What this price includes — and what it does not
This is the core drilling subcontractor's cost. It is one line in a hydraulic estimate, not the whole penetration package.
Included
- Core drilling subcontractor cost
- Extra-over for working at heights, if you selected it
- Extra-over for hand-held core drilling
- Minimum charge of $350 where the job falls below it
Excluded
- Your markup as the plumber
- Preliminaries, site establishment and GST
- Fire collars, wraps, mastic and make-good
- Scanning, penetration permits and engineer sign-off
- After-hours, weekend and regional loadings
Assumptions the price rests on
- Water and power are available on site.
- Metro area, weekday work.
- Minimum charge of $350 applies. The driller still has to turn up, whether it is one hole or forty.
- Standard reinforced concrete. Post-tensioned slabs need scanning and a different conversation.
- Cores above 700 mm are outside our rate data and are flagged as extrapolated. Call us for those.
How to use it
Count your fixtures off the hydraulic drawings and type them in. Each fixture gets the core it needs — a WC and a floor waste take DN100, a basin takes DN40, and showers, sinks, tubs and troughs take DN50. You do not need to work the sizes out yourself, and you will see them in the schedule once you enter a quantity.
Floor wastes fill in automatically from your basins and showers, which is the usual pattern in an apartment bathroom. If your drawings say something different, type over it.
Then add your risers. Stacks, vents, hydrant and cold water risers all pass through the slab and all get cored, and they are the line most people forget. Enter any diameter — the calculator is not limited to a fixed list. Switch to the Wall tab for anything crossing a wall rather than a floor.
Also free: our bedding and spoil calculator for trench quantities, and the rest of our estimating tools. If you would rather we just priced the whole hydraulic package, that is what we do.
Common questions
How do you price a core hole?
Core drilling is priced on diameter and depth. A bigger core costs more per millimetre of depth than a small one, and a thicker slab means more millimetres. Drillers then add extra-overs: one for working above ground floor, one for hand-held drilling where a rig cannot be stand-mounted.
On top of that sits a minimum charge, because the driller travels, sets up, connects water and power and cleans up whether they cut one hole or forty.
How many core holes are in my job?
One per fixture that drops through the slab, plus one per riser. A typical apartment bathroom is a WC, a basin, a shower and a floor waste — four holes for one bathroom. Ten apartments becomes sixty holes once you add the kitchen sink and the second floor waste.
That is why core holes catch people out. They feel like a small item until you count them.
How much should I allow for core holes?
Put your fixture counts into the calculator above and you will have a number in about thirty seconds. Whatever it gives you, remember it is the subcontractor's cost. Your own margin goes on top.
Why is there a minimum charge?
Because a driller cannot profitably attend site for one hole. Travel, set-up, water and power connection, dust control and clean-up cost the same whether the job is one core or twenty. Most metro drillers will not get out of the van for less than about $350 on a weekday.
If your calculated total comes in under that, the calculator lifts it to the minimum and tells you it has done so.
Does the price include fire collars?
No. Coring the hole and fire-stopping it are two different trades and two different line items. Every penetration through a fire-rated slab or wall must be made good to the tested system — collars, wraps or mastic depending on the pipe.
We cover what goes where in our guide to fire-rated penetrations.
What size core hole does each fixture need?
DN100 for a WC and a floor waste. DN40 for a basin. DN50 for a shower, sink, laundry tub, bathtub or trough. The calculator applies those automatically.
Risers and wall penetrations can be any diameter you type in.
Can I tender off this number?
No. It is a benchmark for sanity-checking your own allowance, not a quotation. It does not know your site, your access, your programme or what your driller will actually charge you.
If you want a number you can put your name to, send us the drawings and we will price the hydraulic package properly.
