Damp problems in a new build?

It sounds contradictory: a brand-new home with damp problems. Yet we see it every week. Modern new builds are superbly insulated and virtually airtight — exactly what you want for the energy bill. But that same airtightness means moisture can no longer leave the house by itself.

Older houses "ventilated" themselves through gaps and seams. Not efficient, but effective against damp. In a new build those gaps no longer exist, and all moisture removal has to go through the ventilation system. If that system underperforms — or is set to level 1 because of noise — moisture builds up.

Construction moisture: the first year is critical

A new build contains thousands of litres of construction moisture at handover: in concrete, plaster and screed floors. That moisture is released gradually during the first year. Condensation on windows, a clammy feel or white deposits on walls in that first year are signs that moisture is being released faster than it is removed.

If humidity stays above 60-70%, mould almost always follows — usually first in the bathroom, bedroom or behind furniture against an outer wall. Besides damaging the home, it is above all a health risk.

The solution: balanced ventilation that does its job

Many new builds already have an HRV unit. Damp problems then usually have one of three causes: the system was never properly commissioned (too little airflow per room), the filters are saturated, or the residents turned it down because of noise.

All three can be fixed. We commission systems with a calibrated flow meter per valve, so every room gets exactly the right amount of air. Noise complaints can almost always be solved with the right settings, silencers or — for older units — replacement with a modern, whisper-quiet unit.

Does your new build have mechanical extract ventilation (type C) instead? Then upgrading to HRV is the structural solution: continuous moisture removal, fresh air in every room and heat recovery.