Damp stone wall

suziemoon

Hi, I've just bought a 1834 Cottage, the main and orginal cottage is built from Stone with a white render over the top. In one of the upstairs bedrooms the wall which faces South West on the outside has started developing mould patches behind a chest of drawers. Is it worth painting these walls with anti mould paint? Do stone walls commonly stay damper than normal walls? The wall is not exposed stone but has been plasterboarded and wall papered over.

G_M

suziemoon wrote: »

... built from Stone with a white render over the top.
good grief! Why? Get rid of the render.

In one of the upstairs bedrooms the wall which faces South West on the outside has started developing mould patches behind a chest of drawers.
Why?
Is it worth painting these walls with anti mould paint?
No. Find out where the damp is coming from and cure it. Don't just cover it up!
Do stone walls commonly stay damper than normal walls?
No
The wall is not exposed stone but has been plasterboarded and wall papered over.

What kind of pointing? If the stone wall is built with cement morter, it should not be - cement is harder than stone.

It should be a lime-based morter, which needs to breathe... so get rid of the render.

As for the damp:
* water getting behind the render?
* blocked gutter/downpipe = water flowing down external wall?
* condensation from internal use?

Trace the source of the damp.

Nobbie1967

I'm assuming solid walls, probably without a DPC, as the outside wall is SW facing it will get a fair bit of rain against the outside, so you may want to check the condition of the external finish as the rain may be penetrating through. Always best to address the root of the problem rather than mask the simptoms.

G_M

Nobbie1967 wrote: »

I'm assuming solid walls, probably without a DPC,

"one of the upstairs bedrooms the wall"

:huh:

suziemoon

The render has been on the House for so long the Council won't allow it to be removed unfortunately, our neighbour has already tried.

The back wall is exposed brick and this has no issues neither do the other walls. I'll get a builder in to check it all out. Thanks.

Davesnave

suziemoon wrote: »

The render has been on the House for so long the Council won't allow it to be removed unfortunately, our neighbour has already tried.

The back wall is exposed brick and this has no issues neither do the other walls. I'll get a builder in to check it all out. Thanks.

There's render and there's render. If it's the wrong kind, without the ability to 'breathe,' then it will tend to lock damp in.

As this is upstairs, that damp could be from a rainwater source (guttering, roof, cracks etc) or from a human one - condensation. You may be able to eliminate some of those right away, of course.

As others have said, tracing the source is most important, as is determining whether the exterior coating has a part in it.

In that context, a builder may not be good enough. You might need a RICS registered, independent damp surveyor. (That's not a contractor, who might be far from impartial!)

AlexMac

http://www.spab.org.uk/advice/technical-qas/technical-qa-1-dealing-with-inappropriate-cement-renders/

SG27

I'd say condensation due to lack of air circulation behind the chest of drawers. Move them and give a month to see if it drys. Also open windows for extra ventilation.

princeofpounds

Yes is this condensation or penetrating damp? It matters a lot for the solution.

How can the council dictate the finish on your house? Is it listed or in a conservation area?

G_M

princeofpounds wrote: »

Yes is this condensation or penetrating damp? It matters a lot for the solution.

How can the council dictate the finish on your house? Is it listed or in a conservation area?

or an ex council property? Leased or with restrictive covenants?

suziemoon

We are applying for planning permission to extend so the Council have said that the extension must be finished in white render the same as the rest of the property, when we asked if we could remove this they said that the property must visually remain the same. The back wall is currently not rendered and is exposed stone work which we totally love, we have tried to slip some stone into our request to extend and await their response. I have bought a dehumidfyer which is due to be delivered today so we will see how that goes - hopefully just condensation fingers crossed although it only the one wall....