Condensation , single skin wall

[sig1973]

Hello,

I have a bay window in an upstairs bedroom which has a single skin brick wall below the window. Rendered on the outside. I have always had a problem with damp patches and am pretty sure it is down to condensation.

After reading a few posts, would the best solution be to take off the plaster and then stick 50mm insulated plasterboard directly to the wall.

Would the plasterboard then need skimming if it is only going to have backing paper put over it?

Thanks, Si.

 

[tony1851]

You would need to be asolutely certain the damp was not penetrating damp from rain. Even though the bay is rendered small cracks may be present, letting water in.
Aside from that, as it will only be a small area, why not remove the skirting and just do it and see what happens over a few months. Don't paper it or fix skirting in the interim,and if it doesn't solve the problem, you won't have spent too much.
Condensation can be caused by inadequate heating and ventilation, particularly in bedrooms.

 

[^woody^]

"Damp patches" would suggest penetrating damp, not condensation

You can still do as proposed, but use a different fixing method and a sheet of polythene or membrane up the back of the wall

 

[sig1973]

Sorry, should have been clearer. The wall gets wet with condensation, obviously worse now than in the summer, and mould starts to grow. The outside render is in good condition. Now you have mentioned heating, I will check that the radiator is the correct size for the room, it may be a bit small.

Si.

 

[noseall]

To comply with building reg's you would be asked for 125mm of celotex type of insulation.

However in this instance adding 50mm of celotex or similar will be a big improvement on what is there already. It may or may not stop condensation issues, largely depending on occupancy lifestyle and wall exposure, i.e. N-S-E-W facing etc.

 

[JasonF]

We had the same problem caused by condensation, we improved ventalation and also covered the bay and outside wall with polstyrene wall veneer, buy it from homebase stick it on with PVA and a roller and wall paper over it. I did this over two years ago and no problems. Give it ago Its a cheep solution.

 

[sig1973]

How did you improve the ventilation please?

 

[JasonF]

When we changed the windows to plastic double glazing we had problems with condensation and mould, This forum suggested ventalation was a problem and they were right, because the old drafty windows gave good ventalation, anyhow what I did was installed an extractor fan into the bathroom and put an air vent into the living room and a couple of bedrooms and in the warmer months leave the windows up stairs open. I would try the polystyrene wall veneer from Homebase in the bay.