Roof penetration coring is the process of cutting clean round holes through a concrete roof slab so pipes, drains, conduits, exhausts or plant supports can pass through. On a concrete roof in Victoria, doing it properly means four things in order: scan the slab for hidden services and reinforcement, get the paperwork and dust controls in place, core with a wet or dust-captured diamond drill, then hand the hole to the waterproofer so it is flashed as part of a complete system. Skip any of the four and you risk a damaged cable, a safety breach or a leak that shows up months later.

This guide is for contractors, property managers, engineers and building owners who need to plan penetrations in an existing concrete roof or podium deck.

TL;DR

• Scan before you core. Post-tensioning cables, conduits and rebar can sit anywhere in a roof slab, and a scan is the cheapest insurance on the job.
• In Australia, penetration or coring work 50 mm deep or more is treated as high-risk construction work on many managed sites, with a permit, risk assessment and SWMS.
• Cutting concrete creates respirable crystalline silica. Use water suppression or on-tool extraction, and clear the area.
• The core is only half the job. The penetration needs purpose-made flashing and a waterproofing system that integrates with the roof membrane.
• Plan the hole count, sizes and positions with the roofer before the drill arrives.

Table of Contents

• What roof penetration coring involves
• Why the hole is the easy part
• Step 1: Scan the slab
• Step 2: Permits, risk assessment and SWMS
• Step 3: Control silica dust and slurry
• Step 4: Core the holes
• Step 5: Restore structure and flash the penetration
• Planning checklist for contractors and property managers
• Common mistakes on roof coring jobs
• Our perspective
• Cost and what affects it
• Book roof coring in Melbourne
• FAQ
• Sources

What roof penetration coring involves

A roof penetration is any object or opening that passes through the roof surface. On a concrete roof, the opening is usually made with a core drill: a rig fitted with a hollow, diamond-tipped bit that cuts a cylinder out of the slab. The result is a round, smooth-walled hole that can be sized to suit the service going through it.

Typical reasons to core a roof slab:

• Roof drains and overflow outlets
• Mechanical exhaust, kitchen exhaust and ventilation risers
• Plumbing vents and stack penetrations
• Electrical and data conduits feeding rooftop plant
• Refrigerant lines for air conditioning condensers
• Posts for guard rails, anchors and fall-arrest systems
• Solar array cable entries

Coring is preferred over breaking out a hole with a jackhammer because it is accurate, causes little vibration and leaves a neat edge. That matters on an occupied building, where noise and shock travel down through the structure. If you want a primer on the process itself, our page on what core drilling is covers the basics.

Why the hole is the easy part

The drilling itself takes minutes per hole in most slabs. What goes wrong on roofs is almost never the core. It is what happens before and after.

The National Construction Code requires a roof to prevent water getting into the building, and the weatherproofing provisions cover openings. Industry guidance reflected in the code’s performance requirements, along with NCC Part H2 on damp and weatherproofing, makes clear that every opening is a place where moisture can enter. Roof penetrations are widely regarded as one of the most common leak points on any roof, which is why designers try to reduce their number in the first place.

Two practical conclusions follow:

1. Fewer, better-placed holes. Group services together where you can, and use a structural platform rather than many individual fixings. Facilities guidance from Australian National University says roof-mounted equipment should sit on a structurally sound platform designed with a limited number of roof penetrations.
2. A coordinated sequence. The coring contractor and the roofer need to agree hole positions, diameters and timing before anyone starts.

Step 1: Scan the slab

Before a bit touches the roof, you need to know what is inside it. Concrete roof slabs commonly contain reinforcing bar, electrical conduit, drainage falls cast into the topping and, in some buildings, post-tensioned cables. Hitting a tensioned cable is dangerous and expensive. Hitting rebar will stall the bit and may weaken the slab if cut without engineering approval.

The ANU facilities standard is blunt on this point: it calls for service scans before starting work to avoid hitting hidden conduits, rebar or post-tensioning cables. Our concrete scanning service uses ground-penetrating methods to map what is inside the slab, so holes can be moved a few centimetres to clear a cable instead of being abandoned or, worse, drilled blind.

What a good scan result gives you:

• Marked positions of reinforcement and conduits on the slab surface
• An approximate slab thickness, so you know how deep the core must go
• A clear go or no-go for each proposed location
• A record you can hand to the engineer

If the scan shows a hole location conflicts with structural steel or tendons, the engineer decides what happens next. That decision is not one for the drilling crew to make on the day.

Step 2: Permits, risk assessment and SWMS

In Australia, the requirement depends on the site and the building owner’s rules, but a widely used standard is clear. According to Baseline’s published coring standard, any penetration, coring or cutting that goes 50 mm or deeper into a structure such as a slab or wall is high-risk construction work. That standard requires a permit, a project risk assessment and an approved Safe Work Method Statement, submitted to the site representative at least 7 days before work starts.

Most roof slabs are well over 50 mm thick, so assume this applies. Even where a particular building does not use that exact standard, major managed buildings, hospitals, universities and shopping centres have similar rules.

What this means for your programme:

• Allow at least a week between engaging a coring contractor and starting, longer on a managed site.
• Make sure the SWMS names the specific hazards of a roof: edges, falls, services below, dust and slurry.
• Confirm who is on site for the permit. On a tenanted building, that may be the facilities manager rather than the owner.

We prepare job-specific documentation and run to your site’s induction and permit system. If you are early in planning, tell us when you send the enquiry so we can build the lead time into the schedule.

Step 3: Control silica dust and slurry

Concrete contains crystalline silica. Drilling it releases respirable crystalline silica (RCS), a serious long-term health hazard. Safe Work Australia’s model code of practice on managing the risks of respirable crystalline silica lists using power tools or mechanical plant for drilling or cutting a crystalline silica substance as a process that needs risk management.

The hierarchy of control matters. The Safe Work Australia silica guidance lists isolating the hazard, for example designating areas for dust-generating tasks, and engineering controls that minimise dust exposure. For rooftop work specifically, Safe Work Australia’s guide to rooftop solar installation says respiratory protection is only acceptable where engineering controls such as on-tool extraction or water suppression are not reasonably practicable. Respirators are the last line, not the plan.

In practice on a roof:

• Wet coring keeps dust down at the bit. The trade-off is slurry, which must be contained, vacuumed and kept out of drains and off membranes.
• Dust capture systems pull dust at the source when water cannot be used, for example above sensitive equipment or in occupied floors below.
• Exclusion zones keep other trades and the public clear while work is under way.

We compare the two approaches in wet versus dry cutting and explain how extraction works in our guide to dustless concrete cutting in Melbourne.

On a roof, slurry control has a second purpose beyond health. Wet slurry running across a membrane or into a roof drain stains finishes, blocks outlets and can contaminate the surface that the waterproofer needs clean and dry for adhesion.

Step 4: Core the holes

With scanning done, permits approved and controls in place, the coring itself follows a routine sequence.

1. Mark out each hole from the scan, checking diameter against the service and flashing to be fitted. Allow clearance around the pipe for the flashing and any sleeve.
2. Fix the rig. On a roof the rig is usually anchored to the slab or held by vacuum base so it cannot walk. A stable rig gives a straight, true hole.
3. Select the bit. Diamond segments are matched to the aggregate and the amount of steel expected.
4. Start the core with light pressure and water supply on, then let the bit do the cutting.
5. Remove the core plug. On a roof, ensure the plug cannot fall through to the floor below once the cut is complete. Plugs are supported or secured, and the area below is cleared.
6. Clean the hole. Vacuum slurry, remove loose material and leave the edge ready for the next trade.

