StructuralEngineer.ie's short answer: fine cracks in a new build house during the first year or two are usually normal drying shrinkage of blockwork, plaster and timber, and they're cosmetic. Cracks wider than about 5 mm, stepped through blockwork, growing, or cracks at floor level with doors starting to stick are not normal. Report them to the builder and your structural warranty provider promptly.
What’s normal in a new house
- Hairline cracks at wall and ceiling junctions
- Fine vertical cracks at window and door corners
- Cracks where plasterboard meets blockwork
- Small gaps opening at skirtings and architraves as timber dries
- Cracks that appear in the first heating season and stop
These are shrinkage and thermal movement. Most builders fill them at an agreed point, often after the first year.
What isn’t normal
- Cracks wider than about 5 mm (BRE Digest 251 category 3 or above)
- Stepped or diagonal cracks through blockwork, especially tapering ones
- Cracks between the house and an attached garage or extension that keep opening
- Floors lifting or cracking, and cracks at the base of internal walls, which is a pyrite sign in some areas
- Doors and windows that start to bind after fitting fine
Who to contact
- The builder. Report in writing with dated photos and measurements. The builder is responsible for defects under your purchase contract.
- Your structural warranty provider, such as HomeBond or Premier Guarantee, if the builder doesn’t respond or the defect is structural. Warranty terms and time limits vary, so read yours.
- An independent engineer if you need to know whether the cracking is structural before you push the claim.
How an engineer helps
An independent crack report records widths, pattern, location and likely cause. That’s the evidence a builder or warranty provider needs to act, and it tells you early whether you’re dealing with shrinkage or something structural.
Bottom line
Hairline cracks in year one are expected. Wide, stepped, growing or floor-level cracks are not. Report them in writing with evidence. For an independent fixed-fee crack inspection, call 01 270 9764.
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Frequently asked questions
How long do shrinkage cracks keep appearing in a new house?
Mostly in the first one to two heating seasons, as blockwork, plaster and timber dry out. After that, new cracking is more likely to have another cause.
Should I fill new-build cracks myself?
Fine shrinkage cracks can be filled at the first redecoration. Leave anything wider, stepped or growing alone until it's been looked at. Filling it hides the evidence the builder or warranty provider will need.
Does my home insurance cover new-build cracks?
Usually not for defects or normal settlement. Structural defects in a new home are a matter for the builder and any structural warranty first.
Sources
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