Old Market Hall, Douglas

The mould was the symptom. The cold wall was the problem.

ThermoCork has been applied to this area in the Old Market Hall, by the rear door, to solve a damp problem. The rear door area had condensation and mould growth because it sits away from any warm moving air. That leaves it cold, and moisture condenses on it. Moisture is what mould and mildew thrive on.

Why it happens

Warm air carries moisture you cannot see. Put that air against a surface colder than it is and the moisture comes back out as water on the surface. It is the same thing that fogs a bathroom mirror, just slower and out of sight.

In a building of any size there are corners the warm air never really reaches — a rear lobby, the head of a wall above a door, a spot tucked behind the steelwork. The rest of the building warms up and these patches do not, so they end up the coldest surfaces in the room. And the coldest surface is where the water lands, every time.

Mould does not need much. It needs damp, and a surface that is wet most days gives it exactly that. Which is why washing it off never settles it. Clean it, paint over it, treat it — the wall is still the cold one, so it still condenses, and the mould is back before long.

What ThermoCork does about it

ThermoCork insulates the surface itself. Rather than sealing over damp, it takes the cold out of the face of the wall, so the surface sits nearer to the temperature of the air in the room instead of well below it. Once it is no longer the coldest thing in the room, the moisture in the air has nothing to condense on. No water on the wall, nothing for mould and mildew to live on.

That is why the thermal insulation values of ThermoCork make it the right answer to this particular problem. The area by the rear door did not need cleaning or covering up. It needed to stop being cold — and that is a job for insulation, not for paint.

If you have a patch of wall that keeps going black no matter how often you deal with it, this is very often what lies behind it. The mould is not the fault. It is just the part you can see.