Weird Damp Problem

[gkular]

Hi all
I've got a single block wall that is rendered from the outside. French doors are fixed into this wall and sealed from both sides. The outside has also been painted with some weathersheild paint. The roof is polycarbonate and where it meets the wall, this is also sealed. Since its been raining recently I seem to be getting in loads of damp on the inside of the wall particulary around the door frame and roof. The blocks are very wet, although there isnt a water leak as such. I dont understand why this is happening as the wall is rendered and painting from the outside. The door is 100% sealed around all the edges. See the pictures , cam someone tell me why I am getting this damp and how I could resolve?

Roof

• gkular
• 26 Dec 2012
• 1

Outside

• gkular
• 26 Dec 2012
• 1

inside

• gkular
• 26 Dec 2012
• 1

[/img]

 

[JohnD]

looks to me like rainwater is blowing off the edge of the roof onto the wall.

Stand outside on a rainy day with a torch.

photo the roof edge detail please. Try to make the pictures upright.

edit
looking at it again, I think you need a better upstand and flashing on the wall where it meets the roof. Rainwater will easily splash up by 150mm.

I can't make out how it's been done.

It is more usual to have the roofing overhanging the top of the wall, which is much more rainproof.

 

[catlad]

Is that flash band that has been used against the wall and roof.

 

[gkular]

Thanks for your replies. I will take a couple of pictures and repost.
Yes it is a black long piece of tape thing and that is secured to the wall and roof. I checked it and it is pretty firmly in place. It isnt very wide though so I dont know how much difference that makes. Would you recommend I get a wider one? Also what is an upstand?
Thanks!

 

[JohnD]

An upstand is something that goes vertically up from the roof (in this caser) up the wall to prevent water getting into the joint, and to some extent, preventing water splashing off the roof and soaking the wall. It looks as if the wall has been rendered but not painted on the roof side so it will be very absorbent.

If you look at the catalogues of some plastic roofing suppliers they will have some examples. On mine I have an "F" section that fits on the edge of the roofing sheet, but it will be difficult to fit that now that the wall has been built, unless you take out the end piece of sheeting (which you might need to do to get a proper detail.

 

[Nige F]

. It looks as if the wall has been rendered but not painted on the roof side so it will be very absorbent.

If .

not sure about that but I reckon it`s the copings - water ingress through the joints - debate is welcome , John

 

[JohnD]

'mmmm

can't see any block/joint patterning on the wet patch.

you could test the coping idea by taping some dpc over the top, after a few more rainy days there might be a difference. It will not stay stuck for long. but might tell you if that's where the trouble is.

looking at a previous thread I gather the wall was build after the roof. so there is probably not a good joint.

 

[Alastairreid]

Its single block, cant see how dpc will make a difference.

 

[JohnD]

DPC as an umbrella. It is the right size to flop over the coving and overlap the wall a bit, to keep rain off the top for a while to see if that's the point of penetration

 

[joinerjohn]

I do wish posters would rotate their photo's before uploading them for posting. Bloody sick of having to twist my head sideways to look at pics.

I reckon you've got a poor joint between the roof and the wall with the door in it. The upstand/seal between the wall and roof is totally inadequate.