FAQ
• Sources

What foundation rock drilling actually covers

The phrase is used for two different activities, and mixing them up leads to bad briefs and bad quotes.

Investigation drilling. Before major construction, boreholes explore the soil, rock and groundwater to judge whether the ground can safely support the structure, as Douglas Partners explains in its guidance on borehole data. The logs replace assumptions with evidence: soil type, rock quality, groundwater and fractured zones. Engineers then select and detail the foundation from that record.

Foundation construction drilling. Once the design is set, holes are drilled to form the foundation: bored piles socketed into rock, micropiles, rock anchors, dowel holes and shafts. This is where drilling diameter, verticality and cleanliness of the hole matter most.

In Melbourne, basalt and Silurian mudstone and siltstone are the rock types you will hear about most often, and their strength and weathering vary from one end of a site to the other. That variability is the reason drilling evidence matters more than a desktop assumption.

When a foundation needs to go into rock

Shallow footings and slabs work where the near-surface soil is strong enough. Rock becomes the target when:

• the soil above is soft, fill, or highly reactive and would settle or move;
• loads are concentrated, such as columns in a multi-storey building, bridge piers or heavy plant;
• the site is sloping or retained, and the foundation needs to resist lateral and uplift loads;
• groundwater or poor soil makes shallow excavation impractical.

An Australian piling paper published through OneMine notes that large-diameter rock-socketed piles can be an economical and environmentally acceptable way to carry very large concentrated loads, where the geology suits and the right equipment and techniques are available. That last condition is the one that decides most real projects.

How a rock-socketed pile is built

The Australian Geomechanics Society’s paper on rock-socketed piles in Sydney sandstone describes the sequence that applies, with local variations, to most rock-founded piles:

1. Bore through the soil with a rotary rig, into the competent founding rock.
2. Support the hole with temporary casing or drilling fluid where the soil would otherwise collapse.
3. Drill the rock socket, which is often roughened so the concrete grips the rock better.
4. Clean the base of the hole so no loose debris sits under the pile.
5. Lower the reinforcement cage into the shaft.
6. Place concrete through a tremie pipe, with geotechnical supervision checking the rock encountered and the final socket.

The same society’s guidance on construction performance adds the quality points that separate a good pile from a problem one: appropriate drilling tools, proof-core drilling, the available site investigation information, and full-time geotechnical supervision. Shafts should be kept substantially free of smeared or crushed rock, and pile bases free of debris. Smear is what you get from the wrong tool or a worn bit, and it reduces the bond between concrete and rock.

Drilling methods and rigs used in foundation work

Equipment manufacturer BAUER lists the common drilling methods in foundation engineering as Kelly drilling (up to 125 m deep), continuous flight auger (CFA) drilling (up to 50 m deep) and full displacement piling. The same page notes that cased CFA is increasingly used for secant pile walls because of shorter installation times and better vertical precision than traditional Kelly drilling.

In practical terms:

The big piling rigs are specialist machines operated by piling contractors. The smaller end of rock drilling is different: anchor holes, dowels, probe holes, coring through slabs into rock below, and drilling in places where a tall rig will not fit. That is where we work. If you want to understand how drilling approaches differ in more detail, our guide to rock drilling methods walks through rotation speed, flushing and a pre-job checklist.

How engineers choose the method

According to The Driller, method choice should ideally be guided by geology, hole depth and diameter, with hole linearity, drill access and environmental restraints also playing a part. The same article makes an honest observation: ground conditions dictate the technical method, but historical bias and regional experience often strongly influence which method a contractor proposes. The sensible response is to specify performance (diameter, verticality, socket roughness, base cleanliness, sample recovery) and let tenderers show how they will meet it.

A useful set of questions to put to any drilling contractor:

• What rock strength and weathering does the investigation show, and does your equipment suit it?
• What is the required hole diameter, depth and tolerance on verticality?
• Can the rig physically reach the location, and what ground bearing does it need?
• How will cuttings, slurry and water be handled and contained?
• Who confirms the rock has been reached, and who signs off the base?

Plan around the ground, not the other way round

The Queensland Department of Transport and Main Roads (TMR) has published a Geotechnical Investigations Guideline that is written for road projects but sets out a planning approach any foundation job can borrow. Planning starts with a desktop study and a gap analysis, then considers the project phase, site access, design elements, ground conditions, environmental and cultural heritage constraints, and health and safety risks. The aim is to cut the chance of unexpected latent conditions during construction.

For a Victorian project, apply the same order:

1. Desktop study. Collect geological maps, previous borehole logs for neighbouring sites and any services records.
2. Gap analysis. Identify what the desktop data cannot tell you, usually rock level and quality at the actual footprint.
3. Targeted boreholes. Place them where loads will be concentrated, not just where access is easy.
4. Design and method selection. Let the engineer set socket lengths and tolerances from the logs.
5. Access and logistics. Check overhead clearance, ground bearing, laydown space, and where water and spoil will go.
6. Construction supervision. Confirm the rock actually met matches the design assumption.

