Cob wall damp advice sought

[lizben25]

We have a part-cob house (originally two cob cottages knocked together and then subsequently extended at least twice, maybe three times) and there are two patches of damp that are worrying me. One of them is on an exterior wall and I think (hope) that all we need to do there is lower the exterior ground level and possibly replace the downpipe (it may be leaking). Ventilation and heating are both poor in this small room so I could also look at improving those.

The second area of damp looks like it is rising up on what is now an interior wall between kitchen and living room, on the kitchen side (obviously it was once an external wall). I have a suspicion about this, having done some research on this forum and elsewhere, which is that the kitchen floor may be concrete underneath the tiles, and therefore pushing water to this wall. Does that sound feasible? The damp rises 30-40cm. Our neighbour, who also has a similarly extended cob house, suggested painting over with damp-proof stuff, but um... not sure about that. We are planning to completely re-do the kitchen, which would include re-tiling the floor; if so, should we budget for removing the concrete and replacing with something else? And is there a type of floor tile that would be best or is that irrelevant if the underneath is correct?

Then there's the question of how I find someone to come and look! Any ideas gratefully received (north Hampshire).

Thanks!

 

[Cubist]

The second area of damp looks like it is rising up on what is now an interior wall between kitchen and living room, on the kitchen side (obviously it was once an external wall). I have a suspicion about this, having done some research on this forum and elsewhere, which is that the kitchen floor may be concrete underneath the tiles, and therefore pushing water to this wall. Does that sound feasible?

Hi Lizben and welcome,

Yes but validate and sort out the exterior drainage before anything else.

Our neighbour, who also has a similarly extended cob house, suggested painting over with damp-proof stuff, but um... not sure about that.

Your neighbours advice, despite being well intentioned, is wrong. Do not do it.

Re the concrete, check it is concrete when you've lifted a couple of the tiles you may find its limecrete.

 

[lizben25]

Hi Lizben and welcome,

Yes but validate and sort out the exterior drainage before anything else.

Thanks - but this wall is now interior, although it was originally exterior..

 

[malcolm]

I've had an internal wall with damp and all the salts 1m up from the floor. The wall was sufficiently waterproof that the water had to travel all that way to get out behind some wallpaper on the stairs..

I think concrete floors should be workable so long as the wall finishes are breathable. For me the wall had been finished with waterproof plasters and modern emulsion paints. Scraping off a bit of plaster fixed it for me.

 

[lizben25]

I've had an internal wall with damp and all the salts 1m up from the floor. The wall was sufficiently waterproof that the water had to travel all that way to get out behind some wallpaper on the stairs..

I think concrete floors should be workable so long as the wall finishes are breathable. For me the wall had been finished with waterproof plasters and modern emulsion paints. Scraping off a bit of plaster fixed it for me.

ok, thanks; however, I am interested to note that the damp patch extends exactly as far as the 'newer' flooring in the kitchen; there is no damp on the wall where the previous-previous owners put a new kitchen floor down. Also, is limecrete pinkish in colour? Under the older floor that's what it looks like. Can't see any gaps under the newer floor to compare. Both lots of tiles will be coming up when we do the kitchen refit, so we'll be able to see then. But that won't be for a whole year.

 

[Cubist]

Thanks - but this wall is now interior, although it was originally exterior..

Yes, and perhaps therefore there was a land-drain beside that wall, that is now inside the house? If that were to be the case rain-water may be finding its way to that internal wall still.

 

[lizben25]

Yes, and perhaps therefore there was a land-drain beside that wall, that is now inside the house? If that were to be the case rain-water may be finding its way to that internal wall still.

urgh, thanks, will consider that too