Brown Blotches on Exterior Wall Wallpaper in Upstairs Back Room

[Tim Harvey]

On my upstairs back room there are these brown stains/blotches on the wallpaper. These are on the exterior wall. I've checked the brick work on the outside for the sign of any penetrative damp, but there are no signs. The blotches are mainly located on the top of the wall, as in the image, but there are some more isolated patches further down. I've checked the plaster behind the wallpaper and there appears to be slight staining of the plaster but pretty minor.

 

[foxhole]

Could be condensation , a pic of exterior might help , wide angle showing roof etc. Do you have fans in kitchen and bathroom ?

 

[JohnD]

Brown patches of damp are common on chimneybreasts, due to tar deposits, but also where there has been a water leak above, especially from radiator water in the expansion tank in the loft or central heating pipes but sometimes just through a ceiling after an overflowing bath. I think it might be from old wood dust or builders dirt.

A leak from above may run on or behind the wallpaper. If behind, the wallpaper will often peel off as the paste is washed away.

Condensation and clean water stains are usually black from mould.

 

[Tim Harvey]

There is no sign of any water leak from the loft above (and don't have a F&E tank any more - long gone replaced by a Combi) and I'm pretty sure its not condensation based. Any remedies?

 

[bobasd]

thats not condensation it penetrating damp.
as above, it would help to have a photo of the outside at roof line or guttering.
stand back in the room and take a pic of that whole wall.
have you examined the wall in the loft?

 

[Tim Harvey]

@bobasd I've checked on the external and there are no signs of any damp coming through whatsoever (see photos - area in red box). I've checked the wall in the loft and no issues there. Somebody mentioned above about builders dirt. Well the loft is full of masonry dust - so could this be the cause? Also see photo of the whole wall.

 

[bobasd]

then i dont know what the cause could be?
do you have any furniture tight against that wall - if so then look behind to see if there is any mould.
doubtful because you mention "brown stains". condensation is typically black and spotted.

just a perhaps maybe suggestion is:
maybe the plastic verge corner of the roof above the gutter, where the felt should be dropping into the gutter, isn't working properly or is missing. you would need someone up a ladder moving tiles(?) to have a look.

 

[^woody^]

That pattern is not indicative of water staining. But what it does look like is mould/paste staining - mould feeding off the paper paste residue left on the surface.

 

[footprints]

Surprised if it is penetrating damp that is a cavity wall even if it has been stuffed with cavity insulation the usual pattern would be regular at the wall ties position.

Is the bedroom in use? Is a window left open at night? Is the house shut up tight early in the morning and everyone goes out for the day?

Thermal wallpaper may help, or of course a dehumidifier.

 

[JohnD]

the water stain is in the top, worst in the left corner (the other blotches are wallpaper pattern showing through)

I don't doubt it's a leak.

If no plumbing up there, it'll be the roof. Roof leaks can run down the timbers on show on ceiling far from the original hole. You'll need a good torch in the loft. Luckily it's raining again today.

look for any slipped tiles (binoculars will help).

p.s.

I see now the roof verge looks quite new, but I do not have experience of it. Can you show the tiled surface?

Maybe strip off the wallpaper and see if the stains are old or still growing.