New-Build Condensation: Why New Homes Get Damp Too
4 August 2026 · 1 min read
It surprises a lot of new homeowners: a brand-new house can have condensation and even mould in the first year, for a reason that has nothing to do with poor building quality — the building itself is still drying out.
Why new homes are wetter than they look
Wet trades — plastering, screed floors, brickwork mortar, and concrete — all contain a significant amount of water when installed, which needs months to fully evaporate out through the surface. A typical new-build can take the best part of a year, sometimes longer for thicker elements like screed, to fully dry out, and until it does, that moisture adds to normal household humidity and increases the risk of condensation, especially in a well-sealed, well-insulated modern home with limited natural draughts to carry it away.
Signs this is what’s happening
- The property is less than around 12 months old, or has had significant replastering work done recently.
- Condensation and any associated mould appear generally, rather than being concentrated at one clear defect.
- It’s worse in the first winter and gradually improves over subsequent seasons as the building continues to dry.
What to do
- Ventilate more than you might expect to need to, particularly in the first heating season — new-build ventilation systems (often mechanical extract or MVHR) need to be used consistently, not just when it visibly steams up.
- Keep a low, consistent background heat through the drying-out period rather than heating intermittently.
- Avoid drying laundry indoors during this period if possible, since the building is already releasing extra moisture of its own.