Hello and a damp stone cottage

[hardwicke]

Hello folks I've just joined and first want to say thank you for providing the comments and advice that I have found really helpful over the last couple of weeks.

We are buying a small Victorian rural detached cottage, sandstone built, some of it dressed, 500mm walls, slate pitched roofs and not listed.  The living areas are clad internally with plasterboard and the refurb looks 1960s or slightly later and there is a bit of damp.  There are no obvious period features or details inside.  The rough plan is to strip the insides, check all round for gypsum plaster or cement mortar (repointing, copings etc), remove that, do up the rainwater goods and then see where we are.  Assuming we then have a drying to dry building, it's then lime/hemp about 200mm thick on the walls for finish and insulation and wet underfloor heating on the concrete floor.

If I've gone off beam even on those simple steps, I'm sure one of you will put me right!  But then I have three questions about taking it forward that I would appreciate some help with.  

The concrete floor will have a damp-proof membrane over it before we do the UFH.  If the concrete is in contact with the stone walls do I need to hack it back round the edges to avoid displaced moisture wicking up or will it just dissapate because the walls will allow it to?

Do entirely internal works, such as ceilings and the replacement of an existing stud partition wall also need to be from breathable materials or will standard plasterboard and wall isulation do (I will use sheep wool for loft insulation)?

I'm not a craftsman, I need cosmetics!  Previously I've used decorators caulk quite bit, is that still OK or will it compromise my trying to get a breathing building.  If it will, what's the alternative.

Hardwicke

 

[MatthewC]

Hi Hardwicke, welcome to the forum.

Your cottage sounds really interesting - can we have some pictures please? Roughly where is it in the country? Is it listed or in a conservation area?

You don't mention anything about the exterior ground levels; you need the floor to be about 6" (at least) above the exterior ground, or else your walls and floor will never dry. I did the roof as the very first item, and got the water down to ground level in new RWG before I did anything else. You want to maximise the drying time if it's already damp.

You do mention a concrete floor - I think you mean that this already exists? If you are unwilling to dig it up and lay a brand new limecrete floor (ideal but not cheap), there is an alternative: some people have advocated digging a channel about 12-18" wide beside the wall, and simply laying a limecrete floor in that, to permit the evaporation you mention. I have no idea how well this works but perhaps someone will advise. If you simply lay a membrane on existing concrete then you will get dampness in the walls (it's probably already there) which you will be unable to eradicate.

For internal walls and the ground floor ceiling I reckon (reluctantly) you can use modern materials (depending on your approach to retention of traditional features) but I consider that you MUST use lime plaster for the upstairs ceiling (and I also used sheepswool in the loft).

I have no idea about decorator's caulk - where would you use it? If it's a modern professional's fix, I would bet that it won't allow breathing.

You can read my house story on my blog (click blue spot on right)

Matthew

 

[Zebra]

Do you know whether the concrete floor already has a damp proof membrane under it?

 

[hardwicke]

Thanks for the replies.

The cottage is in the Scottish borders and is neither listed nor in a conservation area. It is tiny, about 40sq meters internally and so 20cm of hemp/lime insulation is going to eat into that and I may have to compromise with my wife who wants a useful kitchen. Can't see the point myself, there's great chippies not far away! The ground is level and the floor looks to be about 4" above that. I have no idea whether there's a dp membrane under the concrete, I might get an idea when the plasterboard and skirting comes of as it should be lapped up the sides, but I'm guessing not. Hacking back 18" from the wall seems a lot! I was thinking 6" max!

I've used decorators caulk previously round door and window frames and on top of skirting boards, places where the two materials might move differently. I would imagine needing something similar here, it's only small quantities, often less per meter than the silicon you'd put round a bath tub.

As I indicated, there aren't really any internal features of note, the fireplace has been messed up and the windows are already UPVC. I'm not expecting to restore the building, but I don't want to ruin it structurally or spoil it's general character. The existing stud wall needs replacing, but would only butt its width against the stone wall at each end. I will have Building Control involved and, at the moment I have no idea how they might look at things.

Here a photo that shows a bit what I'm up against, plus one of the roof, which looks good enough to me (though I think some runs of guttering might be overloaded). I don't like the concrete coming right up to wall, that's going to have to be hacked back a bit.

 

[Zebra]

That concrete right up against the wall on the outside will contribute to dampness in the walls. Unfortunately with damp in walls, it's often a case of trying one thing, waiting to see if that has worked, which can be many months as walls take time to dry out (a month per inch of thickness being a general rule of thumb), then if you still have a problem, tackling it a different way.
High external ground level - higher than inside - faulty guttering, concrete paths right against the house, these should all be your first ports of call before trying anything more drastic.

 

[hardwicke]

Thanks Zebra, that's about what I'm thinking, tackle the obvious and then see the effect. Not sure I will be able to wait for many months, but at least the year has turned now.

 

[formerly known as]

I wouldn't use any opc/gypsum based materials internally, not even on 'internal' walling - this will only promote condensation.