Is My New-Build Wonky? Acceptable Building Tolerances
A floor that is not quite level, a wall that seems to lean. In a new home, some of that is normal and some is a defect. The difference is not a matter of opinion, it is a measurement. Here is how it is judged.
In short: a new home is hand-built, so it is never perfectly straight, and a small amount of deviation is expected. The question of whether a sloping floor or leaning wall is a defect is answered by measuring it against a published tolerance, not by eye. As a rough guide, a floor within about 4 mm per metre and a wall within about 10 mm of plumb per storey are often treated as acceptable, though the exact figures come from your warranty provider's standards, such as the current NHBC Standards. Something can be within tolerance and still annoying. It becomes a genuine concern when it exceeds the tolerance, when it is getting worse, or when it comes with cracking that suggests movement rather than finish.
Why a new home is never perfectly straight
Houses are built by hand, from materials that move. Bricks and mortar are laid by eye to fine limits but not to laboratory precision, timber and plaster shrink as they dry, and the whole structure settles a little as it takes up its weight in the first year or two. The result is that no new home is dead level and dead plumb, and it is not meant to be. The industry accepts this by setting tolerances: the amount of deviation that is considered normal for each element, beyond which it counts as a defect to be put right.
That is why the useful question is never "is it wonky", because to some tiny degree everything is. The question is "is it within tolerance", and answering it means measuring.
Defect or not: it is measured, not eyeballed
A deviation is judged with a straight-edge over a defined length, not by standing back and squinting. A wall is checked for how far it leans from vertical over a storey height. A floor is checked by laying a straight-edge across it and measuring the gap underneath. Visual finishes, such as marks on glass or paintwork, are judged from a set viewing distance in normal daylight, not with your nose against them. The diagram shows the two checks people ask about most.
What is normally accepted
The exact numbers belong to your warranty provider, and they update them, so treat the figures below as a general picture of the kind of tolerance the industry works to, not as a rulebook.
| Element | Typical tolerance (guide only) |
|---|---|
| Wall out of plumb | About 10 mm per storey, more over full height |
| Floor out of level | About 4 mm per metre |
| Wall or ceiling surface | About 5 mm under a 2 m straight-edge |
| Shrinkage cracks (plaster, junctions) | Up to about 3 mm, cosmetic |
| Doors, out of level in the frame | A few millimetres, more on wider openings |
Typical industry guidance only, in line with the kind of figures set out in the current NHBC Standards. Exact tolerances vary by warranty provider and are updated over time, and they do not apply to existing, unaltered finishes in a conversion. Always confirm against your own warranty standards, or ask a structural engineer.
When it is more than cosmetic
Tolerances deal with how well the house was finished. A separate question is whether something is structural, governed by Part A of the Building Regulations rather than a finish tolerance. A floor that is out of level because the screed was laid unevenly is a finishing issue; a floor that is dropping because a joist is undersized is a structural one, even if the measured slope is similar. The clues that push a defect from cosmetic into structural are familiar ones: the deviation is increasing, a wall is bulging rather than simply leaning, doors and windows that used to work have started to stick, or there is cracking in a pattern that suggests movement. Our guide to when cracks are structural covers those signs in detail.
What to do if you think it is a defect
Start by writing it down. Note what is wrong, where, and ideally a measurement and a photo, and put it to the developer as a snagging item. If they say it is "within tolerance", ask which standard and figure they are measuring against and how they measured it, because that turns a difference of opinion into a checkable fact. If you cannot agree, your warranty provider has a resolution process. And because the whole thing usually comes down to a measurement, an independent structural engineer's report, stating what was measured and whether it is within tolerance or a genuine defect, is often what breaks the deadlock. It is also worth getting one before you complete on a new build, so anything out of tolerance is on record from day one.
What EMA Structures does
When you are stuck between your own eyes and a developer telling you it is fine, we give you the measured, independent answer. We inspect the property, measure the walls, floors and openings you are worried about against the relevant tolerances, and set out clearly in a written report what is within tolerance, what is a genuine defect, and crucially whether anything is structural rather than cosmetic. That report is something you can put in front of the developer or the warranty provider, and it tells you honestly when something really is just the normal character of a hand-built home. This sits alongside our structural surveys for buyers.
Worried your new home is not right?
Tell us what you are seeing, with a photo and a rough measurement if you can. Send us the details and a structural engineer will tell you whether it sounds like normal tolerance or something worth measuring properly. A structural inspection with a full written report costs £495 + VAT, see our fees guide, correct as of August 2026.
New-build tolerance questions
Is it normal for a new-build floor to not be perfectly level?
A small amount of deviation is normal, because a house is hand-built from materials that settle and shrink. Floors are judged against a tolerance rather than a spirit level, and as a general guide a deviation of around 4 mm per metre, measured with a straight-edge, is often treated as acceptable. It becomes a defect when it exceeds the published tolerance for your warranty, when it is getting worse, or when it comes with other signs such as cracking or sticking doors that suggest movement rather than finish.
How much can a new-build wall lean before it is a defect?
Walls are checked for plumb, meaning how far they lean from vertical, measured over a defined height. As a rough guide, a deviation of around 10 mm over a single storey height is often within tolerance, with a larger allowance over the full height of the building. Anything beyond the published figure, or a wall that is bulging rather than simply leaning, or a lean that is increasing, should be assessed, because those can point to a structural issue rather than a finishing one.
Who decides whether a new-build defect is acceptable?
In the first instance the developer, measured against the tolerances in their warranty provider's standards, such as the current NHBC Standards. If you disagree with the developer, the warranty provider has a resolution process. Because the argument usually comes down to a measurement, an independent structural engineer's inspection and report, setting out what was measured and whether it is within tolerance or a genuine defect, is often what settles it.
Are shrinkage cracks in a new build normal?
Small shrinkage cracks are very common in the first year or two as a new home dries out and settles, particularly fine cracks in plaster, at the junctions between different materials, and above doors and windows. As a general guide, hairline cracking up to around 3 mm in these locations is usually cosmetic and can be filled and decorated. Wider cracks, cracks that keep growing, or diagonal or stepped cracks through brickwork are a different matter and are worth having looked at.
What if the builder says it is within tolerance?
Ask which standard and figure they are measuring against, and how they measured it, because tolerance is a measured question, not an opinion. If their measurement is fair and the deviation really is within the published tolerance, it is unfortunately accepted as normal, even if it is annoying. If you are not satisfied, an independent structural engineer can measure it properly and tell you whether it is within tolerance or a defect, which gives you an evidenced position to take back to the developer or the warranty provider.
Not sure if it is normal or a defect?
Send us what you are seeing and we will tell you whether it sounds like normal tolerance or something to measure properly, with a full report if it needs one.