TMR’s guideline also says that for its investigations, work must comply with AS 1726 (the Australian geotechnical site investigations standard), and that drilling must be done by a suitably qualified and licensed contractor in line with the Queensland Water Regulation 2016. Those are Queensland requirements for TMR work. In Victoria, check what your client, council or the relevant authority requires for bores, groundwater and licensing before you engage a driller.

Time and cost: why investigation money pays back

There is no standard price per metre that holds across sites, because rock strength, access, hole size and depth change everything. What the evidence does show is the cost of under-investigating. A Douglas Partners paper, Saving on the Geotechnical Investigation: A False Economy, reports one Australian project where additional bedrock coring costing about $5,000 supported a redesign that cut piling cost from $620,000 to $425,000 and piling duration from 47 days to 19 days. Those figures are specific to that project and are not a benchmark, but the mechanism is general: better information avoids conservative pile dimensions, excess concrete and reinforcement, extra spoil and extra time.

Factors that move the cost and programme on a real job:

• Rock strength and abrasiveness, which control penetration rate and bit wear.
• Hole diameter and depth, since volume of rock removed rises quickly with diameter.
• Ground above the rock, including fill, boulders, groundwater and the need for casing.
• Access, such as tight basements, low headroom, or sloping sites.
• Spoil and water management, including slurry removal and disposal.
• Testing and supervision, such as proof coring and geotechnical inspection.
• Mobilisation, because several small holes cost far more per hole than a continuous run.

On our side, the published range for concrete cutting is $450 to $5,000 per job, depending on the scope. Rock drilling is quoted per project because the variables above differ every time, so send us the details rather than expecting a rate card.

Safety and site rules that apply

Drilling for foundations puts people near rotating machinery, deep openings, buried services and often wet, muddy ground. Four checks matter before the rig arrives.

Locate buried services. Safe Work Australia’s excavation guidance says to contact Before You Dig Australia before work starts, to check where electrical cables and other assets sit. Where drilling goes through or beside an existing slab, concrete scanning for reinforcement and conduits is the next step. Our checklist on concrete scanning before drilling covers what crews should confirm.

Prepare a SWMS. The Model Code of Practice for Excavation Work states that a safe work method statement must be prepared for construction work in or near a shaft or trench deeper than 1.5 metres, or a tunnel. It also says risk assessments should consider local conditions such as ground slope, adjacent buildings, groundwater and structural fractures in the rock mass. Deep foundation shafts fall squarely into this.

Check the machine every shift. A drill rig or support plant with a worn hose, loose guard or failed brake is a hazard before it turns a bit. A structured machinery pre-start checklist gives operators and supervisors a consistent record to work from.

Control the hazards of the drilling itself. Dust, noise, slurry, vibration and strikes on reinforcement are the usual ones, and we have covered them in the hazards of drilling into concrete.

TMR’s guideline adds that investigation planning should consider environmental and cultural heritage risks or constraints. On Victorian sites, that means checking heritage overlays and Aboriginal cultural heritage requirements before ground is disturbed, not after.

Our perspective

We are a concrete cutting and drilling contractor, and most of our rock work sits inside concrete projects: openings, anchor and dowel holes, coring through slabs into the rock below, and industrial drilling where access is limited. In our experience the jobs that go well share three things. The ground is understood before anyone mobilises, the hole specification is written down, and the person drilling knows what is behind and under the surface.

That last point is why we scan first. A hole that hits reinforcement or a live conduit costs more than the scan would have. We also prefer to say early when a job needs a large piling rig rather than our equipment, because a mismatched method wastes your programme and ours. When the scope suits us, you get licensed and qualified operators, equipment chosen for the rock, and work run to OH&S standards from small domestic tasks to large construction sites.

— MYBMC

Where Vic Sawing & Drilling fits

If your project needs rock drilled for anchors, dowels, probe holes, coring or industrial work in Melbourne or elsewhere in Victoria, see our rock drilling service. Where the hole passes through concrete first, our core drilling and concrete drilling services cover the slab section, and we scan before we cut. Send us the location, hole size, depth and any investigation logs, and we will give you a free quote or tell you honestly if another trade is the better fit.

For how we approach larger sites, read our best practices for commercial concrete drilling.

A pre-brief checklist for your drilling contractor

Before you request quotes, gather:

• the geotechnical report or borehole logs, and the design drawings showing hole positions;
• required diameters, depths, socket lengths and tolerances;
• site access details: gate width, overhead clearances, ground bearing, level changes;
• known services, and the result of your Before You Dig enquiry;
• water, slurry and spoil arrangements;
• the programme window and any noise or work-hour limits from council or the building owner;
• who will supervise and sign off the rock and the hole base.

A contractor who receives all of that can price accurately and flag problems early. One who receives a one-line email will price the risk instead.

FAQ

What is the difference between rock drilling and core drilling for foundations?

Rock drilling is the broad term for making holes in rock, using rotary, percussive or rotary-percussive methods. Core drilling uses a hollow diamond bit that cuts a cylinder and returns it as a sample, which is why it is used for proof coring and for clean, accurate holes through concrete and rock. Many foundation jobs use both.

