Over existing uninsulated slab?

[msummers]

Do you have any pointers to information about installing on an existing *uninsulated* basement slab?

It seems like the ground under an uninsulated slab would be a massive heat sink and cause the system to run just about continuously, no?

I'd rather not insulate the slab from the top and lose the ceiling height, but that seems like the only viable option.

Thanks.

[Christopher]

I would highly recommend putting some type of membrane on top of your slab. Having the system directly on a slab does indeed cause a lot of heat to get lost right down into the earth.

The underlayments you will want to use are generally under 1/2", and some are even 1/8", meaning the small amount of ceiling height you'll lose is well worth the extra heat you'll keep in your floor rather than the earth.

There are quite a lot of products out there to use; here are some examples.

Custom Building Products' EasyMat
Wedi building panels
WECork's WECU
Noble Company's NobleSeal TS

Anything that is approved for a tile install on a slab would work for us.

[msummers]

Thanks, the Wedi looks promising.

That's also led me to Marmox which might work as well.

Thanks for the help.

[boris]

Old thread, I know... but I came to this page by doing some google research and it,s exactly the situation I'm in.

Live in Canada, Quebec, zone 5. We had floods this year (never happened where I live in over 60 years, I'm told). Used to have hardwood flooring, and removing it due to flooding is not something I want to live through again.

I have an uninsulated slab in the basement. My idea was to put radiant wires (electricity is cheap here), cover it with self-levelling concrete, then add a layer of Epoxy for the look and durability. Now, from the question above, I understand the need to "isolate" the wires from the existing slab with some kind of membrane. My concern with that is if there is ever another flood, wouldn't the water "seep" between the slab and the membrane ? If so, I would need to remove it to dry, which is as worse as what I lived through with the hardwood...

What are your thoughts ?

Thanks

B