Core depth and time depend on slab thickness and reinforcement. If you want to understand limits, see how deep you can core drill concrete and how long core drilling takes. For most roof penetrations, the drilling is a fraction of the total time spent setting up and cleaning up.

Tight access and rooftop logistics

Roofs are rarely easy places to work. Water supply, power, hoisting equipment and access through hatches can all shape the job. Plant rooms and parapet edges limit where a rig can sit. Our notes on concrete drilling in tight spaces cover how we approach cramped locations. Tell us early about hatch sizes, lift access and whether a crane is available, because it changes the equipment we bring.

Step 5: Restore structure and flash the penetration

Once the core is out, two questions remain: is the structure still sound, and will the hole stay watertight?

Structural restoration

Any opening can weaken the element it passes through. The ANU roofing standard says that after coring or cutting, the structure must be restored to its original strength, with roof trimmers or soaker supports where needed. Large openings, or several holes close together, should be reviewed by the structural engineer before coring, not after. Cutting through reinforcement without sign-off is where problems begin.

Flashing and waterproofing

The NCC treats weatherproofing as a performance requirement, and the research behind the code’s provisions points to systems rather than patches. According to the NCC H2 weatherproofing part, flashing for penetrations should be purpose-made, with at least a 75 mm upturn and enough width around the penetration, and it must allow total drainage of the area above. For concrete roofs over internal spaces, materials and installation should align with AS 4654.1 and AS 4654.2.

The practical points a waterproofer will work to:

• Use a complete, compatible system: primer, membrane, flashing and sealant that suit each other and the substrate.
• Avoid caulking as the only defence. A bead of sealant around a pipe is a maintenance item, not a waterproofing system.
• Watch dissimilar metals. CSIRO’s APAS certification document covers damp-proof course and flashing materials, and corrosion between incompatible metals is a recognised failure point.
• Clear all metal swarf and debris from the roof straight away. The ANU standard notes that fillings and rivets left on the roof can corrode sheet material.

We do not apply membranes. Our role is to give the waterproofer a round, clean, correctly sized, correctly positioned hole, ideally with the sizes and tolerances they asked for.

Planning checklist for contractors and property managers

Use this list when you brief a coring contractor and your roofer together.

One more point on warranty: some roof membrane warranties are voided if unapproved trades penetrate the roof. Ask the roofer or membrane supplier what they require before you book the coring.

Common mistakes on roof coring jobs

• Coring first, asking later. A hole in the wrong place cannot be uncored. Fixing it means patching a structural slab.
• Holes too close to parapets, drains or each other. Flashing needs room to be detailed correctly.
• No plan for the core plug. Heavy plugs can drop through to the space below if not secured.
• Using roof space as an afterthought for plant. The ANU standard recommends against using roofs as plant areas; where unavoidable, a designed platform keeps penetrations to a minimum.
• Sealing with caulk alone. It looks finished on handover day and fails a season later.

Our perspective

We core roof slabs across Melbourne and Victoria, and the jobs that go smoothly share one trait: the people involved spoke to each other before the rig arrived. The coring contractor, roofer and engineer each hold a piece of the answer. We cannot tell you the right flashing detail, and the roofer cannot tell you what is inside your slab.

Our approach is to scan first, work to your site’s permit and SWMS process, use wet cutting or dust capture as the job requires, and leave a clean, accurately sized hole. We would rather move a core 100 mm after a scan than explain a severed conduit. If a requested location looks wrong to us, we say so before we start.

We also encourage clients to count their holes. If three small penetrations can be combined into one larger, well-flashed opening, the roof usually benefits.

— MYBMC

Cost and what affects it

We publish a range for concrete cutting of $450 to $5,000 per job, which reflects the spread between a few small holes and a larger, more complex scope. We do not publish a fixed price for roof coring, because the number depends on the factors that actually change the work:

• Slab thickness and bit diameter
• Quantity of holes
• Reinforcement density
• Access: stairs, hoisting or a crane
• Scanning requirements
• Dust and slurry controls, and out-of-hours work

The simplest way to get a firm figure is to send the number and size of holes, the slab type and any site rules, and we will quote against that.

Book roof coring in Melbourne

If you have a concrete roof or podium that needs penetrations, we can scan, core and leave the holes ready for your waterproofer. Our operators are licensed and qualified, and we work to OH&S safety standards on small domestic jobs and large construction projects alike. See our core drilling service or request a free quote with your hole schedule and site details. If you are working in the inner suburbs, our Richmond concrete cutting page has local details, and our Melbourne concrete cutting page covers larger projects.

FAQ

Can I core a hole in a concrete roof myself?

It is not advisable. You need to scan for cables and reinforcement, manage silica dust, and often hold a permit and SWMS. The hole must also be positioned and sized to suit the waterproofing. Hire a licensed operator and coordinate with your roofer.

Who is responsible for waterproofing after coring?

The roofer or waterproofing contractor, not the coring contractor. The coring crew provides a clean, correctly sized hole. The waterproofer then installs flashing and membrane as a complete system, in line with the NCC weatherproofing provisions and the relevant Australian Standards.

How deep is a typical roof core?

It matches the slab thickness, which varies by building and roof type. Many sites treat any penetration of 50 mm or more as high-risk work needing a permit and SWMS. A scan gives the real thickness before the job. See our guide on how deep you can core drill concrete.

Is wet or dry coring better on a roof?

Wet coring is the usual first choice because water suppresses silica dust at the source, but slurry must be contained. Where water is a risk, such as above sensitive equipment, dust capture with extraction is the alternative. Respirators alone are only acceptable where engineering controls are not reasonably practicable.

Sources

• Penetration, Coring & Concrete Cutting | Baseline
• Part H2 Damp and weatherproofing | WaterMark (NCC 2025)
• 05 – Roofing, Roof Fabric & Roof Safety | ANU
• Managing risks of respirable crystalline silica in the workplace | Safe Work Australia
• Silica | Safe Work Australia
• Guide to managing the risks of rooftop solar installation work | Safe Work Australia
• Product certification system, damp proof courses and flashing | CSIRO APAS

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• Manhole Core Drilling in Australia: No Entry Without a Permit

If you want to cut, lower or remove part of a kerb in Melbourne, you need your local council’s written permission before any saw touches the concrete. In most cases that means a vehicle crossing permit, which covers a new or modified driveway crossover. Where the work digs into the road reserve more broadly, a separate road opening or consent for works applies. This guide explains which one fits your job, what the City of Melbourne charges, what you have to submit, and how to sequence the cutting so the job passes inspection the first time.

One point of wording first. “Kerb cut” isn’t a formal permit name in Victoria. Councils call the permit a vehicle crossing permit (sometimes a crossover or driveway permit), and kerb and channel work is covered under it or under road works consent.

TL;DR

• A kerb cut for a driveway is normally approved as a vehicle crossing permit from the council that owns the road reserve. Cutting first and asking later risks fines and forced reinstatement.
• In the City of Melbourne, the application fee is $369.60 for a residential crossing and $580.70 for a commercial one. Both are non-refundable.
• Expect to supply a dimensioned site plan, engineering drawings, a Traffic Management Plan and public liability insurance. The City of Melbourne asks for a minimum of $20 million cover.
• The permit covers the public side only. Cutting on your own land is a separate job you coordinate yourself.
• Book the council’s pre-pour inspection. Pouring before it can mean ripping out your own concrete.

Table of Contents

• What a kerb cut permit actually is
• Which permit do you need?
• What it costs in the City of Melbourne
• What the council will ask you to submit
• Mistakes that delay or sink an application
• How the cutting fits into the permit timeline
• Why a licensed cutting crew makes the permit easier
• Our perspective on kerb cut jobs
• Get the cutting scoped alongside your permit
• FAQ
• Sources

What a kerb cut permit actually is

A vehicle crossing is the section of paving that connects the road to private property. It includes the part of a driveway that crosses a nature strip or footpath, and it ends at the kerb and channel. Cutting into that kerb to let vehicles through is therefore part of building or altering a vehicle crossing, and the City of Melbourne’s vehicle crossing page is the starting point for properties in its area.