How deep can foundation drilling go?

It depends on the rig. BAUER states that Kelly drilling reaches up to 125 m and CFA drilling up to 50 m. Most building foundations are far shallower, and depth is set by where competent rock is found and what the engineer specifies.

Do I need a geotechnical investigation before drilling piles?

In practice, yes. Borehole logs show soil, rock quality, groundwater and fractured zones, and engineers use them to size the foundation. The Douglas Partners case study shows how a small extra spend on coring can prevent over-designed piles. Your engineer and the relevant authority will confirm what is required on your site.

What safety paperwork does deep foundation drilling need?

Safe Work Australia’s excavation code says a safe work method statement is required for construction work in or near a shaft or trench deeper than 1.5 metres. You should also contact Before You Dig Australia before work starts. Confirm any extra obligations with your principal contractor and WorkSafe Victoria.

Can you drill rock on a tight or occupied site?

Often yes, using smaller rigs or handheld and rig-mounted core equipment instead of a large piling machine. Access, dust, noise and water control decide what is practical. Send us the site details and we will say what we can do.

Sources

• How to interpret borehole data for foundation design? (Douglas Partners)
• Saving on the Geotechnical Investigation: A False Economy (Douglas Partners)
• Large Diameter Machine Bored Piles in Australia (OneMine)
• Construction of rock socketed piles in Sydney sandstone (Australian Geomechanics)
• Construction of rock socketed piles to meet performance requirements (Australian Geomechanics Society)
• Drilling methods (BAUER Maschinen)
• The Basics of Geotechnical Construction Drilling, Part 1 (The Driller)
• Geotechnical Investigations Guideline (Transport and Main Roads, Queensland)
• Model Code of Practice: Excavation work (Safe Work Australia)
• Excavation (Safe Work Australia)

A stair opening in an existing concrete slab is cut with diamond wall saws, wire saws or ring saws, but only after an engineer has confirmed the slab can lose that section, the slab has been scanned for steel and services, and any required approvals are in place. The sawing itself is often the shortest part of the job. The planning, support and safe removal of the cut panels decide whether it goes well. This guide walks through the sequence we follow in Melbourne and across Victoria, so you know what to ask for and what to expect.

TL;DR

• Never cut first. An engineer must assess the slab type, span, supports and the opening’s position before any saw touches the concrete.
• Scan the slab for reinforcement, post-tensioning tendons, conduits and pipes. Drawings are a starting point, not proof of what is inside.
• Check the permit pathway with your building surveyor, because approvals for work on existing buildings vary by state and territory.
• Cutting a stairwell void is high-risk work in Victoria: expect a Safe Work Method Statement, wet cutting, exclusion zones and a controlled plan for lifting out the cut panels.
• Cost depends on slab type, opening size, reinforcement, access, temporary support and how the panels leave the building.

Table of Contents

• What a stair opening in a slab actually involves
• Step 1: Find out what the slab really is
• Step 2: Scan before you mark
• Step 3: Engineering, approvals and the Australian rules
• Step 4: Temporary support and strengthening
• Post-tensioned slabs: a separate process
• Step 5: How the void is cut and the panels are removed
• Safety controls that apply on the day
• What affects the cost and the time
• Our perspective: plan the void as an engineering task
• Get your stair opening cut by a crew that scans first
• Frequently asked questions
• Sources

What a stair opening in a slab actually involves

When a building gains a new staircase between levels, a section of the suspended slab has to go. That sounds simple, but a floor slab is part of the structure. It carries loads sideways to beams, columns and walls. Taking out a rectangle of it changes how those loads travel.

The STRUCTURE magazine article on openings in existing floors sets out the normal sequence. You choose the location after reviewing available construction documents and inspecting and probing the floor. You assess the structural effects, obtain a construction permit where required, install shoring for interim loads, mark the corners to prevent overcutting, and then saw with diamond blades. Strengthening may be needed around the new edge.

The same article explains why this matters. An opening can remove reinforcement, reduce stiffness or flexural resistance, overload neighbouring areas, or disrupt the original load path. That is why the order of work is fixed, and why we do not start cutting on a verbal “it should be fine”.

Step 1: Find out what the slab really is

Before anything is marked on the floor, someone has to establish the slab type, its span and its support conditions. The position of the opening relative to columns and beams matters as well, because guidance on cutting stair or riser openings points to these as the first questions for the engineer.

Common slab types behave differently:

• One-way slabs span in a single direction. The direction of your opening decides which reinforcement is interrupted.
• Two-way and flat slabs carry load in both directions. Openings near columns raise punching-shear concerns, so the engineer will look hard at any void close to a column.
• Post-tensioned slabs hold high-tension steel tendons. They need their own process, which we cover below.
• Composite metal deck slabs use the deck profile as tension reinforcement, which changes the strengthening approach.

Start with the paperwork. The Australian Building Codes Board handbook on upgrading existing buildings tells you to locate documentation about the original design, approval and construction first. It also warns that existing construction should not be assumed to match those documents. Older Melbourne buildings have often been altered, and the as-built slab can differ from the drawings.

