Why the mould calls start when the heating goes on

Every winter, the damp and mould reports climb from late October and keep coming until spring. It's condensation, and it's predictable enough to plan for.

The pattern doesn't change. The clocks go back, the heating goes on, the windows stay shut... and within a few weeks the reports start climbing.

Once you understand why, it stops being a surprise every year.

Where the water comes from

An ordinary household puts up to 23 pints of water vapour into the air every day, roughly 13 litres. Here's where most of it comes from:

• Drying clothes indoors: around 9 pints
• Cooking and boiling the kettle: about 6 pints
• Breathing: around 3 pints
• Washing up, bathing and cleaning: the rest

In summer, most of that leaves through open windows. In winter, it stays in.

Why it turns into mould

Warm air holds more moisture than cold air. When warm, moist air meets a cold surface, it gives up its water.

That's why condensation forms on external walls, window reveals, the backs of wardrobes pushed against outside walls and the corners of rooms where the air doesn't move. Keep a surface damp for long enough and mould grows.

It's also why winter reports cluster in the same places every year: bedrooms and bathrooms, behind furniture and on the coldest walls.

From 30 November, excess cold becomes a hazard in its own right under Awaab's Law Phase 2, so the two are worth investigating together. A wall that's cold enough to grow mould could easily point to an excess cold hazard in the same room.

Why a leaflet isn't the answer

It's tempting to send tenants advice about opening windows and call it done. It isn't enough.

The government's guidance on damp and mould is clear that problems shouldn't be put down to tenants' lifestyle, and under Awaab's Law that position carries real risk.

Most tenants can't dry washing outside in December. They can't afford to heat rooms they aren't using, and they didn't choose where the extractor went. The building has to cope with normal life, not the other way round.

What fixes it

Condensation is a building problem, and it needs building fixes. All of these cut the moisture that settles:

• Working extractors in kitchens and bathrooms
• Background ventilation that's actually open
• Insulation that lifts the temperature of cold walls
• Heating that tenants can afford to run

Our loft and ventilation team installs whole-house ventilation, upgrades roof ventilation and insulates lofts. Our mould eradication team treats the mould and puts prevention in place.

We always survey first, because the fix for one property isn't the fix for the next.

Plan for it

Because winter demand is predictable, the landlords who cope best don't wait for it. They book capacity before the reports start and use last winter's reports to target the worst stock first.

We work with housing associations and local authorities across the social housing sector, and we're happy to talk through what your winter programme needs.

Planning for this winter's mould reports? Call us on 01924 723723, email enquiries@gmegroup.co.uk or get in touch here and we'll get back to you.