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Posted: Mon Sep 10, 2007 8:10 am
by Gregory
Hi all,

I have a question whose answer I cannot find anywhere in old posts, so if it has been answered before then please excuse me.

I've just laid a sandstone patio (Indian sandstone FWIW). It's on a dry-mix full bed, which is in turn on a 75mm+ sub-base. Looks great I think, but I have one concern. Around a couple of slabs there are damp patches that seem to be very reluctant to dry out. Photo shows pretty clearly, and though I took this this morning when it had lightly rained, they are visible when it has been dry for days. To avoid the obvious Q's, there is a fall, so the slab isn't the 'last puddle' after it rains

Image

It used to appear on another slab that was laid earlier (it took a while to finish the patio thanks to the bloody awful weather this year). That doesn't show it any more, so I was wondering if this was the ground drying out slowly through the slab (about 8 inches below the sub-base it's solid clay, so drainage is v. low), or something more 'sinister' (aka user error).

Cheers

Greg

Posted: Mon Sep 10, 2007 12:10 pm
by Rich H
Don't worry, this happens with new paving of porous stone. It's more to do with the final curing (I think) of the mix than anything else. You won't see it next year. Usually happens with the pointing joints, too, in the first year.

Posted: Mon Sep 10, 2007 12:35 pm
by Tony McC
Natural porosity of the stone. It's nowt to worry about.

Posted: Mon Sep 10, 2007 12:37 pm
by Gregory
Thanks. I did wonder since as I noted I'd seen it on other slabs, but didn't any more. And on pointing now you mention it and I think about it.

Greg