Councils across Melbourne use near-identical logic with local variations:

• Boroondara requires a Vehicle Crossing Permit to remove, change, relocate, reinstate or construct a vehicle crossing.
• Kingston separates a Vehicle Crossing Permit (new crossings, repairs or changes) from a Road Opening Permit, which applies to any digging or excavation within the road reserve.
• Maroondah asks for written council consent and a permit for footpath or kerb and channel work as well as crossing repairs and new crossings.

The practical lesson: the council that owns the road in front of the property decides, and its rules and fees differ. Check the correct council before you budget.

Which permit do you need?

Match your job to the likely approval before you contact anyone.

The City of Melbourne also states that you must get permission and consent for road works before service works or excavation of any part of a footpath, road or kerb and channel, including parking bays and bicycle lanes. Its process starts with a letter to Council describing the property address, the works in the road reserve, the design details and proposed dates.

If you are unsure which row you fall into, phone the council before you pay anyone. A short call can save a rejected application.

What it costs in the City of Melbourne

As of this writing, the City of Melbourne’s published application fees are:

Both are non-refundable, so a rejected application still costs you the fee. For road alterations that go beyond a standard crossing, the council’s alterations page also lists an engineering plan review fee calculated as 0.75 per cent of the estimated construction cost of the public realm works. Check that page for current rates, because councils review fees regularly.

Other councils set their own fees, so don’t assume the City of Melbourne figures apply in Stonnington, Boroondara or Kingston. Those councils publish their own schedules.

The permit fee is only one line in the budget. You also pay for:

• Design drawings and a site plan
• A Traffic Management Plan
• Insurance certificates
• Concrete cutting and removal
• The new crossing construction and reinstatement

Our own published price range for concrete cutting jobs is $450 to $5,000 one-off, depending on scope, depth, access and length of cut. A single kerb section sits at the lower end, while a large commercial removal sits higher. We quote after we know the job.

What the council will ask you to submit

The City of Melbourne’s assessment typically involves a dimensioned site plan, engineering design drawings and a Traffic Management Plan (TMP). The council notes that heritage overlays or arterial roads can trigger extra approvals, such as a planning permit or authorisation from the Department of Transport.

Public liability insurance

For every vehicle crossing permit application in the City of Melbourne, you must provide a certificate of currency showing public liability insurance of at least $20 million for a single claim, with the City of Melbourne listed as an interested party. The council also explains what public liability insurance is for: covering compensation or costs when someone is injured or property is damaged through your negligence. If your contractor holds the policy, ask for the certificate before you lodge, and confirm the interested-party wording is right.

Site plan and engineering drawings

The plan must show dimensions, the proposed crossing, and how it meets the kerb, footpath and your boundary. Accurate drawings are the quickest way to move an application along, since the council’s priorities are public safety and pedestrian access. If your plan shows poles, street trees, pits or drains near the proposed opening, say so. These are common reasons for design changes.

Traffic Management Plan

A TMP describes how pedestrians and vehicles will be kept safe while you work. If the works need part of the footpath, road or a parking bay, the City of Melbourne’s occupy public space page says you must get a permit. Plan this at the same time as the crossing application so the two don’t contradict each other.

Mistakes that delay or sink an application

These come up repeatedly with council crossing work.

1. Assuming the permit covers everything. The permit applies to the council-managed road reserve. Work inside your property boundary, including the driveway surface on your side, is separate and you must coordinate it.
2. Missing neighbour consent. The City of Melbourne’s guidance flags written consent from an adjacent owner when works fall within 1000 mm (1 metre) of the boundary. Check your boundary against official records before you finalise the plan.
3. Expecting the council to pay. The vehicle crossing is the property owner’s responsibility, including maintenance, repairs and meeting engineering design standards.
4. Skipping the pre-pour inspection. Yarra City Council describes a vehicle crossing as the portion of driveway between the property boundary and the road, and inspectors there check formwork and reinforcement before concrete goes in. Pour early and the council can require removal at your cost, even if the finished concrete would have met the design.
5. Cutting before approval. Failing to follow council requirements can lead to permit refusal, fines and an order to reinstate the infrastructure.

How the cutting fits into the permit timeline

The order matters more than most owners expect. A workable sequence looks like this:

1. Confirm which council owns the road and what permit it requires.
2. Get a concrete scan or site check so drawings reflect what is under the surface.
3. Prepare the site plan, engineering drawings, TMP and insurance certificate.
4. Lodge the application and pay the fee.
5. Receive approval and read the conditions, including time limits and reinstatement requirements.
6. Book the cutting crew and any traffic control for the approved dates.
7. Cut and remove the kerb and old crossing, then prepare the formwork and reinforcement.
8. Book and pass the council’s pre-pour inspection.
9. Pour, finish and complete any permanent reinstatement within the permit’s time frame.

The City of Melbourne’s standard permit conditions say permanent reinstatement is to be completed within two months of temporary reinstatement, to the council’s satisfaction and standards. Read your own permit, because conditions can vary by job.

Why a licensed cutting crew makes the permit easier

A council permit says you may do the work. It doesn’t say the work will be accurate, safe or tidy. Saw-cutting a kerb and channel needs clean lines so the new crossing meets the road surface neatly, and the cut has to stay within the approved footprint. Over-cutting leads to patching, and patching leads to a failed inspection.

The method depends on the setting:

• Road and kerb edges: road sawing gives straight, controlled cuts through concrete and asphalt next to live traffic and pedestrian paths.
• Removing the old crossing: concrete removal takes out the old slab in sections, which limits dust and vibration near neighbours.
• Unknown ground: concrete scanning before cutting helps locate reinforcement and services, so the cut doesn’t hit something you didn’t plan for.

If you’re weighing whether to hire a pro, our guide on the benefits of hiring concrete cutting in Melbourne sets out the safety and quality reasons in more detail.

Our perspective on kerb cut jobs

Most of the delays we see on kerb and crossover work aren’t about the cutting. They come from the paperwork running behind the programme. A crew booked for Monday and a permit that arrives the following month is a common and expensive mismatch.

We work across Melbourne and Victoria with licensed, qualified operators, and we run every job to OH&S safety standards, whether it’s a small domestic crossover or part of a large construction project. For kerb work, that means three habits. We confirm that approval is in place and read its conditions before we mobilise. We scan or inspect the area before cutting. And we mark the cut lines against the approved drawings so the inspector sees what the plan promised.

We don’t lodge council permits for you as a service we advertise, so we won’t claim that. What we do is give builders, property managers and homeowners a clear cutting scope and quote that fits the permit timeline. That makes it easier to schedule the sequence above without idle days.

— MYBMC

Get the cutting scoped alongside your permit

If you’re planning a crossover, driveway widening or kerb alteration anywhere in Melbourne, talk to us about concrete cutting while your application is being prepared. Tell us the address, the council, the approximate length of cut and whether the surface is plain or reinforced concrete. We’ll give you a free quote and a realistic window that lines up with your approval and inspection dates. For road-edge and kerb cuts specifically, see our road sawing service.

FAQ

Do I need a permit to cut a kerb for a driveway in Melbourne?

Yes. The kerb belongs to the road reserve, which is managed by the council, so you need its written consent before cutting. Most councils process this as a vehicle crossing permit. Cutting without one can lead to fines and an order to reinstate the kerb at your cost.

How much is a kerb cut permit in the City of Melbourne?

