Possible damp upstairs bay

[David Hearn]

Our 1930's semi has a bay front (single bay spanning upstairs and downstairs). The soffits extend past the bay (so its not a flat roofed bay).

When we moved in, we noticed that the wall paper around the upstairs bay was coming off. I suspected this may be due to damp. What I'm wondering is what the constuction is of upstairs bays. I assume that the downstairs one is a standard cavity wall (like the rest of the house) - but the upstairs one is a bit of an unknown for me. Other houses in the street have rendered bays, tiled bays etc - whereas the front of our house is stone clad (ewww!). I suspect though that whatever construction it is - its a single thickness - ie. no cavity and therefore possibly more susceptible to damp.

So - is there anything I can do to reduce any damp problems when re-papering? Can I paint something on to stop it (I'm just after something to stop the paper coming off as we've not noticed there being any other problems with it)?

Any advice?

Thanks

D

[Colin Swan]

I have a similar 1930's semi with a square bay and as you suspect the lower bay is a cavity wall, but the upper is a single skin. You should be able to tell for sure by looking at the thickness of the upstairs wall below the window.

Mine is rendered and apart from the plaster being cracked in the bay (it's actually pretty bad throughout that room, but not so bad it needs replacing) I don't have a damp problem. Many of the other houses in the street have had theirs tiled, which is probably the one sure way of ensuring that water can't get through, although it must add to the weight.

Although you can get interior damp-proofing treatments (or gloss paint) that stop residual dampness affecting decoration, if the source of the damp has not been fixed, then you will just seal the problem into the plaster, which could make it worse.

-- Colin Swan

[stuart noble]

SBR latex polymer is probably a more efficient sealer than gloss paint. Unless the water is entering at one specific point I reckon it can get out the way it came in, throiugh the masonry. In my case I think the mortar and plaster are acting as a wick, and lining paper is just an extension of that. Shorten the wick and, hopefully, you reduce the amount of water. Sealing the inside is always a bit of a gamble but attending to it from the outside may not be possible. I'm doing some experiments on my gable end wall at the moment so we'll see how the latex stands up to the next lot of driving rain.

[David Hearn]

"stuart noble"

[Colin Swan]

Actually that sounds quite normal - wallpaper is quite hard to press down behind radiators (I find it to be anyway), so that could explain the lifting there. In other places, perhaps it just wasn't well hung!

I would imagine that damp would show itself by staining the wallpaper and/or plaster, so you may yet be OK. A good look at the state of the outside should also give you a good idea of whether anything is getting through.

-- Colin Swan

[David Hearn]

its

Well, the 3 other walls were pretty much well stuck (there were some loose patches that looked okay until we tried stripping it and then we realised it wasn't well stuck and was probably already lifted).

The radiator was fitted after the wallpaper as the bracket was screwed through the paper. The corners of the bay (either side of the radiator) were also peeling off - so it may be that its was like the other parts of the walls that had lifted, but because its on an internal corner, it showed more easily.

I'm not 100% sure its a damp problem, but with it being a single skinned wall, I was maybe expecting it. My only concern is to make sure that the lining paper we put up before painting DOES stick well and doesn't come off. Maybe I'll try something like PVA glue or something! I remember reading about someone trying to strip off a border stuck down with PVA and it being a pain - maybe that would be less susceptible to damp once its stuck, whereas paste is turns back to goop when it gets wet, hence peeling.

Thanks again

D

[stuart noble]

Better to just lay the palm of your hand on the wall. Try it on a dry bit first and you'll soon feel the difference if it's damp. I've never found meters very reliable.

It would have a similar effect but this is because the plaster isn't sucking the paste. Nice and easy to slide the paper about and, when it dries, it's a far better bond. SBR you can get from most builders merchants but it's for sealing damp. In your case PVA would do as well and is a lot cheaper.