Basement dampness

[STUART27]

Hi Folks

Posted a topic recently entitled "Townhouse in the country" and have now moved in. I'm just getting to know the place properly and my only concern is the basement.
I believe it was "tanked" a few years ago. It has a tiled floor and plain painted walls. The whole basement area has radiators, however there is a lot of flaking paint on the walls and a definite damp smell. Having only lived in the house a few weeks, I haven't had the opportunity to see what it will be like in colder weather. Neighbours say that they have a similar problem but that it is more associated with condensation in the summer months. I don't think keeping the basement warm will be a problem as it's heated, both with central heating radiators and a large coal fire in the family room.

I'd like to tidy up the walls for now and re-paint. Can anyone suggest the best paint or other products that will help avoid flaking. Should I consider re-plastering? If so, what should I use?

Hope you can help


Stuart

 

[Midsomer Simon]

Half my house is built into a hill....some damp tends to be an inevitability. I find it is much worse during the summer months as the walls start to "sweat".

I try to keep the rooms ventilated as much as possible and accept the presence of damp....

 

[biffvernon]

It does sound like summertime condensation on a relatively cold wall. I have a wall that used to be smeared in cement and then gypsum. Every summer it would get wet, the gypsum would go all fluffy and the emulsion paint would fall off. This doesn't happen since I removed the gypsum and plastered with lime. I think what is happening now is that any moisture on humid days is absorbed by the plaster quite harmlessly and returned to the air when the rh is lower again.

 

[Lynn]

Wouldn't flaking paint suggest moisture from behind the paint through the wall? Or can condensation make paint flake? I guess I've always assumed the moisture would be from behind--then what you do to the surface is not going to help much unless the root can be solved.

 

[biffvernon]

Wouldn't flaking paint suggest moisture from behind the paint through the wall? Or can condensation make paint flake? I guess I've always assumed the moisture would be from behind--then what you do to the surface is not going to help much unless the root can be solved.

I think a lot of what people think is rising damp maybe condensation. Water from the atmosphere gets through the paint layer (yes modern emulsion paint is vapour permeable, just not nearly as much as limewash and distemper) and condenses in the gypsum where it reacts chemically causing the calcium sulphate crystals to swap between the variously hydrated states of anhydrate, hemihydrate and gypsum. These changes involve changes in crystal size causing the plaster to lose strength, become powdery and cause the paint to blister and flake off. These problems don't occur so much with lime plaster as it can absorb a lot of water without any chemical or structural changes that would weaken either the plaster itself or the plaster-paint bond.