Damp on chimney walls

2hand pete · Post by **2hand pete** » Tue Nov 17, 2009 7:11 pm

hi all, can anyone help please. We have damp problems on the bedroom walls where the chimney's are, It's a detatched house with the chimney breasts at either end and are both external, ie flat walls inside. None of the flues are in use and are all capped off. I've read several posts about having a ventilation flow through the chimney flues, although this may cure the problem I'm thinking of re-roofing the house soon, and possibly taking the chimney stacks down to roof level and tiling over them, If I filled the flues with insulation (rockwool or similar) to my way of thinking this would prevent the warm air internally condensating on the cold chimney walls. Has anyone done this or is it a bad idea ?. The house is about 60 yrs old and has cavity walls which have been insulated, where the chimneys are its only one skin of bricks between the internal wall and the flue. Thanks for any help

Post by **ultimatehandyman** » Tue Nov 17, 2009 9:09 pm

It sounds like a good idea, but I'm not certain if it would be ok or not. It might be a good idea to ring the local building control officer and see what he says

Big Bear · Post by **Big Bear** » Tue Nov 17, 2009 9:30 pm

IME, I've recently had my new (old) house damp proof injected, while doing this they put a membrane up to 4ft around the chimney breasts, they used the polythene with hessian cover that you use for tanking cellars etc.
The company said that 1, the sulphar is coming out of the brickwork & into the plaster (the house is 112 years old). Also, 2, the chimneys are not currently in use so will form condensation, again affecting the plaster.
I'm not going to use 1 of the chimneys so am capping it at the bottom, but, putting in a vent, leaving the top open thus circulating the air.
The other will be having a wood burner fitted.

Hope this may help.

Martin.

leebwk · Post by **leebwk** » Wed Nov 18, 2009 8:16 am

Hi,

If you are considering re-roofing then it would be a good idea to remove the chimneys and tile over the top but i would incorporate air bricks at the top of the stack and at the bottom to create an air flow and keep it dry.
Do not put insulation down it as this could make the problem worse.
Although a bit extreme re-opening the flue and using it again with a stove or open fire would probably eradicate the problem altogether plus cut down your heating bills