New Build Cracks: Is This Normal or a Snag?

Most of the things that worry new-build owners in the first year aren’t defects at all — they’re the house drying out.

When a home is built, hundreds of litres of water go into it — in the plaster, the screed, the mortar, the brickwork. All of that has to dry out, and as it does, materials shrink and move slightly. That’s completely normal, and it’s why a brand-new home behaves differently in its first year than it ever will again.

It’s worth knowing that no two houses dry out the same way. A house built in winter (what we call a “wet build” in the trade) dries differently to one built in summer. And you’ll almost certainly be moving in while the drying-out process is still happening — so you’re living in the house as it settles.

As the house dries, you’ll most often see small cracks appear where two pieces of material meet. The usual spots are:

• Around the staircase
• Where the wall meets the ceiling
• Where the skirting meets the wall
• Around door frames
• Anywhere two materials join

Most of these are normal shrinkage and the builder won’t class them as a snag. The rule of thumb the industry uses is size: a builder generally won’t cover shrinkage cracks unless they’re excessive. As a rough guide, anything you could fit a £1 coin into is worth raising — and around the stairs, where movement is greater, the line is more like a £2 coin.

So a hairline crack at a ceiling junction? Normal — fill it and paint over it as part of normal upkeep. A crack on the stairs you can post a coin into? That’s worth reporting.

Small round bumps where a fixing has pushed back through the plaster — “nail pops” or “screw pops” — are also part of normal drying movement. One or two in a room is nothing to worry about.

But there’s a line here too: a handful in a single room suggests a problem. One or two — normal. Ten in one room — that’s worth raising.

Here’s one that catches people out. During the drying-out process, all that moisture coming out of the walls needs somewhere to go. If a room isn’t being ventilated properly, that moisture goes straight back onto the walls — and you get mould.

The first sign is usually black spots around the windows and around the sealant. It tends to show up in the rooms that get the most moisture and the least air: bathrooms, wet rooms, airing cupboards.

This usually isn’t a building defect — it’s a ventilation issue. As the house dries, those rooms need air moving through them. Use the extractor fans, crack a window, don’t dry washing on radiators in an unventilated room. Get the air moving and the black spots stop.

Gardens are genuinely difficult, and I’ll be honest: some builders are just poor with them.

Here’s the fair way to look at it. If a lawn is watered and looked after — not walked on heavily, no dogs tearing it up, no kids running on it for the first few weeks — it should grow. If you’ve done all that and it still won’t take, then it’s worth a conversation with the builder.

One thing people moving from the south of the country often don’t realise: a north-facing garden is wetter and gets less sun than a south-facing one. If you’ve moved from a sunny south-facing plot to a north-facing garden, the difference can be a surprise — and it’s not a defect, it’s an aspect.

A lot of “is this normal?” comes down to knowing what you’re buying — and being honest, not everyone does. The drying-out process, the aspect of your garden, the way a new house moves in its first year: that’s all normal.

But normal has limits. Poor workmanship isn’t normal, and neither is corner-cutting. If you see signs of either — excessive cracking, things that don’t line up, work that’s clearly rushed — that’s not drying out, that’s a snag. Report it.

If you’re not sure which side of the line something falls on, that’s exactly what David, our free AI snagging assistant, is for — and the within-tolerance guide on this site explains the official NHBC figures behind all of this.