The City of Melbourne lists an application fee of $369.60 for a residential vehicle crossing and $580.70 for a commercial one, both non-refundable. Other councils set different fees, and road alteration work can attract an engineering plan review fee. Confirm the current amount with your council before lodging.

Who does the work after the permit is approved?

You, as the property owner, are responsible for the crossing and for arranging a contractor. The permit covers the public side only, so any work inside your boundary is organised separately. The crew you hire should work to the approved drawings and conditions.

Can I pour the new crossing straight after cutting?

No. Councils inspect the formwork and reinforcement before the concrete goes in. If you pour before that inspection, the council can require you to remove the concrete at your own expense. Book the inspection as soon as the preparation is done.

Does a property on a main road need anything extra?

Possibly. For arterial roads, the City of Melbourne notes that extra authorisation from the Department of Transport may be required alongside the council permit. Heritage overlays can also trigger a planning permit. Raise both with the council at the start.

Sources

• Vehicle crossings (driveways and crossovers), City of Melbourne
• Alterations to road infrastructure, City of Melbourne
• Occupy public space for construction or maintenance, City of Melbourne
• Public liability insurance, City of Melbourne
• Vehicle Crossing Permit summary and Conditions, City of Melbourne
• Permanent vehicle crossings, Yarra City Council
• Vehicle Crossing Permit, City of Boroondara
• Vehicle crossing and road opening permits, City of Kingston
• Vehicle Crossing Permit Application, Maroondah City Council

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A concrete doorway opening is a structural change, not a cutting job. The saw cut takes hours. The planning that comes first (permit, engineer’s design, scanning, lintel and finishing) decides whether the opening is safe, legal and square. This guide walks you through that sequence for walls in Melbourne and the rest of Victoria, so you know what to ask for and what to expect from the contractor you hire.

TL;DR

• In Victoria, a new door or a change to the width or height of an existing door frame almost always needs a building permit. Get it before work starts.
• Measure the clear opening, not the door leaf. New homes under the National Construction Code need an 820 mm clear width for key internal doorways.
• Scan the wall for rebar, conduit and services before any blade touches it. Never rely on drawings alone.
• The lintel (header) goes in before the full opening is cut, so the wall above is never unsupported.
• Wet cutting or dust extraction is part of the job, not an extra.

Table of Contents

• What a concrete doorway opening involves
• Do you need a permit in Victoria?
• Measuring the opening correctly
• Scan before you cut
• Lintels, headers and the order of work
• Choosing the cutting method
• Dust, water and safety on site
• Framing, finishing and the door itself
• Our view: the cut is the easy part
• What a doorway cut costs
• Getting the opening cut
• FAQ
• Sources

What a concrete doorway opening involves

An opening in a concrete or concrete block wall removes a section of material that may be carrying load from the floors, roof or wall above. That load has to be redirected around the opening and down into the wall on either side. Whether you are connecting two rooms, adding a basement walkout, opening a garage to an extension or creating a new entry to a warehouse bay, the same four questions apply:

1. Is the wall load-bearing, and what is above it?
2. What is inside it (reinforcement, conduit, pipes, post-tensioned cables)?
3. What size must the finished opening be, once framing and finishes are in?
4. Who approves the work, and who is licensed to do it?

The rest of this article answers those in order.

Do you need a permit in Victoria?

In most cases, yes. Victorian council guidance says you need a building permit if you are installing a new door or changing the width or height of an existing door frame. The reason is that the work alters the structural soundness of the building or affects essential safety measures. The permit requirement sits under the Building Act 1993 and the Building Regulations 2018. The main exception is replacing a door with a similar one without structural change, which is not what a new opening involves.

Councils make the same point more broadly: a permit must be in place before works commence for most alterations. In practice that means:

• Engage a structural engineer for any load-bearing wall, tilt-panel, retaining wall or foundation wall. The engineer specifies the lintel or steel beam, the bearing length and any propping.
• Give the permit documents to a registered building surveyor, who issues the permit and inspects stages of the work.
• Book your cutting contractor only once the approved design is in hand, so the saw cuts match the drawings.

If you are a property manager or facility manager, check lease conditions and any owners corporation rules as well. Planning overlays and heritage controls can apply separately from the building permit, so ask your local council.

Measuring the opening correctly

Most mistakes with concrete openings come from measuring the door instead of the space the door needs. Concrete cannot be added back easily, so the cut should be set out from the finished dimensions and worked backwards.

Start with the clear opening

For new homes and apartments, the National Construction Code’s Livable Housing Design Standard requires internal doorways on the main access paths to have a minimum clear opening width of 820 mm. A single swinging door with an 820 mm clear width can generally be achieved with an 870 mm door leaf. The same standard calls for thresholds that are level, or have a lip of no more than 5 mm if rounded or bevelled, or a ramp no steeper than 1:8. It also expects connected corridors to be at least 1000 mm wide. Whether the standard applies to your project depends on the building type and whether the doorway is on a path to the rooms it covers, so confirm with your designer or surveyor.

Work out the rough opening

The rough opening is the hole in the wall. It has to be larger than the clear opening to allow for:

• The door frame and jambs (timber, steel or aluminium)
• Packing and fixing tolerance around the frame
• Any lining, render or tiling returned into the reveal
• The lintel or beam depth above the head, which is set by the engineer, not by the door

A practical approach is to list every layer on each side and add them to the clear width, then do the same for height. Check the floor finish too. If you are tiling or laying timber later, measure to the finished floor level so the door does not end up short or dragging.

Check the wall thickness

Concrete walls vary: 100 to 200 mm in many residential and tilt-up applications, thicker in foundation walls and some commercial structures. Wall thickness determines which cutting method is practical, which is covered below. Measure it at an existing opening, a penetration or the wall end, not by guessing.

Scan before you cut

Never assume the wall is plain unreinforced concrete. Even residential walls can contain rebar, post-tensioned tendons or electrical conduit. Professional cutters scan every saw line or core position with ground penetrating radar (GPR) and cable-avoidance tools. That protects people from live services, and it protects the diamond blades from unexpected steel.

Two checks belong together:

1. A Before You Dig Australia (BYDA) search for external or underground services near the wall.
2. On-site scanning of the wall itself, because as-built conditions often differ from the plans. Industry safety requirements treat BYDA plus on-site scanning as the baseline before structural penetrations, and warn against relying on drawings alone.

Scanning results go to the engineer. If the scan finds heavy reinforcement or tendons in the planned line, the opening position or the cutting method may change. Better to learn that on a scan than mid-cut.

Lintels, headers and the order of work

The saw cut is the most visible part of the project, but the real engineering is at the head of the opening. A header carries the load from the wall above down to the jambs. In concrete and masonry it is typically a steel beam set into grouted pockets or a reinforced concrete lintel poured in place. Shortcuts here lead to cracking, doors that stick and failed inspections.

The sequence matters

The safe order is to form the lintel pocket and install the lintel first, then cut the full opening below it. Reversing that leaves the wall above temporarily unsupported, which can cause cracking, dropping or collapse. The lintel also needs enough bearing on the wall at each side to spread the load properly. Your engineer sets that length.

Watch for the bond beam

In concrete block (CMU) walls, the top course is often a grouted bond beam that ties the wall together. Cutting through it without knowing what sits above and without shoring can let the wall above shift. Professionals recommend identifying the bond beam before marking any cuts. If your opening reaches that course, the engineer needs to see it.

Typical order of work

1. Engineer’s design and building permit.
2. Scanning and service location; mark the opening on the wall.
3. Install temporary propping where the engineer specifies.
4. Cut and form the lintel pockets; install the lintel or beam.
5. Cut the opening with the agreed method, removing the concrete in sections.
6. Core out corners if the design calls for over-cut-free corners.
7. Clean up slurry and dust, then hand over for framing and finishing.

