Sandstone Flags and damp proof membrane

[gilest]

Hello I am new to this forum.

I have an old 17 century farm house and I wish to replace the non original quarry tiles that have been laid in the kitchen and cellar. The existing quarry tiles have been laid directly onto a loose mixture of sand, earth and chalk with no damp proof membrane. I have been recommended by most flag stone suppliers to lay a dpm but the conservation officer will not permit this as she feels that the dpm under the floor will simply drive any damp towards the walls.

Will I encounter problems if I lay either Indian Sandstone or York stone flags directly onto this damp and loose surface? I am worried about staining of the flags but presume this was how flags were traditionally laid. The conservation office has told me that I need a floor that can breath and that I should use a lime based mortar to point in the flags. Any comments?

Thanks

Giles

[84-1093879891]

I'm not sure what the best solution is to this problem, but I can't help feeling the BCO is being a bit picky. If you were to lay, say, a concrete floor and then tile it, that, in effect, would be water/damp and vapour impermeable. Would the BCO object to such a structure, and if not, why object to a dpm beneath the proposed flooring.

Anyway, as I'm not familiar with your farmhouse, I can't really say what' possible and what's not, but I can tell you about the impact of near-permanent damp on stone paving.

In effect, you're recreating an oitdoor path or patio as an internal floor, so there is no real issue with the stone, be it Indian or British, being laid on a damp-ish sub-grade, as long as it is a quality stone and the supplier vouchsafes its use in such a sitiuation.

A lime-based mortar is a good choice for stone paving, but I can't see how it would enable more 'breathing' than a standard mortar - it's just not quite as hard!

And how would the BCO react if you decide to seal the stone paving to protect it from kitchen spills and stains? Some sealants allow the paving to 'btreathe' but some don't. Does the BCO have a view on this?

It is a fact that untreated stone paving was traditionally used (without a dpm) on floors in kitchens and cellars for hundreds of years, but the practice petered out at the beginning of the last century.....just about the same time as rickets, diptheria and lots of other nasty 'traditions' petered out. Modern construction, even in older buildings, should be about finding a balance between traditional looks and current technology.

[gilest]

Dear Tony

Thanks for the advice. You may have guessed but the BCO will not permit a concrete subfloor. All in all I think they would prefer a wooden floating floor. Anyway I do not wish to upset her as we have many other issues with which she is dealing. You mention a sealant that can breath (and hopefully will not be affected if the floor is slightly damp). Can you let me know the brand/make?

I plan to lay Indian Sandstone flags on a weak mixture of sand and cement (10:1) with lime mortar pointing then sealed with a breathable sealant.

Do you think I will encounter any major problems?

Thanks

Giles

[84-1093879891]

For internal use, you could look at Golvpolish from Hagesan, who also manufacture a range of alternative stone sealants for indoors. Their products are widely available through branches of Topps Tiles.

I also came across a product a couple of weeks ago at a Trade Exhibition - LTP Mattstone. They have a website or you can call them on 01823 666213 and they'll send you more info.

[Tony Huntbach]

Hello

The best sealant we have found for the Indian stones is Lithofin Stain Stop . Can be bought online at www.extensive.co.uk . This is a top quality sealing product and there is a method statement online to help as well

[84-1093879891]

Have you used that one on your products, Tony? A bloke emailed me to say he found Lithofin just wouldn't 'take' on his Indian sandstone and ended up giving a 'patchy' or mottled look.

Obviously, this could be down to the way he prepared the flags or applied the jollop itself, but, judging from the photie he sent me, it didn't look all that impressive! :(