Step 2: Scan before you mark

Scanning turns an assumption into a map. Ground-penetrating radar and similar methods can identify reinforcing steel, post-tensioning tendons, electrical conduits and pipes that may not appear on structural drawings. That matters for two reasons: you do not want to hit a live conduit, and the engineer needs to know which bars the cut will interrupt.

WorkSafe Victoria’s industry standard goes further. Its Safe concrete cutting and drilling standard says planning must confirm the structural components and services in the slab, include structural-engineer advice for alterations, and use a competent person to supervise the work.

Our concrete scanning service covers this stage. If you want to understand the technology first, we explain what concrete scanning is, compare five scanning methods and list seven checks before drilling that apply equally to saw cuts.

What the scan results change

The scan can move the opening by a few hundred millimetres, or change the cutting sequence. Typical outcomes include:

1. A clash with a pipe or conduit that must be isolated or relocated before cutting.
2. A concentration of reinforcement along one edge, which affects how the engineer designs trimmer beams or plates.
3. Tendons in a slab that was thought to be conventionally reinforced, which stops the job until the post-tensioned process has been followed.

Mark the confirmed outline on the slab and mark the corners clearly. The STRUCTURE article notes that marking corners helps prevent overcutting, where the blade runs past the corner into slab that must stay.

Step 3: Engineering, approvals and the Australian rules

An engineer, not the cutting contractor, decides whether the opening can be made and what must be added. Their analysis should evaluate load paths, punching-shear capacity near columns and the reinforcement being interrupted, particularly in two-way flat slabs or post-tensioned construction. They will also consider the cumulative effect of other penetrations. Several small penetrations close together can have a significant combined effect on slab strength and stiffness, so tell the engineer about any core holes and service risers nearby.

Permits and the National Construction Code

The NCC does not generally apply to existing buildings unless they are altered, extended or change use, and it gets legal effect through state and territory frameworks. Adding a stair void is an alteration. The ABCB handbook adds that application and approval processes for upgrading existing buildings vary by state and territory, and recommends advice from an appropriately qualified person where assessment and analysis are needed.

In practice, confirm with your building surveyor whether the work needs a building permit before you book a crew. We do not issue permits and we do not replace your engineer, but we will work to the engineer’s drawings and sequence.

The stair itself must comply

The opening is only useful if the stair that goes in it is compliant. For housing, the NCC 2022 provisions on stairway construction cover limits on risers per flight, consistent risers and goings, the 2R + G relationship, and restrictions on openings in risers. Give your designer or stair builder the exact void size before the cut, because a void that is 100 mm short can force an awkward stair layout that cannot be fixed afterwards. Commercial buildings follow different parts of the code, so ask your designer which provisions apply.

If the new stair also leads to a landing, handrail or balustrade in an older home, plan that early too. In heritage houses, balustrade restoration for heritage homeowners is worth considering alongside the new void edge so the finished staircase suits the original character.

Step 4: Temporary support and strengthening

The slab does not stop carrying load the moment a saw cuts through it. The STRUCTURE article explains that temporary shoring can support interim design loads, and that it may be omitted if the floor is strengthened before the opening is made. After the opening exists, permanent strengthening can include transfer beams or externally bonded or bolted steel plates.

The engineer specifies which approach applies. Typical practical questions are:

• Does the floor below need propping, and who is responsible for installing and removing the props?
• Is the strengthening installed before or after the cut?
• Can the area below stay occupied, or must it be cleared?

In Victoria, structural alterations involving temporary support to prevent collapse count as high-risk construction work under the Occupational Health and Safety Regulations 2017, so a Safe Work Method Statement (SWMS) is required.

Post-tensioned slabs: a separate process

Post-tensioned slabs are common in Melbourne apartment and commercial buildings. Cutting one without a plan can release stored energy in the tendons. The Concrete Repair Institute’s technical article says large stairwell openings in post-tensioned slabs need engineering analysis, that existing tendons must be located, and that affected strands may need to be detensioned and reanchored before concrete removal. That article is from the United States, so follow Australian standards and your engineer’s design for the actual job.

Our article on three checks engineers require before cutting post-tensioned slabs goes through this in more detail. If the scan finds tendons, stop and tell your engineer before any cutting.

Step 5: How the void is cut and the panels are removed

For a stairwell void, the main methods are wall sawing and wire sawing. WorkSafe Victoria’s standard says a stairwell opening can be cut by wall sawing or wire sawing, and that you need a controlled method for removing the concrete blocks, securing them against overturning or falling, and confirming that any crane or lifting device is designed for the load.

Corner core holes are a common technique. They give a clean radius or stop point, so straight saw cuts do not extend past the corner and weaken the slab. Core holes can also take lifting anchors for the cut panels.

Managing the cut panels

A 150 mm thick slab weighs a lot per square metre, so a stair void cut into sections produces heavy panels. Before cutting, decide:

1. How big each panel can be given the lifting equipment and the route out.
2. How each panel is secured before the final cut so it cannot drop onto the floor below.
3. Whether panels go out by crane, by hoist or are broken down in a controlled way. Our concrete removal service can handle breakdown and disposal when the job needs it.

