Sandstone porch

Feb 27, 2011 3 Replies

I have a large quantity of sandstone that was once part of a Victorian church. For transportation it was cut into irregular blocks a cubic foot upwards in size.



I'm thinking of using some of it to build a front porch. To stay within PD it will need not to exceed 3 square metres, externally- or a semi-circle of 4' 6" diameter. It will continue an existing porch that is set back within the external wall by some 4 feet, so insufficient length isn't a problem.



However, the sandstone will rob at least a foot from the internal dimensions on each side (ie it will be a max. of 2' 6" inside), so in order to turn round in it, I think I'll need to make it of sandstone alone - ie no inner skin of any kind.



Which brings me to my question: does the team think that rain will penetrate the stone and make the porch unpleasantly damp, especially in winter?



Supplementary question - should I use lime mortar, to avoid the appearance in a few years time of an interesting cement lattice with a lot of stone-shaped holes in it?



Cheers Richard


Sandstone should be pretty impervious to water, shouldn't it?

To avoid condensation, you either need ventilation, or have it well sealed with some background heating.

9" solid walls are fine damp wise, especially with a dpc. Yes the walls can get a little damp, but not normally enough to cause any problem. (There's a big difference between damp, which is normal in any wall to some extent, and a damp problem.)

Yes. It takes a long time for that to happen, its really when the cement finally lets go after decades that it can go wrong. You can get away with adding 5% cement to the lime mix so it sets fast enough to not delay building.

NT

I think it depends on your sandstone. But around here, North Norfolk, those free-standing cement lattices are all too common, where someone has unwisely repointed in cement.

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