You've been in the house a matter of months, sometimes barely one winter, and fine cracks have started appearing along the tops of walls, around door frames and window openings, often following straight lines rather than a random pattern.
This is one of the most predictable snags in a new-build, and in the large majority of cases it's shrinkage rather than anything structural. But 'usually fine' isn't the same as 'always fine', so it's worth understanding what you're looking at before assuming the best.
What's actually happening in the fabric
A new building contains a lot of moisture that wasn't there when it was designed: wet plaster, wet screed, and timber that was cut and installed before it fully dried to the moisture level it will eventually settle at inside a heated home.
As the heating runs through the first winters, all of that moisture leaves the building at once, and every material that dries out shrinks slightly. Where two different materials meet — plasterboard and timber, for instance — that shrinkage shows up as a crack along the joint.
Distinguishing the symptom from the cause
The crack you see is the visible result of moisture leaving the fabric. It is not, by itself, evidence of a structural issue — but a structural issue can also produce a crack, so the location and behaviour of the crack are what actually tells you which you're dealing with.
Causes, in order of likelihood
In a genuinely new build, the balance of probability strongly favours drying-related causes over anything structural.
- Construction moisture drying out of plaster, screed and blockwork over the first heating seasons
- Timber frame or timber components shrinking as they reach equilibrium moisture content
- Heating run harder than usual in the first winter, accelerating drying and shrinkage
- Taped plasterboard joints sitting directly over natural movement points, such as where a timber lintel meets blockwork
How to tell shrinkage from a structural crack
Check whether the cracks are hairline — a millimetre or less — and whether they stay that width over several months rather than steadily widening. Shrinkage cracks are typically fine and static once the first heating cycle has passed.
Look at where the cracks run. Cracks that follow the line of a plasterboard joint or the edge of a door or window opening are consistent with shrinkage. Diagonal cracks running across a wall away from any joint, or cracks that appear alongside doors sticking or floors sloping, need a different explanation.
Note how long the house has been occupied and heated. If you're within the first two heating seasons, shrinkage is the leading explanation. Cracking that starts appearing well beyond that point, or that keeps growing rather than settling, should not simply be assumed to be shrinkage.
What a snagging record should note
A useful snagging note records the crack's exact location relative to a joint or opening, its width, and the date first seen, since this is the information a warranty provider or builder will want when the claim is raised.
It's worth checking each affected area again after the first full heating season and noting whether the same cracks have stayed the same width or grown, rather than relying on a single one-off inspection carried out too early in the drying process to be conclusive.
Common questions
How long does new-build shrinkage cracking last?+
Most of it appears and settles within the first one to two heating seasons, as the building fully dries out. Cracking that continues to appear or worsen well beyond that timeframe should be looked at rather than assumed to be the same process.
Will the builder's warranty cover this?+
New-build warranties typically list shrinkage cracking as an expected, non-structural snag in the early years, so it's worth checking your specific warranty terms and raising it through the proper snagging process regardless.
Should I redecorate straight away?+
It's generally worth waiting until after the first full heating cycle before redecorating, since filling and repainting too early usually means doing it again as more shrinkage cracks appear.
Book a free snagging-style inspection
We'll check the crack pattern against genuine shrinkage indicators and flag anything that looks like it needs closer investigation.