Damp!

[Steve]

I have a large patch of damp, with smaller patches of damp around it, on the back wall of my house. I cant work out why!

Looking outside at the roof and gutters, everything seems in order. The gutter has a noticeable slope to the downpipe at the other side of the house. The roof tiles all look fine, none have slipped and all are in nice straight rows. There is an overflow pipe coming through the fascia, but nothing is overflowing (or leaking, I was up there checking the other day). The roof overhangs the wall by about 10 inches. The gutters and fascias are all new.

The only thing I can think of is that because this wall is north east facing, it rarely gets any sunshine and therefore is pretty cold, and moisture is condensing on it. The damp patch is right up near the ceiling (where the ceiling slopes into the room with the angle of the roof), about 2 feet across and 2 feet down. But the whole wall has patches of damp, especially where furniture is against it. The ceiling is dry. There is insulation in the loft, but not where the ceiling slopes at the edges of the roof - I cant get in there!!

Any ideas? I was thinking of relocating the radiator in this room to this wall if it is the "cold wall syndrome", but didnt want to just mask a problem. The walls are solid 9 inch walls.

Something that I did notice on the roof is that there is very little flashing around the chimney**, which goes through the top of the roof. Could this cause damp on the outside walls? Under the roof tiles is roofing felt, so this could conduct any water to the outside walls, but I figure the felt would run right to the edge of the overhang too, keeping moisture from the wall.

**The flashing was never raised up a course when thicker roof tiles were put on, so it looks like there isnt any from the ground.

 

[joe-90]

I think you'll have to check the gutter is not spilling out the back when it rains. It's not really cold enough to be condensation.

 

[Ricke21]

The joys of problem solving lol. First as joe said would be check gutter and roof. If it's filled with crap or tiles don't over hang enough, could let the water trickle out the back and down your wall.

Second, check loft space for tell tell sings of running water. Check beams from ridge down. If it has run along side a beam this will be very clear. Also check your overflow case it's joined in the wall. If you can't pull it out then put a cup of water down to see if a cup comes out.

If you find that you have no probs there then the next thing is the room. Solid walls can't handle hot and cold as good as cavity walls. Where you said about more damp around furniture this would indicate bad air flow of the room. Wich then relates to condensation and damp. (cure) Have a type of trickle vent in the room. Don't put stuff against wall let air flow. Also get a humidifier. Very cheap and works wonders!!

Hope this helps

 

[joe-90]

Very good post Ricke21 - welcome aboard.

 

[Deluks]

Wait, Steve's a Yorkshireman.

Have you put the heating on yet, or are you waiting til the front door is frozen shut?

 

[joe-90]

I haven't had mine on yet. CH makes you soft.

 

[Ricke21]

Thanks joe. It's a pleasure to use my skills and knowledge to help others

 

[Steve]

Thanks Ricke. A few observations:

The roof overhangs by at least 10 inches. Even if the gutters were spilling back, I dont think they'd reach the wall.

I will recheck the route of the overflow pipe.

The door to this room is always open and is heated. The thermostat is in this room, set at 21. I will start leaving the window open on the catch to get a little bit of air flowing through.