You are a contractor or fit-out manager who needs an opening in an existing concrete wall or slab, for a pipe, a duct, a cable or a doorway, and must choose what to hire. This guide settles core drilling vs breaking concrete by the shape of the opening. It then gives the checks that come before any cutting, the site needs of each method, and what to ask the supplier.
What are the options for making an opening in concrete?
There are three common tools. Each one suits a different kind of opening.
| Method | How it cuts | Edge it leaves |
|---|---|---|
| Core drill | A hollow, diamond-tipped bit cuts a round hole, usually with water | Clean and round, within the marked line |
| Floor saw or wall saw | A diamond blade makes straight cuts in a slab or a wall | Straight and clean |
| Demolition hammer | Impact breaks the concrete | Rough, and cracks can run past the line |
The bit diameter sets a core drill's hole size. A floor saw works on slabs and a wall saw on walls. Ask the supplier which fits your surface and access.
Which method fits round holes, rectangular openings and irregular breaking?
Start with the shape, then check the structure. The choice depends on shape, size and what the concrete is part of.
| Opening | Usual method | Why |
|---|---|---|
| Round hole for a pipe, duct or cable | Core drill | Clean hole, stays within the line, less shaking than impact |
| Rectangular opening in a slab or wall | Saw, often with corner cores | Straight cuts, clean edges |
| Irregular or heavy demolition | Demolition hammer | Impact breaks shapes a bit or blade cannot follow |
Clean corners on a rectangle. A common method is to core a hole at each corner first. Then saw straight between the holes. The cores give clean corners and stop a round blade overcutting past them.
How big is too big for a core drill? Bit sizes vary by machine and rig. For a large round hole, ask the supplier the largest diameter their rig can core, and whether sawing the outline would suit better.
A large opening may need more than one tool. For example, you might saw the outline and then break out the piece inside it. Plan the sequence with the supplier.
Tip. This guide covers openings only. For the whole site, see construction power tools and their uses.
What must you check before cutting: reinforcement, services and structure?
This step decides success. Do it before the machine arrives.
- Read the drawings. They show where beams, columns, pipes and conduits should be. They can be out of date.
- Scan the concrete. Use a scanner or ground-penetrating radar to locate reinforcement, conduits and pipes. Mark the results on the surface. A scan can miss things, so ask the scanning operator what it can and cannot detect.
- Ask about structure. Is the slab, beam, column or wall structural? If yes, the structural engineer must approve the opening and its location.
- Ask about post-tensioning. A post-tensioned slab contains stressed steel tendons. Cutting one is dangerous. Do not cut or core until the engineer confirms where they are and that the opening is acceptable.
- Isolate live services. Ask the site owner to switch off and lock off any electrical circuit or other service that could be in the cutting area.
- Tell the site owner. Confirm what they need from you before work starts, such as permits or approvals.
Never cut where an unknown service might run. If the scan is unclear, stop and ask. Do not guess.
The engineer's approval covers the demolition hammer too. A method that looks gentler does not replace it.
A diamond bit can usually cut through reinforcement bar, but slowly, and the bit wears faster. So the scan affects the time the job takes. It can also change where you put the hole.
Tip. A new doorway in a wall may need temporary support while it is cut and a lintel (a beam over the opening) afterwards. Ask the structural engineer to say what support is needed before you start.
Watch out. If a bit hits steel you did not expect, stop. In a structural element, cutting a bar needs the engineer's approval first.
What does core drilling need on site: power, water and a firm fixing?
Power. Ask the supplier what the machine needs. If the site has no suitable supply, a generator may be needed. Wet work with mains power is a shock hazard, so ask what earth-leakage (RCD) protection the machine has. See how to size a generator in kVA and kW.
Water. Wet coring uses water to cool the bit and control dust. You need a supply of water. You also need a way to collect and clear the slurry, the muddy water that comes out of the hole. Ask the site owner where slurry may be cleared, and do not let it run into drains unless it is allowed.
A firm fixing. The drill is usually held steady on a rig or stand. The rig is fixed to the concrete with an anchor or a vacuum base. A drill that moves jams the bit. An anchor means drilling into the concrete too, so scan that spot as well. In a post-tensioned slab, do not drill anchor holes either until the engineer has confirmed where the tendons are. Ask the supplier whether a vacuum base is suitable for your surface.
Ask the supplier these questions:
- Which bit diameters come with the machine, and can you hire other sizes?
- Is the rig fixed by anchor or vacuum base, and does it suit your surface?
- What power does it need, and what water supply?
- Are the bit and the stand included in the hire?
- Is a trained operator included, or do you hire the machine only?
- What earth-leakage (RCD) protection does the machine have for wet work?
How do dust, noise, vibration and slurry compare?
| Core drill | Saw | Demolition hammer | |
|---|---|---|---|
| Dust | Low when used wet | Low when used wet | High unless controlled |
| Slurry | Yes, when wet | Yes, when wet | No |
| Vibration to the structure | Lower | Lower | Higher |
| Noise | Usually lower than breaking; depends on the machine and the bit | Usually lower than breaking; depends on the machine and the blade | Usually loud |
Cutting or breaking concrete makes fine silica dust. It is harmful to breathe. Use water or extraction. Wear a respirator suitable for the dust and hearing protection, and ask the site safety officer which type is right.
Plan where slurry goes before you start, so it does not run into other work or onto people below.
How do you plan the work: marking, sequence and what is below the slab?
- Mark the opening clearly after the scan. Keep the scan marks visible.
- Fix the sequence. For a rectangle: corner cores, then saw cuts, then removal.
- Plan how to lift out the cut piece. A cut-out block can be heavy: for example, a block 1 m by 1 m and 200 mm thick weighs roughly half a tonne. Decide how it will be supported and removed before it is cut loose.
- Look below and behind. Before a hole goes through a slab, check what is under it. Keep that area clear of people and materials. A core can drop through when the bit breaks through. Plan to catch or support it, or to keep the area below clear.
- Set a keep-out zone around the work for dust, noise and falling pieces.
For a bigger job with many openings, or a whole structure to take down, see demolition project steps and equipment in sequence. If the breaking is heavy enough for a machine-mounted breaker, see excavator attachments: bucket, breaker, auger and hitch.
How to do this on Maedah
Post one request and describe the work: how many openings, their shape and size, and whether the concrete is a wall or a slab. State whether the site has power and water. Add the city, the site on the map and the dates.
Suppliers who offer floor saws, core drills or hammers in that city can send sealed quotes. Compare them side by side. Check what each one includes, such as bits, stand, operator or water set-up.