This is also why access matters. A void in a basement carpark and a void in a fifth-floor apartment need different removal plans even when the slab is the same thickness.

Safety controls that apply on the day

WorkSafe Victoria’s standard calls for a qualified person to determine slab capacity when sawing suspended slabs, control unneeded services, secure the cut area and set up an exclusion zone. Combined with the wider standard, the controls on a typical stair void job include:

• SWMS prepared for high-risk work, including tasks with a risk of falling more than 2 metres, which applies when the void opens onto a lower level.
• Wet cutting and respiratory protection to control dust. Our guides on wet versus dry cutting and minimising dust when sawing concrete cover the methods, and our page on dustless concrete cutting explains capture at source.
• Exclusion zones and barricades above and below the cut.
• Service isolation and electrical controls, including water near powered equipment.
• Manual handling and vibration controls for operators.

Silica is the reason dust control is not optional. The exposure standard for respirable crystalline silica is 0.05 mg/m3 as an 8-hour time-weighted average, and WorkSafe Victoria recommends keeping exposure below 0.02 mg/m3. WorkSafe also lists manual handling, vibration and loss of vacuum pressure in suction-held equipment among the key hazards in concrete cutting. For a wider look at site practice, see our summary of safety measures for concrete cutting.

What affects the cost and the time

Nobody can quote a stair void accurately from a photo. Time and cost depend on the same factors that shape the engineering:

• Slab type and thickness, including the reinforcement or tendons the cut interrupts.
• Opening size and position, which sets the length of cut and the panel sizes.
• Strengthening and temporary support, which can be a bigger line item than the sawing.
• Access and occupancy, including working in occupied buildings, after-hours work and lift or stair limitations.
• Panel weight and removal route, which decide whether you need a crane, hoist or breakdown on site.

These factors are consistent with published guidance on slab openings. For reference, our published price range for concrete cutting jobs is $450 to $5,000 one-off, and a stair void will sit wherever your slab, access and engineering put it. Scanning, engineering fees, shoring and stair fabrication are separate from the cutting. Ask for a written scope that lists what is and is not included.

Our perspective: plan the void as an engineering task

Most problems we see on stair openings come from skipping steps, not from the cutting. A plan sketched on a floor plan looks tidy, then the scan shows a bundle of conduits exactly where the stair should start. Or an owner books a crew before the surveyor has confirmed the permit pathway. Neither is a cutting failure, but both stop a job halfway.

Our view is simple. Treat the opening as a structural alteration from the first phone call. Get the engineer involved early, scan the slab before the design is fixed, and ask your cutting contractor to work to the engineer’s sequence. Licensed and qualified operators, suitable equipment and strict OH&S practice are what we bring to that sequence. The same discipline applies whether it is a small domestic stair in a renovation or a large commercial project across several levels.

If you are unsure about a detail, ask us before you commit to a design. A short conversation about access, panel size and cutting method can save a redesign.

— MYBMC

Get your stair opening cut by a crew that scans first

We provide concrete scanning, wall sawing, wire sawing, ring sawing, core drilling and concrete removal across Melbourne and Victoria, for contractors, property managers, architects, engineers and homeowners. Send us your engineer’s drawings and site access details through our main page and we will quote the cutting, scanning and removal as one scope. For larger jobs, see concrete cutting around Melbourne.

Frequently asked questions

Can I cut a stair opening in a concrete slab without an engineer?

No. WorkSafe Victoria’s industry standard calls for structural-engineer advice for alterations to slabs and a competent person to supervise. The engineer checks load paths, supports and reinforcement, and specifies any strengthening. Cutting without that advice risks damaging the structure and the people below.

Do I need a permit to cut a stairwell void?

Often yes, because adding a stair is an alteration to an existing building. Approval processes vary by state and territory, so ask your building surveyor before work starts. Your surveyor will tell you which documents, such as engineer’s drawings, they need.

What is the best way to cut a stairwell opening?

Wall sawing and wire sawing are the methods WorkSafe Victoria names for stairwell openings. Wall sawing suits straight, accessible cuts, while wire sawing handles thick or awkward slabs. Corner core holes and hand sawing finish the corners without overcutting.

Can a post-tensioned slab have a stair opening?

Sometimes, but only with engineering analysis. Tendons must be located by scanning, and affected strands may need to be detensioned and reanchored before the concrete is removed. Never cut a slab you suspect is post-tensioned until the engineer has signed off the plan.

How long does a stair opening take to cut?

The cutting can take a day or less for a standard residential void, but scanning, engineering, approvals, propping and panel removal add time before and after. Slab thickness, reinforcement, access and the removal route set the timeline. We confirm it once we have the drawings and have seen the site.

