Damp advice

[Stonehouse]

We have a damp cottage. It has been pointed in cement which we are removing and having it replaced with lime. We have timber floors.

We have removed some boarding inside and some of our granite walls inside are showing lots of salts (white solid). It’s very cold! We have been advised to build stud walls off the granite and tank the bottom of all our walls.

I’ve read not to tank. It has been suggested to use lime insulating plaster. But now I’m worried the salts will come through. The cement outside has made the internal lime very crumbly. We are going to insulate around our timbers.

Please can anyone advise on what to do. We have some damp against one of our internal walls which we share with neighbour. High tidal mark and smells damp.

Thank you so much!

 

[malcolm]

Makes a lot of sense to repoint the exterior with lime. For timber ground floors it's important the air vents are functional to keep them dry.

The tanking I've removed here obviously didn't work. Once the wall becomes soaking wet water still gets through the tanking, just at a slower rate. Eventually it gets into the gypsum plaster but can't get past the modern emulsion paint so spreads up the wall.

I've recently replaced some concrete render with lime inside straight onto a brick wall. Some brown stuff did came through when the plaster was drying but it seems to be clearing up so I might get away with it.

Of course it is a good idea to check for leaks when it's an inside wall that's damp. Figure out where the services go to understand where any excess water might be coming from. Though concrete and waterproof coatings will make the internal wall soaking wet and it might just be that. I've had damp and lots of salts coming out of the walls halfway up the stairs where there was no source of water other than the traditional missing damp course.

 

[Lacan07]

We have a damp cottage. It has been pointed in cement which we are removing and having it replaced with lime. We have timber floors.

We have removed some boarding inside and some of our granite walls inside are showing lots of salts (white solid). It’s very cold! We have been advised to build stud walls off the granite and tank the bottom of all our walls.

I’ve read not to tank. It has been suggested to use lime insulating plaster. But now I’m worried the salts will come through. The cement outside has made the internal lime very crumbly. We are going to insulate around our timbers.

Please can anyone advise on what to do. We have some damp against one of our internal walls which we share with neighbour. High tidal mark and smells damp.

Thank you so much!

With regard to the damp internal wall, does this wall abut any external walls? And is the floor in this area definitely timber with a sub void served by working air bricks? And as Malcom say check for any leaks in the services.

 

[Stonehouse]

Thank you both very much for your response.

Yep we have air bricks and a nice ventilation coming through them to help our timbers.

We have a chimney breast next to both walls. The chimney breast hasn’t got a lead tray. Can’t see any other issues. It definitely smells damp. We seem to have some sort of board against the walls and at the bottom it is coming away.

Malcom - would you advise against the tanking? I don’t see why we can’t just build stud walls with insulation off the granite. I don’t know why tanking was recommended.

 

[malcolm]

Tanking is never a good solution as it makes the wall soaking wet. And it's a real pain to remove after you decide dry walls might be a good idea.

It's a good point from Lacan07 that when you have a ventilated underfloor it ought to stop damp coming up the walls in the first place. If it's an unused chimney is it capped properly at the top? A good capping will keep the rain out and have an air gap to ventilate the chimney. Without ventilation the chimney tends to become damp. It's worth figuring out why you have damp and fixing it before deciding on a course of action.

Stud walls with insulation should be fine without any waterproofing. If there is a possible damp issue it's worth ventilating behind the stud walls so they can keep dry.

 

[Stonehouse]

Thank you, Malcolm

We will try to have a look at the chimney.

Are you able to help with any advice with the stud walls? Such as what the best materials are to use? Do you know how to layer the stud walls?

Thank you so much again for your time

 

[malcolm]

Designing insulation is never as fussy as they make it sound. I've never bothered about all the layres they want you to add. It would be useful to see a photo of what you have at the moment.

 

[Stonehouse]

Designing insulation is never as fussy as they make it sound. I've never bothered about all the layres they want you to add. It would be useful to see a photo of what you have at the moment.

Thank you Malcom. We’ve decided to do lime insulating plaster so to try and let it all breathe.

 

[paulc]

Thank you Malcom. We’ve decided to do lime insulating plaster so to try and let it all breathe.

A work colleague used hemp plaster in her little cottage in an attempt to boost the insulation. Judging by her comments, sh is far from impressed. I'd suggest looking at the specs and then compare with alternatives such as cork or woodfibre before committing hard earned cash.

 

[a twig]

Hemp plaster is great for dubbing out though, and being classed as an insulation product is 0% VAT