URGENT - Which sand for electric UFH and quarry tiles?

[Tom]

Hi peeps

I need some advice, please.....quickly!! My builder is going to want to put my quarry tiles down tomorrow but I'm not sure which sand he should use. He says it doesn't matter but I have electric mat UFH down underneath them. Presumably, anything with sharp bits could puncture the cabling? Which sand would you reccommend. I'm not using lime with this by the way, it'll be just sand. Thanks!

Jaqy

 

[NT]

builder's sand is fine. Its the least sharp of the sands, being dredged from the sea bed.


NT

 

[Tom]

Does all builder's sand come from the sea bed? I thought it depended on the area and that quite a lot comes from quarries. Is that wrong? Thanks.

Jaqy

 

[Gervase]

What most builders' merchants sell as 'plastering sand' is even softer (totally useless for limework, of course). The average building sand has grains from 5mm downwards, whereas plastering sand is all less than 2mm. Not that I think it would matter hugely with electric UFH, as the load will be spread.

 

[Tom]

Thanks for the replies guys. We're using building sand. I've had a good look at it and it seems quite fine and soft, so I don't think there'll be a problem. As ever, it's just good to run it by people who know better than me Thanks again.

Jaqy

 

[borischarlton]

Gervase, why do you say that plastering sand is totally useless for lime work? I have used it with lime putty on lath to replaster 26msq of ceiling with great results.
Rob

 

[Mark]

I'll guess that plaster made with the very fine sand (or sand with a fairly consistent grain size) is more likely to crack as it dries than sand with a better mix of grain sizes. I'm guessing that its about the rate of drying through the layer.

Or at least that is my experience. I'd like to hear what the experts say.

 

[Gervase]

It's the cracking issue, mainly, and also that plastering sand tends to have very round grains, which means that when you're working the plaster, too much of the fat gets dragged to the surface. The best sand looks as rough as a badger's bum in the dry state, but the variety in grain size and the jagged shapes makes for a much stronger and easier-to-work plaster.