Quartz tiles and UFH / UTH ( under tile heating )

[lakelandfolk]

WE are about to down size and have purchased a renovation project and would like to install UFH in the kitchen.  We have lived with full house, wet UFH for 20 years and worried that we will struggle to live without it when me move. It is a 1990 house with concrete floors but no insulation. We would prefer not to have to take up the existing floor and excavate to facilitate the insulation and pipe work so are looking at a low power electric system, say 100 w/m2. The total area is 20 m2 and a radiator will provide the space heating, the UFH is to provide that extra bit of comfort we become so used to.

The issue comes with the tiling, my wife is desperate to have a white sparkling Quartz tile (mirror chips in tile surface) laid in the kitchen, however the supplier says Quartz is not suitable for UFH.  I am surprised at that and would have thought the level of heat generated by a 100 w/m2 electric system would be unlikely to cause any issues with the resin in the quartz. 

 

Has anybody else considered Quartz on UFH?  What temperature would cause damage?

[Nickfromwales]

Can you lose 30mm of head height / increased floor height. I'd heartily recommend putting at least a 25mm insulation backer board over the concrete, before the tiles and adhesive. Why pay to heat a floor forever when you can pay once to insulate and reduce the discomfort of the tiles underfoot, once and for all?

Id REALLY look at negating the UTH ( under tile heating ) if at all possible. 

 

[joe90]

I remember looking at a table of max heat allowable for different floor types and top of the list (27) was wood ( I think ?)

[lakelandfolk]

Thanks Nick, that could be a plan because I could then do the same with the living/dining room floors which is to be carpeted making all of the ground floor that little bit more comfortable.

What type of board are you referring to, what make??

[lakelandfolk]

http://www.thermogroupuk.com/insulations-adhesives/econoboard/econoboard-coated-underfloor-heating-insulation-boards.html

 

Nick, Is this the type of product you suggested, comes in various thicknesses from 6 mm to 50 mm. The 20 mm specified as 1.74 w/m2k

[Nickfromwales]

Yes. The generic function is the same, just check which has the best insulation value tbh. 

Disconnecting thermally from the slab will help a lot so I'd certainly consider it as a favoured option. 

Remember the tile will still have a natural chill to it, even with the ~25mm insulation, but it'll be far better than without. 

Id still consider UTH in the room with the quartz, but go for a 50w perm2 kit so it's just a very low background heat. Another advantage of the insulation boards will be reduced heat loss, cheaper running costs, and a much faster response / recovery time ( so you can literally turn it on / off with use rather than leave it low throughout the occupied day ).

[Nickfromwales]

PS, the thicker the better. Can you squeeze 30mm in? Check with front and back / French doors which open in to the house.