Damp problem in old stone walls in holiday cottage.

lesaurus

I have a 200 year old stone property I am slowly renovating that is used as a holiday home a couple of times a year and the walls have rising damp.

Some of the walls are completely exposed back to the stone, others have the old lime render/plaster and are stained with the damp.

These are the original walls and have no cement render/modern building materials causing the damp. All the gutters and drainage are good and am pretty sure it's not down to water ingress.

The floors are concrete, one was there before we got the place and the other we had put down with a plastic DPM. This is probably adding to the situation by forcing moisture that perhaps once evaporated through the floor towards the walls. Not sure about the floor that was already there. Can't really do anything about them now anyhow.

Most of the advice I've read is saying that the property needs heated and ventilated and the walls will slowly dry out. Trouble is we are only there for probably 3 weeks a year so this is not an option.

Some of the walls I think we can live with but there is one which is particularly bad. My idea is to build a false stud wall that stands alone in front of this wall, made from timber/metal studs, insulated with glass fibre and then plasterboarded with MR foil-backed boards.

This hopefully would create a dry, warm wall. I am just worried about what will happen to the stone wall behind with the new lack of any ventilation an heat from the house, will this just push the problem elsewhere?

Should I build the wall or render over with new lime plaster/breathable paint and hope for the best? Appreciate your comments/advice:think:

FreeBear

lesaurus wrote: »

The floors are concrete, one was there before we got the place and the other we had put down with a plastic DPM. This is probably adding to the situation by forcing moisture that perhaps once evaporated through the floor towards the walls. Not sure about the floor that was already there. Can't really do anything about them now anyhow.

One thing you could try that might help alleviate the problem - Remove a 12"-18" strip of concrete from around the edge of all the floors. Dig down so that you are below the level of the hardcore, but not below the level of the foundations. Back fill with foamed glass and finish off with limecrete about 6" depth.

Building an insulated stud wall is just going to hide the problem - The wall will never get warm from heating the building and it is quite possible that you'll get water pooling in the gap. Ventilating the gap to the outside top and bottom would help. In the long run, any timber used to construct the stud wall will get damp and rot away. If you use metal studs, these will give you cold bridges on the wall and damp strips on the plasterboard.

lesaurus

Freebear: That's a good idea about creating a breathable strip around the edge of the floor, never thought of that. I do wonder how much the floor is contributing to the problem though, my personal thoughts are that its lack of anyone living there and heating the place contributing the most - who knows though?

Regarding the cold bridging, I would build the new wall standing completely separate from the old stone wall so they wouldn't touch to any significant degree, only maybe some ties. I would definitely allow for some air circulation/ventilation.

As far as the pooling of moisture goes, it's a good point. Maybe removing the floor/DPM from between the stone wall and where the new wall is positioned would allow the moisture somewhere else to go and avoid this.

Thanks for your reply it's given me some ideas!

FreeBear

lesaurus wrote: »

Regarding the cold bridging, I would build the new wall standing completely separate from the old stone wall so they wouldn't touch to any significant degree, only maybe some ties. I would definitely allow for some air circulation/ventilation.

Cold bridging - One side of the stud work will always be cold as the side closest to the external wall is unheated. The studs do not have to be in contact with the stone wall to be subjected to cold bridging.