Damp around chimney

[lurknomore]

Hi,

My mother who is based in Dublin has a problem with damp on the interior walls of her house which back on to the chimney.

She rarely lights a fire but the chimney is not blocked up. I assume damp is getting in from the flue somehow. The house is around 40 years old.

Are there any D.I.Y. solutions to this? or does anyone have any recommendations for tradespeople who could have a look at this,what sort of a tradesman would you look for anyway?

She is relucant to do anything as she has had a few bad workmen in the house in recent years. She would be happy to leave it alone but I feel it could cause more serious problems.

Thanks in advance for any help.

 

[Graftgirl]

I have the same problem with both my chimneys and have also had my fair share of cowboys in to look at the problem but noone can tell me for sure what's causing it.
My own theory now is as the chimneys look fine and are of very good structure(so I am being told my various people in the know) that water/rain coming in the chimney pot is leaking in through the chimney lining somehow.

I have done my research and found that up to 35 litres of rainwater can fall down the chimney pot in a year so it's possible that your chimney is leaking in that way, my solution for this is to cap the chimney pot(especially as the chimney is unused)
The company I am using next week to cap both my chimney pots are on the web at www.chimney.ie
Of course another possibility is that lead flashing around the chimney needs repairing but I would say capping the chimney pot is a better solution to try first as it's fairly inexpensive.
Hope this helps!

 

[smallclough]

This problem is normal for old houses. It's usually NOT damp - the plasterwork may feel damp, eprobably is - but the brickwork behind won't be. It's caused by salts which have accumulated in the wall as a result of the corrosive nature of the flue gases in the chimney. As atmospheric damp reacts with the soot (and, as you say, water getting down the chimney on occasions when the wind is right) the soot forms acids, which get into the brickwork and produce salts which migrate out of the walls, forming fluffy stuff on the surface of the plaster. All that needs to happen is to take the affected plaster off, and leave the wall to breathe - it'll form fluff, brush it off - leave it for 6 to 12 months - and then re-plaster using lime plaster - NOT a modern gypsum or waterproofing plaster, which will trap moisture and salts - and eventually blow off again - refer to sites like http://www.heritage-house.org (The Fraud of Rsing Damp) or http://www.konrad-fischer-info.de/2auffen.htm to get some more ideas of solutions.

You're right to describe the cowboys - because that is just what most of these general builders are - they have no idea how to handle old buildings..