Choosing the cutting method

Different walls call for different equipment. The method affects accuracy, noise, dust and how the offcut pieces come out.

For most doorway openings through reinforced concrete walls, wall sawing gives the cleanest result because the saw runs on a rail fixed to the wall. That means straight lines, square corners and consistent edges, which makes framing the door much easier. For very thick or restricted sections, wire sawing is the alternative. Where noise, vibration or access are concerns, ask about low-vibration methods. Cutting also avoids the impact shock that a jackhammer sends through the structure, so the surrounding wall stays intact.

If the offcut is heavy, tell your contractor how it must come out. A section of 200 mm concrete weighs a lot, and the plan for lifting and removing it (cut into smaller pieces, or slid out on a rail) belongs in the method statement. Our concrete removal service covers breaking down and taking the material away.

Dust, water and safety on site

Cutting concrete releases respirable crystalline silica, which can cause silicosis when workers breathe it over time. The best control is wet cutting, where water suppresses dust at the blade. If you have to cut dry, the dust must be captured with M-Class extraction rather than left to settle. We explain the difference in more detail in our guide on wet versus dry cutting in Australia, and on our page about dustless concrete cutting in Melbourne.

For homeowners and occupiers, this has practical consequences:

• Ask how slurry will be contained and removed, particularly indoors.
• Seal doorways and vents to rooms you are not working in, and cover flooring.
• Keep children, pets and anyone with respiratory conditions out of the work area.
• Expect a written safe work method statement (SWMS) from a professional contractor before work begins.

Exposure limits for silica are changing in Australia, with a transition from workplace exposure standards to workplace exposure limits. Contractors should be working to the current requirements of the regulator in their state, so ask which standard the job is planned to.

Framing, finishing and the door itself

Once the opening is cut, the work shifts to the carpenter, builder or door installer. A few things to settle early.

Frames and facing

The cut edges of concrete are rough and rarely perfectly plumb, so frames are fixed with packers and shims and the gap is sealed. In block walls, one common option is to face the opening with treated timber that sits close to the wall width, so the frame has something solid to fix to. Steel frames can be anchored directly into the concrete with masonry anchors. Check that fixings are set away from the edge, because anchors placed too close can spall the concrete.

Fire-rated and commercial doors

If the opening is in a fire-separating wall, in a plant room or in a commercial or industrial building, the door and frame may need a fire rating. That means a certified door set, not an ordinary timber frame. Suppliers who make fire-rated steel doors and hollow metal frames, such as this manufacturer of fire-rated steel doors and commercial door hardware, show the range of products and certifications involved, though you should check Australian standards and your surveyor’s requirements before choosing a product.

Thresholds and floor levels

A threshold that sits proud of the floor is a tripping hazard, and a common reason people want to cut the slab below a door. If the floor level changes, the engineer needs to approve any cutting of footings or slab edges. Where accessibility matters, design to the level threshold or ramp limits in the Livable Housing Design Standard from the start.

Outdoor openings and archways

External openings, such as a side entry to a garage, a gate in a boundary wall or a walkout from a basement, add drainage, waterproofing and weather sealing to the list. A new external opening in a retaining or foundation wall needs special care because soil pressure acts on the wall. Archways are also possible, because a curved head is cut by drilling a series of cores and sawing between them, but the arch needs its own structural design and often a steel support behind the finish.

Our view: the cut is the easy part

We cut openings in concrete walls across Melbourne and Victoria, for homeowners, builders, property managers and industrial sites. The pattern we see is consistent: the jobs that go smoothly are the ones where the engineer’s drawing, the permit and the scan results are in hand before we set up.

Three things we ask every client:

• Has the wall been scanned? We scan as part of the job, because drawings do not always match what was built.
• What is the lintel detail and who supplies it? If the beam arrives late, the cutting waits, and rushing the support is never acceptable.
• Where does the dust and water go? We plan for wet cutting or extraction, and for slurry removal, before we start.

Our operators are licensed and qualified, we work to OH&S safety standards, and we handle everything from small domestic tasks to large construction projects. A door opening is usually a modest job for us, but we treat it with the same process as a commercial one: assess, scan, plan, cut, clean up.

— MYBMC

What a doorway cut costs

The price depends on wall thickness, reinforcement, access, the opening size, whether the work is inside or outside, and how the concrete must be removed. Our published range for concrete cutting is $450 to $5,000 per job, and we quote each project after we understand the wall. Remember that cutting is one line in the budget. Engineer’s fees, the building permit, lintel supply, framing, the door, making good and painting sit alongside it.

To keep the quote accurate, give the contractor:

• Photos of both sides of the wall
• The wall thickness and material (poured concrete, block, tilt panel)
• The desired opening size and position
• The engineer’s drawing, if you have it
• Access details: stairs, tight lanes, upper floors

Getting the opening cut

If you have an engineer’s design and a permit, or you need help working out what the wall needs, we can scan, cut and remove the concrete. Our wall sawing service is built for doorway openings, and the main Vic Sawing & Drilling site lists concrete cutting, concrete scanning and robotic demolition for larger jobs. We work across Melbourne, including Richmond, Werribee and Sunbury, and regional Victoria. Ask for a free quote and we will tell you plainly what the job involves.

FAQ

Can I cut a doorway in a load-bearing concrete wall myself?

We do not recommend it. The wall carries load, so the opening needs an engineer’s design, a lintel and usually a building permit. Cutting also needs scanning, propping and silica controls. Hire licensed operators with the right saws and extraction.

Do I need a permit to widen an existing door opening?

In Victoria, changing the width or height of an existing door frame generally requires a building permit. Check with your council or a registered building surveyor before you book the work.

How wide should the opening be?

For new homes under the National Construction Code, key internal doorways need an 820 mm clear width, usually an 870 mm door leaf. The rough opening must be larger to fit the frame and packing, so set it out with your builder.

What if there is steel in the wall?

Most structural concrete has rebar, and diamond blades and wire are designed to cut through it. What matters is knowing where it is. Scanning shows the layout so the engineer and cutter can plan around tendons, conduit and heavy bars.

Is cutting concrete messy?

Wet cutting produces slurry, but it keeps dust down and it can be contained and removed. Dust extraction is the alternative where water is not suitable. Either way, ask your contractor how they will protect the area.

Sources

• Do I Need a Building Permit? Hume City Council
• When a building permit is required, City of Greater Geelong
• Part 3 Internal doors and corridors, ABCB
• Designing livable and accessible bathrooms, KBDI
• Cutting a Doorway in a Foundation Wall
• Cutting a Door Opening in a Concrete Wall Safely and to Code
• Core Drilling for Construction Contractors
• HSEQ Requirements, Ertech Group

Recommended

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

Manhole core drilling is high-risk construction work, so before any bit touches the wall, you need a SWMS, a confined-space permit and a documented atmospheric test. Run the rig wet with a continuous water feed, capture the slurry with a wet vacuum, and fix a hydraulic or electric rig to the structure. If any of those controls is missing, stop and call a licensed coring contractor.

TL;DR:

• Keep the gas monitor running throughout drilling, record readings and test times on the permit, and assign an attendant outside the chamber.
• Use continuous water delivered to the cutting face and a wet vacuum to capture slurry; a spray bottle or garden hose is inadequate.
• Scan for utilities and reinforcement, verify the structure, then drill a pilot hole; stop and escalate if it reveals an obstruction or mismatch.
• Confirm the boot or sleeve diameter and manufacturer’s tolerance before drilling, then measure the finished opening and test watertightness under expected pressure.
• Use a licensed coring contractor for large diameter holes, confined chamber entry, complex sealing, or work requiring authority approval before crews or equipment are committed.

