Sealing Behind Natural Stone.

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Bluebells

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Is there any way to seal/waterproof behind natural stone, without using concrete blocks? My house is T/F and part of the house is to be faced with local stone (PP Condition). There is a section of the house, where roof is cut away, with very little room for same, ie., I don't have enough room to put blockwork - to seal the area - and stone on top of it.
1. Is there anything else I can use instead of the blocks?
2.What are the implications of putting the stone on with nothing behind it, stone being porous?
 
I wouldn't build stone without block behind. It's very important to protect the integrity of cavity in a TF build.

That will be nigh-on impossible just using stone. I'd block - and scud/scratchcoat - and then stone.

This is not someting to pinch pennies on............
 
You might be able to get away with using cement board - we have that instead of a block layer on the outside of our TF house. The plastering is expensive for concrete board, but as you would be putting stone on it, you wouldn't need to plaster (?probably?).

It's about 3/4 inch thick, screwed onto battens (so raising it from the frame) with a semi-permeable membrane behind the battens (if memory serves me well).
 
Thanx for replies galwaytt and yoganmayhew.

You are so right galwaytt, but cost is not the issue, space is.

Yoganmahew, the cement board may be a runner. Will consult with my blocklayer (THE best in the world - completely damp proofing obsessed!)
As a matter of interest why did you use cement board and how did it compare with blocks?
 
We were recommended it by the guy doing the timber framing (a rather mad Canadian, but a fantastic worker). It was mostly done for speed and it also allowed us to have an extra four inches on each outside wall by not having a block outside.

Having said that, the plasterers were a nightmare, but since you won't be doing that, you will save that pain!

I haven't seen blocks on a TF house, so I don't actually know how it compares! If you are in a site in a field like us, then soundproofing isn't an issue (and anyway you will have the stone facing), it has the same insulation properties as a block layer (i.e. not much! about 4 inches of rockwool equivalent, I believe), and I believe it is now certified for use in Ireland (it wasn't when we used it).

The actual board went up in about a day and a half, but the plastering took a few weeks (more to do with the plasterers and the weather than the thing itself).

HTH, Eoghan.
 
Ta very much. I think we may just have made life so much easier for my blocklayer ( and me ). He is considering it.
Appreciate the help.
 
Bluebells said:
....You are so right galwaytt, but cost is not the issue, space is.
Click to expand...

....you have me intrigued now.........how exactly is space an issue?

I have cement board (Durock) in parts of TF too. Getting the builder to use it was like pulling teeth, although the plasterers had no actual issue with it.

One comment I would make about it is that you can't tie your stone facing to it. Being only a sheet, it would not satisfy any criteria I can think of, where the outer leaf would have to be tied to it, for racking/stability. Think about it: a leaf of stone, attached to a 19mm sheet......how??
 
Picture this. It is a two storey house, but one room at the front is just one storey, and has a roof sloping back to a wall which then goes up to the main roof.There is not enough of an overhang on that roof to accommodate the block and the stone, and there is also a long narrow window in this wall. The stonemason will only have 4 inches to put his stone outside the block, and he does not want to cut every stone.
I want to use him because he has bought the stone from a building which has huge sentimental value for my family.
If I have to, I will pay him the extra cost, because as you say this is not something to mess with, but was wondering if I could find a way around it.
 
Extend the eaves of the roof, not that big a job, as that part isn't structural........
 
Sorry I should have also said that we have a problem building on top of the lower roof. An RSJ is in place to carry this block & stone but it is only allowing us minimum space for the cavity, a few drops of mortar may bridge that cavity. To be honest this is one more headache my T/F company have made for me.I haven't even got round to my dormer problems yet!!!!
I have a great builder, and we'll go with whatever he says.He has been working around the mistakes of the T/F co. for weeks and he never wants to hear the name mentioned again. He really hates the work they have done, and I am very disappointed with the work.
Thanks for your interest.
 
Is it essential to have a cavity wall if using stone (natural or reconstituted) on the outside? I'm considering building using the single leaf Poroton block but am wary of dampness coming from the outside via the stonework.
 
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