Help mouldy bedroom wall

Kez07

I've just discovered that my spare bedroom has mildew under the window and behind a chest of drawers on the same wall. It's the first time it has happened and I want to know why. I have central heating (although the boiler has had problems - so we've just restored heating after a week with intermittent or none!). The window in that room is singled glazed sash and suffers from condensation and water pooling on the lower beading where the wood meets the glass. Could this be the problem? I've got double glazed wooden sashes to the front of the house and get no condensation. Should I replace the window with double glazing - will this stop the mildew on the walls? Any advice gratefully received!

WestonDave

My guess is that now the heating is back on, if you clean it off it will be less of a problem. It probably happened in those locations because under the single glazed window is a cold spot, and behind the drawers would be away from the warmth of whatever limited heating you had on.

Condensation will occur on cold spots simply because cold air holds less water than warm so as it cools it drops it. Warm moist air (cos you breathe out moist air, plus create it with showers, cooking etc) hitting a cold bit of wall will cause condensation which will in turn attract mildew. Behind cupboards is prone because its often hard for warm air to get in and warm it up.

We had similar problems in some places last year after we moved in due to the house being shut up with no heating on for some weeks before we bought it. Once the heating was running properly it didn't return. We've since had the walls insulated which also helps as the walls don't get as cold. It may be worth improving the window if you can - either replacing it or putting some secondary glazing over it. Keep the drawers slightly away from the wall to allow air to circulate but if the room as a whole is kept warm it should be fine down there - its only really when there is only short bursts of heating which don't allow heat to get into the gap.