Sources

• Creating an Opening in Existing Floors, STRUCTURE magazine
• Cutting a New Stair or Riser Opening Through an Existing Slab
• Upgrading Existing Buildings handbook, ABCB
• Safe concrete cutting and drilling industry standard, WorkSafe Victoria
• Before Cutting a Concrete Slab: What Commercial Renovation Teams Should Know
• General NCC FAQ, ABCB
• Part 11.2 Stairway and ramp construction, NCC 2022
• Creating Openings in Unbonded Post-Tensioned Slabs, ICRI
• Crystalline silica: Safety basics, WorkSafe Victoria
• Safe concrete cutting and drilling industry standard page, WorkSafe Victoria
• Balustrade restoration for heritage homeowners

Recommended

• Concrete Cutting: Guide to Cutting A Door Into A Concrete Wall

Scupper drain coring is the process of cutting a round opening through a concrete parapet, upstand or slab edge so that rainwater can leave a flat roof, podium or balcony. It looks simple, but it is a structural penetration in a waterproofed element, and it is cut after the concrete has cured. That means reinforcement, conduits and membranes are already in the way. This guide explains how the work is planned and done in Victoria, what it depends on, and what to prepare before you ask for a quote.

TL;DR

• A scupper core is a structural and waterproofing detail, not just a hole. The size, level and position come from the roof drainage design, not from the drill.
• Scan before you cut. Concealed rebar, electrical conduit and post-tension cables are the main risk, and WorkSafe Victoria’s industry standard expects the work to be planned around them.
• Wet coring with a properly fed rig controls silica dust and clears slurry. Slurry also has to be contained so it does not run onto the façade or the level below.
• Give your contractor the drainage drawings, the core diameter, the invert level and the waterproofing details. Vague notes cost time on site.
• For scupper coring in Melbourne and across Victoria, Vic Sawing & Drilling provides core drilling with scanning and wet methods.

Table of Contents

• What a scupper is and why it gets cored
• Get the drainage design right before anyone drills
• Choose the core diameter and position
• Scanning: the step you cannot skip
• How the core is actually cut
• Water, slurry and silica
• Waterproofing and finishing the opening
• Planning the job: who needs what
• Why DIY and general trades often go wrong
• Our view: treat the scupper as a detail, not a hole
• Cutting and coring with Vic Sawing & Drilling
• FAQ
• Sources

What a scupper is and why it gets cored

A scupper is an opening in a parapet wall or roof edge that lets water discharge to a downpipe, rainhead or open drop. On flat roofs, podium decks and car park ramps, scuppers often act in two roles. Some are the primary outlet. Others are overflow openings that sit slightly higher and only work when the main drainage is blocked or overwhelmed.

In new concrete, designers sometimes cast a sleeve into the formwork. Coring comes in when:

• the sleeve was missed, misplaced or sized wrong;
• a renovation adds a roof outlet to an existing building;
• an overflow is added after a surveyor or engineer flags a compliance gap;
• a roof is re-levelled or re-waterproofed and the old outlet no longer lines up;
• a tenancy or plant upgrade changes where water needs to go.

The cut is usually a straight horizontal core through a parapet, sometimes a slight angle, and occasionally a vertical core through a slab edge or balcony upstand. Rectangular scuppers are also possible. These are made by overlapping cores or by wall sawing, where a wall saw cuts a clean rectangular opening to the marked lines.

Get the drainage design right before anyone drills

The core is only as good as the number it is based on. Roof drainage in Australia is designed to the National Construction Code and AS/NZS 3500.3. For Victoria, the NCC 2025 provisions in Part E3 on stormwater and roof drainage systems cover design, installation and maintenance of roof drainage. AS/NZS 3500.3:2018 sets the requirements for materials, design, installation and testing of roof drainage systems.

A few practical points follow from this:

1. Capacity is calculated, not guessed. The designer works out the rainfall intensity for the site and the catchment area feeding the outlet. A hydraulic designer or plumber should confirm how many scuppers are needed and how large they must be.
2. Overflow matters as much as the primary outlet. An overflow opening that is cored too high, or too small, will not do its job in a blockage. The Victorian Building Authority has published guidance on sizing a roof catchment drainage system, which is a good reference for the engineer or plumber on your project.
3. Level is critical. Water should run to the opening, not pool behind it. A core placed even 20 to 30 mm too high can leave a permanent puddle against the membrane.
4. Document it. The VBA has said that drainage details need to be clear enough at the permit stage for a building surveyor to check them against the NCC, so avoid notes like “scuppers as required”. If you need a refresher on keeping drainage records, this guide to plumbing as-built drawings explains what good documentation looks like.

If you want a quick feel for how slope and outlet position interact on a low-pitch roof, this explanation of flat roof drainage slope is a readable starting point. It comes from a US roofing context, so treat the numbers as illustrative and use the Australian standards and your designer’s figures for the actual job.

We do not size scuppers. That belongs to the hydraulic engineer, architect or licensed plumber. What we do is cut to the dimensions and levels they give us, and tell you early if the structure suggests a problem.

