Unusual stains on painted wall

Frances63

I'm trying to ascertain the likely cause of strange stains from damp, presumably, on my paper lined (& painted) wall.

The wall butts directly up against the neighbours house, which was built much earlier. There is about a half an inch gap between them.

I have lived for 17 years at the house and never had damp before; however It has been empty for a few months whilst I've been trying to sell. The weather has been unseasonably warm so the heating hasn't been left on at all.

Could it be just condensation finding a cold spot in an unlived-in house? Rather than something external? The pattern is rather strange, i.e. some scratchy looking curved lines, perhaps the motion of the plasterer?

Frances63

I'm trying to add a photo...

Fire_Fox

When was the guttering on each house last inspected for damage and cleaned out? Ditto chimneys if any are on that side of either house.

Frances63

My neighbour is going to check out any guttering tomorrow. He has a rear roof terrace so can get to the area more easily from there. Hopefully.

Frances63

Frances63

Frances63

Sorry, can't seem to upload photos.

Frances63

My neighbour has been on the roof to have a look. Our two houses were built at different times but butt up against each other with the pinnacles of the roofs making an M shape (looking from the front).

He says the rain runs into a gully (box shaped rather than U shaped) in the middle (between us) which was zinc-lined and needs to be lead-lined. He thinks the zinc may have perished somewhat but lead would last 200 years.

I think this could be expensive.

On the other hand my 'patch' could just be a condensation spot due to a lack of air circulation with my house being empty for the last 3 or 4 months.

Wish I could tell what the actual cause is by looking.

Is there a way to tell which scenario is more likely?

MRSTITTLEMOUSE

We had this problem in our kitchen. Victorian house solid walls but no damp problems to speak of. Strange cold almost damp lines would appear when it was cold outside and warm inside.It always disappeared and never stained the wallpaper.
We decided to have it treated incase it was damp but when they started removing the plaster they found redundant pipework that led nowhere embedded an inch down in the wall.The pipework followed the mysterious markings perfectly. Removed the pipe and never had the problem again.
I'm not saying your problem could be something as simple as this but you never know.

Fire_Fox

Frances63 wrote: »

My neighbour has been on the roof to have a look. Our two houses were built at different times but butt up against each other with the pinnacles of the roofs making an M shape (looking from the front).

He says the rain runs into a gully (box shaped rather than U shaped) in the middle (between us) which was zinc-lined and needs to be lead-lined. He thinks the zinc may have perished somewhat but lead would last 200 years.

I think this could be expensive.

On the other hand my 'patch' could just be a condensation spot due to a lack of air circulation with my house being empty for the last 3 or 4 months.

Wish I could tell what the actual cause is by looking.

Is there a way to tell which scenario is more likely?

When was the guttering last inspected and cleaned out? Do you have a builder you trust, or a window cleaner with 'professional' ladders?

Is either house listed? If not there is UPVC guttering made in traditional shapes/ styles. Given you are selling you have a vested interest in doing things right, but not in doing things the most expensive way!

Given your house is unoccupied, winter is closing in, you will hopefully have a surveyor nosying about soon ... have the guttering cleaned out.

Frances63

Sorry forgot to say, the neighbour regularly cleans the gutter on that side, he has quite easy access to it from his roof terrace.

His house is listed (it's a BTM), mine isn't. I don't think this gulley can be seen from the outside though, so doubt it will matter if a UPVC sleeve can be put within it?

The neighbour is old school though, I think he's in his 80s, he will probably want lead.

I actually don't think this is causing my issue, because he was talking about the 'gulley' as he calls it, being further back where the roof level drops down. My patch on the wall is nearer than front of the house than that.

Thanks Fire Fox, good to know UPVC comes in traditional shapes, I will mention it