Table of Contents

• When side-wall coring is the right way into a manhole
• What to complete before you drill
• Confined-space controls that apply to manholes
• Choosing the rig, bits and setup
• Step-by-step side-wall coring procedure
• Slurry capture and dust control
• Sealing the penetration and finishing the opening
• Fixing common coring problems fast
• Where an in-house crew should hand over to a specialist
• Hiring a coring team for manhole work
• FAQ
• Sources

When side-wall coring is the right way into a manhole

Side-wall coring lets you create a new opening in an existing chamber without excavating the whole structure. That is why it suits trenchless work, where the goal is to connect or pass services with minimal surface disruption. Before you commit to it, check the site against these common uses and constraints:

• Service entry and exit: new incoming pipes, outlet relocations and access points for trenchless crews.
• Trenchless pipe connections: a cored opening gives the pipe a clean, round, close-tolerance seat for a boot or sleeve.
• Internal fittings: steps, ladders, existing inverts and benching limit where the rig can sit and how large the hole can be.
• Invert level and flow: the new opening needs to sit above or clear of live flow, and the benching shape decides how the mast can be braced.
• Wall thickness and reinforcement: thick or heavily reinforced walls change the bit choice, the feed rate and the time on site.

As a quick test, side-wall coring is usually the right call when the opening is round, the wall can carry the rig’s reaction load, and you can reach the cutting face with a secured mast. If the opening needs to be rectangular, the wall is structurally doubtful, or the chamber is too small to brace a rig, another access method may be safer. If the chamber is also hard to enter, our notes on concrete drilling in tight spaces cover the setup problems you will meet.

What to complete before you drill

Paperwork comes first because it decides whether the job can legally start. Work through this sequence in order:

1. Prepare a SWMS. Treat the coring as high-risk construction work and document it in a safe work method statement that covers the confined space, the silica hazard and the plant being used. If you are unsure which safety document your site needs, this guide to SWMS versus JSA requirements explains the difference.
2. Raise the confined-space permit. A manhole that looks dry is still a confined space, and the permit must be in place before anyone enters.
3. Locate services. Scan the wall and surrounding slab for electrical conduits, reinforcement and other utilities, then mark the position.
4. Verify the structure. Compare the position against drawings, or get an engineer’s sign-off for the penetration. Large contractor standards also require a permit for any penetration into concrete and a pilot drill to confirm the core location, as set out in one major contractor’s penetration standard.
5. Obtain authority approvals. Where the chamber belongs to a water or sewer authority, get written approval before you modify it.
6. Coordinate with the principal contractor. Agree the exclusion zone, the isolation of flow if any, and who signs off the finished opening.
7. Plan the next trade. If pipe installation or relining follows the coring, confirm the opening size with that crew. Specialists such as Priority Plus Plumbing handle relining of cracked or misaligned pipes, and agreeing tolerances early avoids a second cut.

The competency standard behind this work, unit CPCCON3057, expects the operator to select and set up the coring system, set out the hole with correct measurements and calculations, and work within WHS and environmental requirements. If your operator cannot show those skills, the job is not ready to start.

Confined-space controls that apply to manholes

A dry-looking manhole is not a safe one. Hydrogen sulfide and methane can be present without any visible sign, so WorkSafe guidance requires atmospheric testing and a documented entry permit before entry. Apply these controls on every job:

• Test the atmosphere: check oxygen, hydrogen sulfide, methane and other toxic gases before entry, and keep monitoring while work is under way.
• Record the results: the permit should show the readings, the time and who took them.
• Ventilate: use forced ventilation to keep air moving, and keep intakes clear of vehicle and generator exhaust at street level.
• Choose the power source carefully: hydraulic and electric rigs avoid the exhaust that a petrol engine puts into an enclosed chamber.
• Control silica: silica-containing materials such as concrete release hazardous dust when cut, so follow Safe Work Australia’s silica guide, which prescribes wet cutting and local exhaust ventilation as engineering controls.
• Select respiratory protection: wear RPE suited to the exposure, fit-tested to the person wearing it.
• Keep records: retain the permit, test readings, exposure controls and equipment checks with the SWMS.

Where enclosed-space work and silica exposure overlap, as they do inside a chamber, controls at the source matter more than protective equipment worn afterward. Our own guidance on wet versus dry cutting explains why wet methods come first.

Pro Tip: Leave the gas monitor running for the whole drilling period and assign one person outside the chamber to watch it. A clean reading at one point says nothing about how the air may change later.

Choosing the rig, bits and setup

In a confined chamber, hydraulic and electric rigs are the working choice, and internal-combustion engines are avoided because their exhaust can quickly deplete oxygen. Set up the rig in this order and check each point before you start:

• Mounting: use a drill stand or mast with anchor bolts into sound concrete, and follow the manufacturer’s instructions for fixing. The industry standard for safe concrete cutting and drilling requires secured drill stands with anchor bolts.
• Bit selection: match diamond core bit diameter and length to the hole and the wall depth. Manufacturers publish the diameter ranges commonly available for manhole work, as in this diamond core drill range, and they reference the close tolerances that seal installation depends on. Our note on how deep you can core drill concrete helps when wall depth is in question.
• Couplings and fitment: quick-change couplings speed up bit changes, but confirm the bit seats true before every start.
• Water feed: supply continuous, multi-feed water to the cutting face. The industry standard also calls for feeding tap water into the hole to flush slurry.
• Electrical safety: use IP-rated equipment, check safety tags, and confirm RCD protection on every lead.
• Slurry extraction: connect a wet vacuum to the water feed so slurry is removed as it forms, and fit overfill protection to the vacuum pump.

Heavy in-plant machines are a different category. Production machines such as the Core-Matic and the Hydrokor III are built for factory throughput with multiple spindles and heavy hydraulic power, so they do not represent what you will carry down a shaft. On site, the field rig is the one you can brace, power and extract from safely.

Step-by-step side-wall coring procedure

Follow this sequence for each opening, and stop at any step where the result does not match the plan:

1. Mark the hole. Set out the centerline and diameter from the approved position, checking measurements twice.
2. Drill a pilot. A pilot hole confirms alignment and can reveal hidden reinforcement or services. If something unexpected appears, stop and escalate.
3. Secure the mast. Install the anchors, tighten the stand and check for movement by hand before connecting power.
4. Barricade and prepare water. Set up barricades, connect the water feed and confirm the wet vacuum is working.
5. Start in low gear. Begin slowly so the bit seats without wandering, with water already flowing.
6. Increase feed gradually. Raise feed pressure as the bit takes hold, keeping the cutting face cool with continuous water.
7. Manage torque. If the motor labors or the rig shudders, ease the feed and check for binding before continuing.
8. Release the core safely. Support the plug before it frees, since it can drop or jam, and remove it with proper handling.
9. Cover the opening. Protect any open penetration temporarily so no one can fall or drop material through it.
10. Check and document. Measure the hole against tolerance, prepare it for the boot or sleeve, and record the work against the SWMS.

Pro Tip: Count on the core plug being heavy. Rig a sling or catch plate before the bit breaks through, so the plug is controlled the moment it releases.

One more rule from the industry standard deserves repeating: do not drill inverted holes with electric drills unless they are fitted with a water-collection ring. Water running back toward the tool is an electrical hazard as well as a mess. Our overview of core drilling techniques adds detail on feed control and bit behavior.