Choose the core diameter and position

Core diameter depends on the flow needed and on what the parapet can tolerate. A few rules of thumb that engineers commonly apply:

• Multiple smaller cores can behave differently from one large one. Debris can block small holes more easily. Your designer will decide whether a single large core, a row of cores or a rectangular opening is best.
• Edge distance and reinforcement count. The closer the opening is to a corner, a joint or a beam, the more likely it is to hit heavy steel or weaken the element. Large-diameter cores need more consideration, and our page on rig sizing and SWMS for large-diameter coring explains how rig choice changes with size.
• Thickness changes the method. Parapets are often thinner than slabs, which helps, but if the wall has a thick cap or a thickened base, the bit length and rig set-up change. For depth limits generally, see how deep you can core drill concrete.
• Fall for the water. Where the scupper discharges into a downpipe or rainhead, the core may be set with a slight fall toward the outside. Say so in the brief.

Mark the centre point and the invert level on the wall before the crew arrives, or arrange for the designer to attend. A centre mark on a plan is useful, but a physical mark on a clean surface prevents misunderstandings.

Scanning: the step you cannot skip

Before any bit touches concrete, the area needs to be scanned for reinforcement, conduits and services. The research for this guide is consistent with WorkSafe Victoria’s Safe concrete cutting and drilling industry standard, which covers core drilling and wall cutting and expects hazards such as concealed services to be identified and controlled before the work starts.

What scanning tells you on a parapet:

• where vertical and horizontal bars sit, and at what spacing;
• whether there are electrical conduits for roof lighting, sensors or aerials running through the upstand;
• how deep the cover is, so the crew knows what the core will meet;
• whether there is an unexpected void or a cast-in sleeve.

If the scan shows a bar right on the centre line, the options are to shift the opening, cut through the bar with the right bit and with the engineer’s approval, or change the opening shape. That is an engineering decision, not a site guess. Our guide to concrete scanning before drilling lists the checks we expect on Australian jobs.

A word on bits: not every diamond core bit is built for steel. Using the wrong bit on rebar loads the tool, builds heat and may fail to cut the bar, which creates a hazard and can damage the rig. A professional crew chooses the bit for the concrete mix, aggregate and the expected steel, not just for the diameter.

How the core is actually cut

Here is the sequence on a typical parapet scupper.

1. Site check and set-up. The crew confirms the marked centre, the invert level and the access. Power and water are connected, and a SWMS is in place.
2. Scan and re-mark. The area is scanned, results are marked on the surface, and any change to the position is agreed with the designer.
3. Isolate the area below. Cores can drop unexpectedly. The area below the drill site should be barricaded, or a spotter should be used, so nobody is under the opening when the core releases.
4. Fix the rig. The core drill is anchored to the wall or slab, usually with an anchor bolt or a vacuum base where the surface suits it, so it cannot wander off the marked centre. A rig that shifts will cut an oval, jam the bit or both.
5. Wet coring. Water is fed to the bit throughout. Slurry is captured with a collection ring or a wet vacuum, and diverted away from the roof membrane and façade.
6. Core extraction and support. In a horizontal core, the plug can fall outward or jam in the hole. The crew supports it, or breaks it into sections, before it drops.
7. Clean up and handover. The opening is cleaned, edges are checked, and the level and diameter are confirmed against the drawings, ready for the waterproofer and plumber.

If you want a wider view of the technique itself, our pages on what core drilling is and core drilling techniques for accurate drilling explain the equipment and the precision involved. For planning holes for pipes and stormwater generally, see drainage core drilling.

Water, slurry and silica

Coring concrete produces fine dust that contains respirable crystalline silica. The workplace exposure standard in Australia is 0.05 mg/m³ as an eight-hour time-weighted average. That is a legal limit for exposure, and it is why wet methods are the first control on a coring job.

A few things we see misunderstood:

• A garden hose or spray bottle is not wet coring. The rig needs a proper water feed to the bit, at the flow the manufacturer specifies, so that dust is suppressed at the point of cutting and slurry is flushed out of the hole. Without that, the bit overheats and jams.
• Water and tools must be matched. Safe Work Australia’s national guide for working with silica says to use only tools and machinery designed for use with water, and notes that water suppression and local exhaust ventilation may need to be combined.
• Slurry is a site hazard. On a roof, slurry can run across the deck, stain the façade or enter the stormwater system. It needs capture and disposal, and the drain being installed should be protected from it.
• Electrical safety. Water and power tools need residual current protection and tidy leads.

We cover the difference in more detail in our article on wet versus dry cutting in Australia, and on how dust capture at the source works when a site cannot tolerate water mess, such as occupied buildings.

Waterproofing and finishing the opening

A bare cored hole is not a finished scupper. The cut face of a concrete upstand is a path for water into the structure unless it is sealed and integrated with the roof membrane.

Typical steps after coring, carried out by the waterproofer and plumber:

• clean and prime the cut face as the membrane manufacturer requires;
• install a sleeve, spout or outlet fitting sized to the core;
• lap the membrane onto or into the outlet, following the system’s details;
• seal the annulus between sleeve and concrete;
• flood test the roof and inspect the outlet.

External waterproofing membranes are covered by AS 4654.2-2012, which sets requirements for design and installation of above-ground external membranes. Check which system your project uses and ask the waterproofer what tolerance they need for the core diameter and surface finish.

