Im going to put Nu Heat floor mat down on an uninsulated Cement Slab. Should i put down a insulated layer over the cement before i put the mat down? And if so what product should i use for this purpose?

Unfortunately there isn't anything you can put over the slab.

A better choice is the wire cable systems from companys like Easy Heat and Flextherm. Their cable systems (by way of layout)can be configured for unheated slabs.

Ive been told about a product called Wedi-board that your suppose to be able to glue to the slab and then put your heat mat on that has anyone heard of or used it?

I haven't used it yet. Its got a different name I believe in North America. Can't remember what its called.

Woops..I guess its got the same name now.

http://www.wedi.de/home_usa/

Our local supplier here just started carrying the product, so I don't have any feedback other than it's really expensive.

As far as I can tell from the product info it will do what you want.

Yes,it's definitely better to use something like Wedi panel under the NuHeat but it's not a hard and fast rule.I've installed a few NuHeat systems directly on uninsulated slabs.The heat will still radiate into the tile consistently,just not as much as when an insulating panel is used.

hi
when installing a radiant system over an uninsulated slab your operational costs go up but it will still heat.Flextherm and easy heat9installed at 1 1/2" then 3" or flextherm at 2" over an insulated slab will be all the heat you need in the room.Custom just introduced easy mat - a antifracture/acoustic mat that also has an r value to insulate slabs.wire over mat then cover then tile- always be careful not to cut the cables when floating over.
have fun

I ended up using the wedi-board instead of cement backer-board for my shower, as i learned from the rep that it is waterproof, boy what a dream to work with compared to cement board. THis is definitely the product of the future for bathroom stalls, it is twice the price of Cement board but definitely worth it.

FWIW I used WEDI on some second floor showers a few years ago. WEDI is a great product. I bought a full pallet of it and by the time I paid shipping the sheets cost me about $21 per for 3X5's, double what Hardi costs.

I too thought WEDI would take the world by storm but the truth is I couldn't get anyone around here to give it a second look after they heard what it cost. I love the stuff and it is the only true 100% waterproof tilebacker on the market that I'm aware of. I was able to carry eight sheets at a time up the steps of this house, try doing that with cement board.

WEDI easily cuts and trims with a utility knife and you can place it on the wall and nail it with no effort.

If the cost were somehow competitive it would fly much easier.

I'm not at all in favor of placing any cement board on a concrete floor, it just presents too many new problems but in the case of WEDI I would try it. Especially as a thermal barrier under a heat system.