Damp problem

[John]

Hi everyone,

In 2 out of my 3 bedrooms I have damp appearing from above the window on the ceiling spreading all the way along the length of the room and also in the other bedroom but not above the window on that wall but it is along the ceiling of the outside wall. At first I thought there may be a problem with a leak on the roof so I checked up the loft but everything is as dry as a bone. So the damp is comming from inside somehow which is puzzling me. We dont have the heating on at night and the windows are shut so could this be moisture from in the air caused by our exhaled air at night while were sleeping? If so is there anything I can do about it apart from leaving the heating on all night or leaving the windows open? Also what is the best paint to use for the ceilings especially the bathroom where condensation is common anyway?

Thanks.

[stevej]

Is it damp (like wet) or just mildew ?

Have you ruled out a leak maybe from a header tank in the attic ?

Is it worse after raining hard, if so is the gutter sound in heavy rain ?

International do a damp seal, I think Thompson's do as well. I don't have any experience of them though. It's better to try and find the solution. Such as a bathroom extractor fan perhaps

If it's mildew you need better ventilation and perhaps routine changes, like opening a window when showering & cooking. You could also invest in a dehumidifier.

HTH Steve

[Gary]

This is caused by Bad ventilation in your loft space condensation is running down the roof felt as you say it is only on the outside walls but it will be at the end of the roof slope HTH

[John]

Hi Gary,

Thanks for the reply,

If the roof felt has condensation running down it, how can it be making the inside of the ceiling damp though? I have been up the loft and the plasterboard on top of where the damp is, is dry and looks fine.

[Mike Riley]

We had exactly same problem, and like you have heating off at night etc. I noticed it occured beginning in October last year and went through till March. I went to B & Q and purchased a dehumidifier. We ran it for a couple of days and pulled out something like 60 litres of water (You can use the water in your iron / car etc, that can save a bit) and now run it when we have a shower / bath, etc. If you also dry your clothes / towels on radiators in the house it really speeds up the drying time (And cheaper to run than the tumble drier) We haven't had a problem at all so far this year and notice that in the mornings none of the windows have water streaming down them like they used to. It doesnt cost a lot to run and I have been very happy with it. Only problem is it's only efficient when windows are closed.

Regards

[keith_765]

I think the cause of the problem is cold air hitting the inner wall skin. It was general practise in the 60s to lay fibreglass on top of the ceiling up to the edge of the roof slope. Present day regs, the insulation is taken over the wall plate and meets a vertical layer on the outer skin of the inner wall to stop cold air causing condensation on the inner wall. If you can get some fibreglass over the wall plate and down to the top of the outer wall, this should cure the problem. There should be enough room to thread insulation between the underlay felt and the wall plate. It might be better to get some 50mm or 2" fibre glass bats or polystyrene sheet, they will be stiffer and should be easier to push down.

[CAS]

Firstly, hi all, I'm a newbie here...

Sounds very like what I have although mine doesn't seem quite so bad. I had no evidence of anything leaking so assumed (correctly) condensation...

Causes were entirely due to the previous owners who had a tumble drier in the kitchen... with no external vent!! (Needless to say that the cabinet housing the drier was completely rotten and had to be replaced imediately!

Anyway, I figure that the building style of my house (cavity breeze block with the inside face plastered directly on the blocks) and its location on the east coast of Scotland made it ideal for condensing atmospheric moisture!

The solution?

A bit more radical than anything seen here so far. I've completed the worst room and it involved lining the walls with Actis Tri-iso Super9 insulation, batons shot over the top then drywall screwed to the batons...

...needless to say that the room is now fantastically toasty and the walls are warm to the touch so I think that has done it!!!

Just got the rest of the house to do now... :-)

CAS