Slurry capture and dust control

Water delivered to the cutting face is the first line of defense, and it has to be continuous. Safe Work Australia is clear that dry cutting without extraction or water suppression produces very high exposures, and a handheld spray bottle or a garden hose does not meet that need. Use these practices on every job:

• Multi-feed water: deliver water directly to the cutting face for the whole run, not intermittently.
• Source extraction: a wet vacuum removes slurry before it dries, which prevents respirable silica becoming airborne again.
• Pump placement: position the pump where it stays accessible and cannot be flooded, and check intake screens during the job.
• Pump maintenance: keep spare filters on hand and empty the tank before it reaches capacity.
• Clean-up: wash down and vacuum residue at the end of each session so dried slurry does not become dust underfoot.
• Disposal: collect and dispose of slurry in line with environmental requirements, never into stormwater or the open sewer.

Silica warning: Safe Work Australia states that dry cutting, grinding or polishing silica-containing materials without appropriate extraction or water suppression generates very high exposures. Wet methods are the baseline, not an upgrade.

For extra detail on reducing airborne dust, see our tips on minimizing dust when sawing concrete and how we capture dust at the source.

Sealing the penetration and finishing the opening

A cored opening is only finished when it holds water out. Trenchless connections need design verification that the seal will stay watertight under the expected hydrostatic pressure, as trenchless installation guidelines emphasize. Work through these checks:

• Match boot to core: choose a boot or sleeve sized to the cored diameter, and confirm the seal manufacturer’s tolerance before you drill.
• Check the hole: measure the opening and clear any chips or slurry film from the wall so the seal bears on clean concrete.
• Grout correctly: where grout is part of the design, fill the annulus fully and let it cure as specified.
• Test the result: confirm watertightness with a pressure or leakage check suited to the hydrostatic conditions on that line.
• Protect and reinstate: guard the opening until the pipe is placed, then restore benching, step access and the surrounding surface.

If the finished opening misses tolerance, fix it before the pipe goes in. A boot forced into an oversize hole will not seal, and the repair costs far more than a careful measurement.

Fixing common coring problems fast

Most problems on a manhole job trace back to water, anchoring or surprises in the wall. Use these corrective steps:

• Vacuum loss or clogging: isolate the pump, clear the lines, and swap filters. Keep spares and an overflow plan so slurry never reaches the chamber floor unchecked.
• Excessive vibration or binding bit: stop and check anchors and alignment first. Then reduce the feed rate or change to a different bit profile.
• Obstruction after the pilot: stop work, notify the principal contractor or utility owner, and have an engineer assess before cutting further.
• Water in the wrong place: if water or slurry tracks toward electrical equipment, cut power and reposition leads and collection before resuming.

Do not push through any of these. An unexplained change in how the rig behaves is information, and the pilot hole exists precisely to deliver it early.

Where an in-house crew should hand over to a specialist

Our team works from a safety-first approach to manhole coring, and our view is blunt: the line between in-house capability and specialist work is drawn by risk, not pride. Call a licensed coring contractor for large-diameter holes, any entry into a confined chamber, complex sealing, or any job that needs authority approval. We are glad to assess the complexity of your site and provide a quote before you commit crews and plant.

— MYBMC

Hiring a coring team for manhole work

When the permits, the confined space and the sealing all sit on one job, handing it to a specialist removes most of the compliance load from your site. Our core drilling service is built around that:

• Licensed operators: qualified crews who work to OH&S safety standards on commercial and industrial sites.
• Wet slurry containment: we focus on safe, quality outcomes.
• Confined-space discipline: we work with safety in mind.
• Core drilling: we provide core drilling for your project.

We focus on safe, quality outcomes for your project. To request a site visit or a quote, contact us through our concrete drilling page.

FAQ

What does it mean to core a hole?

Coring a hole means cutting a cylindrical opening with a hollow diamond bit, which leaves a solid plug of material called the core. It produces a clean, round, accurate hole, which is why it suits manhole walls where a boot or sleeve must seal tightly.

What is the best way to drill a hole in a cement block?

Use a diamond core bit or a masonry bit on a rotary drill, and suppress dust with water where the material contains silica. For a manhole wall, secure the rig to the structure first, because a loose rig will bind and wander.

What are three types of drilling methods?

Three common concrete drilling methods are rotary hammer drilling for small holes, diamond core drilling for clean round openings, and rock drilling for harder ground. For manhole side walls, wet diamond core drilling is the standard choice because it controls dust and holds tolerance.

What are the available sizes for core drilling?

Diamond core bits come in a wide range of diameters, and manufacturers publish the ranges used for manhole coring. Pick the size from the pipe and the boot or sleeve specification, then confirm that the rig and wall depth can handle it.

Sources

• Worksafe
• Safe concrete cutting and drilling
• Working with silica and silica containing products
• Worksafe
• National Training Register - CPCCON3057 Core concrete

Recommended

• Concrete Drilling Melbourne: Top Rated Concrete Drilling Company
• Rock Drilling & Industrial Drilling in Melbourne

Yes, you can cut a recess in a concrete slab to create a flush shower entry or a seated fixture, and it’s one of the most reliable ways to get a true curbless result compatible with in-slab heating. Typical recess depth runs about 1.5 to 2 inches, enough room for slope, a waterproofing membrane, and the tile bed. The alternative, building up the surrounding floor instead, skips the cutting but leaves a transition step at the door.

TL;DR:

• A curbless shower recess typically needs 1.5 to 2 inches for the slope, waterproofing membrane, and mortar or tile bed.
• Scan the slab for reinforcement and services before cutting; post tensioned or heavily reinforced slabs may require an engineer’s approval.
• WorkSafe Victoria requires water suppression at the tool or extraction connected to a Dust Class H vacuum, plus a SWMS before high risk cutting.
• Building up the surrounding floor avoids cutting but leaves a doorway step; recessing adds removal, drain, waterproofing, and tile costs, and drain changes may require permits.

Table of Contents

• Steps to recess a concrete slab the right way
• Which tools and methods fit your recess job?
• Cutting technique that avoids rework and damage
• What dust control and paperwork does this job require?
• Should you recess the slab or build up the floor instead?
• How Vic Sawing & Drilling approaches a recess cutting job
• Where most recess cutting advice gets it wrong
• Getting a quote for your recess cutting project
• FAQ
• Sources

Steps to recess a concrete slab the right way

Getting a clean, code-ready recess comes down to sequence. Skip a step and you’ll likely redo work later, especially around drains and slope.

1. Measure and mark the recess footprint on the slab, then scan for rebar, conduit, or plumbing lines before anything touches the surface.
2. Confirm drain position and slope so you know exactly how deep to cut. Most curbless showers need 1.5 to 2 inches of depth to fit a 1/4 inch per foot slope, a waterproofing membrane, and the mortar or tile bed on top.
3. Cut the perimeter with a saw fitted with a diamond blade matched to the slab’s aggregate, using step cutting (several shallow passes) rather than one deep plunge.
4. Remove the interior concrete with a rotary hammer or jackhammer once the perimeter is scored to full depth, then clear debris and check the base is flat and sound.
5. Prepare the base for a mortar bed or a pre-sloped shower pan, confirming the subsurface can support the finished assembly.
6. Install waterproofing, let it cure per the manufacturer’s instructions, then test the slope toward the drain with a straightedge and a small amount of water before you commit to tile.

Trade how-to references describe this same core sequence: score the perimeter, break out the interior, and prep the base before setting a pre-sloped pan or mortar bed. For a worked example of slab cutting on a real project, our guide to cutting balcony concrete walks through a similar depth-and-removal sequence outdoors.

Which tools and methods fit your recess job?

Tool choice depends on the shape of the recess, the depth you need, and how much dust control the site demands.

