What combination of latex/tile adhesive are needed in laying electric underfloor heat - TilersForums.co.uk | Tile Forums

mikehumphrey@bt · 31-01-2008

We have been given a lot of conflicting advice on laying underfloor heating and tiling. Please help! We have a floating, 22mm chipboard floor over 50mm insulation. We are going to lay 200watt heating mat, then porcelein tiles. Do we need to treat the chipboard surface? What flexible tile cement should we use? Do we need to put a layer of anything under the heating mat? Thanks for any advice or experiences of what works and lasts!

**grumpygrouter** · 31-01-2008

You should have been given installation instructions with your heating mat system. I think more cause for concern is that you are looking to tile onto a floating floor. This is not an ideal base to be tiling on because of the amount of movement that can occur.

If you are to proceed, I would suggest at the very least priming the surface with something like BAL Prime APD then fix the mats, skim over the top with a levelling compound then use BAL Single Part Flexy or similar.

Some of the longer established tilers on here will probably give you additional advise on the best way to go.

Oh, and you will need a flexible grout such as BAL Superflex wide joint grout.

Grumpy

**rob hutchinson** · 31-01-2008

I have always used a flexible levelling compound such as Arditex in addition to rapid set flexible & a flexible grouting . (Bal & Ardex) offer superb product ranges with excellent technical backing.

Leatherface · 31-01-2008

The answer is - do not tile directly onto the chipboard floor - this must be first over -boarded with plywood ( the recommended depth is 12mm, but 9mm will usually suffice)
After boarding, lay mat then self level over, then tile.
You are asking for problems if you go straight onto the chipboard

JOHNNYCLARKE · 25-02-2008

I Think Youre Heading For Big Trouble With A Floated Floor /electric Heating And Chipboard.
I Have Fixed On To Floated Floors Years Ago With Bal Fast Flex For A Friend And Never Come Back On Me.
But Add Heating And I Would Be Vary Wary.
Chipboard Is Not Very Stable And It Will Want To Flex.
If You Really Want To Do It And I Do This With All Electric Heating On Timber Substrates ,even Over Rigidly Fixed Real Quality Plywood, Prime Boards Then I Screw And Glue Wediboard Or Dukka Or Marmox Or Similar Min 12mm.
But You Should Check For Yourself With The Adhesive Manufaturer You Wish To Use If They Guarantee This On Chipboard.

This Insulation Board Not Only Acts As A Separating Membrane Between Tile And Timber But Stops Any Heat Going Down Which Means Less Heat Loss And Extra Bills To Heat Up Floor.
Ditra Can Be Used A Separating Membrane But You Have To Have A Min 5 Mm Cover On Top Before You Tile I Think And It Still Does Not Stop Heat Going Down.

Hope This Is Of Help