Free checklist
12 Checks Before Your Slab Is Poured
Once the concrete goes down, none of this can be inspected again. Print this, take it to site, and go through it before the pour.
You do not need to be a builder to use this list. You need to be there, and you need to ask. A contractor doing the work properly will have no problem answering any of these — and one who reacts badly to being asked has told you something important.
01Before anything is dug
The setting-out is square and matches the approved plan
Every wall, door and roof sheet after this inherits the error. A stand set out 40mm out of square is still 40mm out of square at roof level.
You have seen the approved plan on site, not just at the office
Work gets built from memory more often than anyone admits. The drawing should be on site, and it should be the current revision.
02The trench
Foundation depth reaches firm ground, not just the depth on the drawing
Drawings assume soil conditions. If the ground on your stand is soft, black cotton or filled, the depth has to change — and that is a decision, not an accident.
The trench bottom is clean, level and compacted
Loose spoil left in the bottom compresses under load. Settlement cracks that appear two years later usually started here.
The trench has not stood open and filled with water
Softened trench bottoms have to be cut back to firm ground. Pouring on top of mud is the cheapest possible short-term decision and the most expensive long-term one.
03Steel and reinforcement
Bar diameter and spacing match the drawing — count it yourself
Thinner bar or wider spacing is invisible once poured and saves the contractor real money. Count the bars in a metre and check the size stamped on them.
Laps are long enough where bars join
A short lap means the reinforcement is not continuous — the slab has a weak line straight through it exactly where you cannot see.
Cover blocks or spacers are actually in place
Steel resting on the ground rusts, expands and cracks the concrete from the inside. Bars must sit within the concrete, not on the bottom of it.
Mesh is tied, not just laid
Untied mesh moves the moment anyone walks on it during the pour, and ends up in the wrong part of the slab.
04Under the slab
Damp proof membrane is down, lapped and not torn
Punctured or missing DPM is the reason floors stay damp and skirtings lift. It costs almost nothing now and is unfixable later.
Plumbing and electrical conduit are in before the pour
Anything forgotten gets chased out of finished concrete later — noisy, expensive, and weakening exactly where you least want it.
05The pour itself
You know the concrete mix, and it matches what was quoted
Mix strength is the easiest thing on a site to quietly downgrade and the hardest to detect afterwards without coring the slab.
Photographs are taken of everything above, before it is covered
This is the whole point. Once the pour starts, the only record of what went in is the record you made.
If something on this list is wrong
Stop the pour. It is the single cheapest decision available to you at that moment. Concrete that goes down over a problem does not remove the problem — it just puts it somewhere you can no longer reach.
If you want a second pair of eyes on your site before the pour, we do stage inspections on builds we are not contracted for.
Book a site inspectionWant us to check it instead?
We inspect builds we are not contracted for — foundations, reinforcement, ring beams — and tell you plainly what we find.