A practical tip: tell your waterproofer the core date. If coring happens after the membrane is laid, the membrane around the opening will need to be cut back and re-detailed, which is more expensive than coring first.

Planning the job: who needs what

The people involved have different jobs, and most delays come from a gap between them.

What to send with your enquiry

• the drawing showing scupper position, diameter and invert level;
• wall or slab thickness and the building age and construction type, if known;
• any structural notes about reinforcement or post-tensioning;
• access details: roof hatch, scaffold, ladder, crane or swing stage;
• availability of power and water on the roof;
• the waterproofing programme and who is on site before and after coring.

Why DIY and general trades often go wrong

Homeowners and project managers commonly underestimate scupper coring. The common failure points are:

• No scan. A hand-held rotary hammer or hire core drill is pushed into concrete without knowing what is inside. Cutting a conduit or a tendon is a serious safety event, and it is expensive to repair.
• Rig not anchored. The rig walks, the hole is oval, and the sleeve will not seat.
• Wrong bit. A bit that is not suited to steel burns out on the first bar.
• Dry or improvised wet cutting. The silica exposure limit is easy to exceed, and the bit jams.
• Falling core. Nobody checked below, and the plug drops onto a footpath or balcony.
• Wrong level. The scupper is cored an inch above the roof surface, and water ponds permanently.

This is why we work only for clients who hire a service for a defined job, such as contractors, property managers, architects, engineers, industrial facility managers and homeowners who want the work done by a professional. We are not the right fit for people who want to do it themselves.

Our view: treat the scupper as a detail, not a hole

We cut concrete across Melbourne and Victoria for commercial, industrial and residential projects, from small domestic jobs to large construction sites, and the scupper jobs that go smoothly share three habits.

First, the drawings reach us before the date is booked. When we see the diameter, invert level and wall thickness up front, we can plan the rig, the bit and the access, and flag problems with the designer while there is still time to change the position.

Second, scanning is treated as part of the job, not an optional extra. Reinforcement in parapets is often denser than people assume, especially at corners and joints, and the scan result is what lets us hold the position the designer wants or propose a sensible shift.

Third, the sequence with other trades is agreed. Coring after the membrane is down creates rework. Coring before the sleeve is ordered creates delays. A short call between us, the waterproofer and the plumber saves more time than any equipment can.

Our operators are licensed and qualified, we work to OH&S standards, and we use wet methods and slurry control by default on coring work. If a site is not suited to coring, we will say so and suggest the alternative, such as a wall-sawn rectangular opening.

— MYBMC

Cutting and coring with Vic Sawing & Drilling

We provide core drilling and concrete drilling for parapet scuppers, roof outlets and other drainage penetrations, with concrete scanning before cutting. Where the opening needs to be rectangular, wall sawing is an option, and if the job grows into removing a section of upstand or slab, our concrete removal service covers that.

Our site lists concrete cutting as a one-off service priced from $450 to $5,000, depending on the job. Scupper coring has no fixed published price, since diameter, thickness, access and reinforcement all affect the work. To get a figure for your roof, request a free quote with your drawings and access details.

FAQ

What is the difference between a scupper and a downpipe?

A scupper is an opening through a parapet or wall edge that lets roof water out. A downpipe is the vertical pipe that carries that water down, often fed by a scupper and a rainhead or box. Many flat roof designs use both, with the scupper discharging into a rainhead above the downpipe.

Can a scupper be cored into an existing parapet?

Yes, in most cases, provided a scan shows the position is clear of services and the structural engineer is comfortable with the penetration. The core is cut wet, the rig is anchored, and the waterproofer detailed the opening afterward. If reinforcement or a joint is in the way, the position or shape may change.

How do I know what size scupper I need?

The size comes from the roof drainage design, based on catchment area and rainfall intensity under the NCC and AS/NZS 3500.3. A hydraulic engineer, architect or licensed plumber should confirm it. A concrete cutter drills to the dimensions you give.

Is wet coring really necessary for a small scupper?

Yes. Wet methods are the primary way to control silica dust, and the exposure standard of 0.05 mg/m³ applies to small jobs as well as large ones. A proper water feed also keeps the bit cool and clears slurry, so the hole is cleaner and the core is less likely to jam.

Should the core be cut before or after the waterproofing?

Before, wherever the programme allows. Coring first means the membrane can be detailed around a clean opening and sleeve. If the core is cut after the membrane is laid, the membrane has to be cut back and repaired, which adds cost and a risk of leaks.

Sources

• NCC 2025, Victoria Part E3 Stormwater: Roof drainage systems
• AS/NZS 3500.3:2018, Standards Australia
• VBA Plumbing Practice Note RP 06: Sizing a roof catchment drainage system
• WorkSafe Victoria: Safe concrete cutting and drilling industry standard
• Safe Work Australia: Workplace exposure standard for respirable crystalline silica
• Safe Work Australia: National guide for working with silica
• AS 4654.2-2012, Waterproofing membranes for external above-ground use
• Flat roof drainage slope guide

Recommended

• Drainage Core Drilling: Planning Holes for Pipes and Stormwater