My house is only twenty years old, why is there mould?

Modern houses are sealed tightly, so the moisture a household produces stays indoors unless ventilation removes it. Effective extraction or a PIV unit is the answer, not damp proofing.

The damp is where my extension meets the old house.

That junction is a classic weak point: a missing cavity tray, a floor membrane not lapped to the wall damp proof course, or ground levels raised by new paving. Each has a specific repair.

Can I claim on the builder's warranty?

If the cause is a construction defect and the warranty is still in force, it is worth pursuing. A written survey identifying the defect is what supports the claim.

Damp proofing in Ingleby Barwick

Condensation control, mould treatment, damp surveys and penetrating damp repairs across Ingleby Barwick TS17, where modern, well-sealed estate housing on heavy clay produces ventilation problems far more often than any traditional damp defect.

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New houses get damp too, just differently

Ingleby Barwick was built almost entirely from the 1980s onwards, and its housing has working damp proof courses, insulated cavities and sealed double-glazed units. What it does not always have is enough ventilation for the way families actually live. Airtightness improved faster than ventilation design did, so moisture from showers, cooking, washing and drying stays in the house. The result is black spot mould on cool external corners, in en-suites with weak extraction, and on the reveals of bedroom windows.

Extraction that never worked

The single most common finding in a modern estate house is an extractor fan that is nominally present and practically useless: ducted in flexible pipe with sags that hold water, running through a cold loft without insulation, terminating at a grille with a stiff flap, or wired to the light so it runs for three minutes. Replacing it with a humidity-sensing or continuous-running unit in insulated rigid duct, taking the shortest route outside, usually resolves a mould problem outright.

Clay ground and later additions

The estate sits on heavy boulder clay that holds surface water. Where garages have been converted or extensions added, the junction between old and new is where damp appears: a floor slab laid without a damp proof membrane properly lapped to the wall damp proof course, an external ground level raised by a new patio, or a cavity tray missing above the new opening. Those are construction defects with specific fixes, not candidates for injection.

New build warranties

On the newer phases, a structural warranty may still be running. Where damp results from a defect in construction rather than from ventilation habits, that is worth pursuing before paying for remedial work privately, and a written survey report is what makes the case.

Prices in Ingleby Barwick

Extractor fan upgrades £180 to £450 fitted. PIV units £600 to £1,200. Mould treatment and redecoration £500 to £900 per room. Damp surveys £150 to £350. Cavity tray and threshold defect repairs from £400.