The Brew Cabin

Hi Guys,
Superb site, but then you knew that already!

I am in a complete dilemma over what method is ok to fix york flags (upto 5'x2'x1.5") varying thicknesses onto a concrete floor in my kitchen which will have electric Under floor heating. The issue is, some people (firms) say use only a flexible thick set tile adhesive, such as Dunlop's, but at around £15/20Kg bag accomodating 6mm UFH cable plus ,say, 25mm of varying thickness flags makes the process crazy money, even on this modest 8sq M kitchen.

Alternatively, I could use a 6:1 mortar mix, but am worried either the heating cable will create too much expansion and separate from the flags.

Your valued opinion would be much appreciated as I feel totally confused.
Gareth

This topic came up regularly a couple of years ago (it's buried somewhere in the Archive) so when I was at one of the Trade Shows last year, I asked a few UFH suppliers, manufacturers and installers for their insight and advice, which was that, for most residential jobs, a basic mortar, say 4:1 or 6:1 would be fine. Thinset fixatives are all well and good when the paving or flooring units are of a regular thickness (or thinness, if you prefer), but much of the imported stone sold as suitable for internal use comes in a range of thicknesses from 18-40mm, and so, apparently, it's better that they are all laid onto the same type of bedding.

As to whether the mortar bedding should be a wet-mix or a semi-dry, opinion was divided equally (more or less) between wet mix, semi-dry and no diff.

Tony,

I was hoping for the reply you gave, many thanks.
I guess these things are so subjective.

Many thanks once again.
Gareth