• A 230 mm (9 inch) angle grinder fitted with a recess disc or a wheel-bearing guide works well for circular cuts, especially puddle flange recesses around a shower drain.
• A walk-behind or larger floor saw suits long, straight perimeter cuts or deeper recesses where a handheld grinder would take too many passes.
• A rotary hammer or jackhammer handles bulk removal once the perimeter is scored, breaking out the interior concrete without disturbing the finished edge.
• Dedicated recess kits, built from diamond discs, shrouds, and extraction ports, cut a full flange recess in one pass. 200 mm puddle flange recess kits sold in Australia pair a centering bearing with a dust shroud for consistent, repeatable results.
• Pair any of these tools with on-tool water suppression or dust extraction rather than cutting dry.

Pro Tip: For repeat jobs like multiple bathroom renovations, a dedicated puddle flange kit saves far more time than freehand grinding and gives you a more consistent edge every time.

Our guide to concrete sawing breaks down blade and saw selection in more depth if you’re choosing equipment for the first time.

Cutting technique that avoids rework and damage

The depth of your cut matters as much as the tool you use to get there.

• Cut in shallow passes of about 0.5 inch (12 to 13 mm) each, working down to full depth rather than forcing a single deep plunge.
• Choose a continuous rim blade for clean, chip-free edges or a turbo or segmented blade when speed matters more than finish.
• Let the saw run at its rated speed. Forcing it causes blade burn, binding, and a rougher cut that needs more cleanup.
• Score a clean perimeter first and back-chisel stubborn edges by hand to prevent spalling at the cut line.
• Dry-fit the drain flange or fixture several times before the final trim so you’re not cutting corrections into finished waterproofing later.

What dust control and paperwork does this job require?

Cutting concrete releases respirable crystalline silica, and the controls aren’t optional. WorkSafe Victoria’s industry standard requires engineering controls, either on-tool water suppression or on-tool extraction connected to a Dust Class H vacuum, along with a Safe Work Method Statement (SWMS) for high-risk cutting work.

• Choose wet or extracted cutting every time. WorkSafe guidance confirms that cutting, grinding, or drilling silica-containing materials generates airborne dust that needs on-tool controls to manage.
• Write a SWMS before starting and coordinate the timing with any plumber or electrician working nearby. Our SWMS guide for concrete cutting covers what the document needs to include.
• Contain wet-cutting slurry so it doesn’t dry out and become airborne dust again; wet and dry vacuums handle this cleanup efficiently.
• Set up PPE and an exclusion zone: respirators, eye and ear protection, and attention to electrical safety if you’re running a petrol saw versus an electric one indoors.
• Stop work if you hit rebar or post-tensioning cables you weren’t expecting, and get a structural engineer or a licensed cutter to assess before continuing.

Dust control compliance is not a guideline you can skip. WorkSafe Victoria’s standard makes on-tool suppression or extraction a mandatory control for concrete cutting, not an optional precaution. Our breakdown of wet versus dry cutting shows how much dust wet methods remove compared with dry grinding.

Should you recess the slab or build up the floor instead?

Both paths get you a usable shower or fixture base, but they carry different structural and budget consequences.

1. Weigh the structural impact. Recessing gives the cleanest flush result; building up the surrounding floor avoids cutting into the slab but creates a step at the doorway.
2. Check the slab type first. ACI 360R-10 outlines how reinforcement and slab design affect what you can safely cut into, and a post-tensioned or heavily reinforced slab usually needs an engineer’s sign-off before any cutting starts.
3. Budget for the full scope, not just the cutting: site access, concrete removal and disposal, a plumber for drain relocation, waterproofing, and tile labor all add to the total.
4. Confirm permit requirements with your local building authority if the job involves relocating a drain or altering waterproofing membranes.
5. Prepare a short checklist for your contractor or quote form: slab thickness, drain location, site access, and your target timeline.

How Vic Sawing & Drilling approaches a recess cutting job

Recess cutting is routine work for licensed operators experienced in this field. On a typical job, the slab is scanned for reinforcement and services, a SWMS is prepared, and wet cutting or on-tool extraction is set up before the first cut goes in.

Equipment is sized to the job, whether a handheld recess disc for a single bathroom or a walk-behind saw for a larger commercial fit-out, and removal and disposal are managed so the site is left clean. If you’d like to see the techniques in practice, our page on the benefits of hiring a concrete cutting crew covers what a licensed crew adds over DIY attempts on load-bearing slabs.

Where most recess cutting advice gets it wrong

Most guides treat recess cutting as a tool selection problem: pick the right grinder, get the right blade, and the job falls into place. That’s backwards. The variable that actually determines whether a curbless shower works long-term is the sequencing of depth, slope, and waterproofing, not the hardware.

A recess cut to the wrong depth, even by a quarter inch, forces a compromise somewhere downstream: a thinner mortar bed that cracks, a membrane that gets stretched too thin at the drain, or a slope that never quite reaches code. The step-cutting discipline and the repeated dry-fitting of the drain flange matter more than which brand of diamond disc you buy.

We’d also push back on treating dust control as a site-safety afterthought tacked onto the end of the job. Under Victoria’s industry standard, it’s a planning input that shapes which tool you can even use. Readers who plan dust control and slope together, before the first cut, end up with fewer surprises than readers who plan the cut first and retrofit compliance later.

— MYBMC

Getting a quote for your recess cutting project

A fast, accurate quote starts with a few details: photos of the area, the slab thickness if you know it, the drain or fixture location, site access, and your preferred timing. Send those through and we can scope the job without a back-and-forth.

On the first visit, we scan the slab, prepare the SWMS, recommend the right dust controls for your site, and leave you with a written quote before any cutting starts.

• We confirm slab reinforcement and services before quoting, not after.
• We recommend wet cutting or on-tool extraction based on your site conditions.
• We provide a written scope and price so there are no surprises mid-job.

Request a quote through our concrete cutting services page or ask about scheduling a free site assessment if you’d like a closer look before committing.

FAQ

How do you cut a groove in concrete?

Score the groove’s perimeter with a diamond-blade saw, cutting in shallow passes rather than one deep plunge, then clean out the material with a chisel or small breaker. For deeper grooves, step cutting in passes of about 0.5 inch keeps the blade from binding or overheating.

What is poor man’s concrete?

The term usually refers to compacted gravel, crushed rock, or a simple sand-cement mix used as a low-cost substitute for a full concrete pour, often for informal paths or temporary surfaces. It isn’t a recognized structural material and isn’t suitable for load-bearing slabs or recess cutting applications.

What groove cutting depth does a concrete recess need?

For a curbless shower, plan for about 1.5 to 2 inches of depth to fit the slope, waterproofing membrane, and tile or mortar bed. Smaller grooves for conduit or drainage lines are typically cut to match the specific pipe or cable diameter plus clearance, so the depth varies by project.

What is the 4 2 1 rule for concrete?

This isn’t an established concrete standard, and we haven’t found a recognized definition tied to slab cutting or design in primary technical references. If you’ve seen it referenced for a specific application, check the original source, since definitions circulating online vary and aren’t consistent with guidance like ACI 360R-10.

Do I need a permit to cut a recess for a shower drain?

Permit requirements depend on whether the work involves relocating a drain or altering plumbing, which typically falls under your local building authority’s rules. Check with your local council or building surveyor before cutting if the drain position is changing.

Sources

• Safe concrete cutting and drilling (WorkSafe Victoria industry standard)
• Preventing exposure to crystalline silica dust | WorkSafe Victoria
• ACI 360R-10: Guide to Design of Slabs-on-Ground
• Curbless shower in existing concrete floor (ARH Foundation)
• 200mm puddle flange recess kit (The Waterproofing Shop)

Recommended

• Concrete Trench Cutting: 4 Checks Before the First Cut in Australia
• Concrete Cutting Werribee VIC 3030