Second floor radiant heat install

Captiveshark

We have a second floor bedroom for which we are getting bids to put in electric radiant heat. Each contractor has had a different method.

Here is the situation. Temperate So Cal house, not many days of heating a year. High ceilings and this room faces north. No zones for the heating system.

We have stripped the carpet, and found 5/8 plywood in good condition. After some sanding, it is within about 1/8 inch of flat, but there is a small consistent slope. One side of the room is a half inch higher.

We have ordered electric radiant which comes in a mesh which will be hot glued or stapled before being covered. On top will be hardwood which is floated. This hardwood is specifically certified and warranted by the manufacturer for radiant.

So, here are some of the differences in approach:
1. Quickrete, thinset, or self leveling.
2. Whether we need any sealing of seams, or primer for the plywood subfloor.
3. Whether there is a moisture/vapor barrier between the plywood subfloor and the thinset, etc.
4. One contractor wanted to add backer board, but had so many layers we discarded this option.

Any suggestions? We Are looking for something which will last and won't squeak.

Lastly, I think it would be simple to do the hardwood flooring myself, rather than have a contractor do it for $500-1000.

Thanks for your help

joecaption

Why not ask the company that sold you the mat or the manufacture of the mat these questions?
Anyone here would only be able to give you there best guess, done wrong and it's a complete do over.

Daniel Holzman

Not sure what type of hardwood floor you have, but if it is traditional 3/4 inch tongue and groove, how were you planning to nail (staple) the hardwood down? You can't use nails over electric heat, was it going to be a glue job?

Captiveshark

The hardwood will be a floating install.

Captiveshark

Their install instructions are for naildown hardwood. Yes for electric. We prefer floating

joecaption

Unless it's an engineered hardwood floor I do not see it going over that heating system. I've never heard of a soild hardwood floor that floats.

Captiveshark

Lots of people are surprised, but here it is, http://www.junckers.com/?pageid=H3057 . "Thanks to the Junckers Clip System, a floating floor can be installed over the majority of modern underfloor heating systems, such as electric or piped hot water systems fitted within a screeded subfloor, which give an even heat distribution. We can even accommodate underfloor heating systems contained with battens or joists."

Their instructions say "screed" (the UK version of screed, which is apparently called thinset in the US). The electric heat manufacturer says, "self leveling compound". Elsewhere, including one of the contractors, there are suggestions to use thinset.

warmsmeallup

It might be too late but Zmesh low voltage staples down to the plywood sub and the hardwood floats directly over the top. No mortar, no SLC, just the foam underlayment and the wood. It's a low voltage system so it will cost more upfront but how much are going to put into the prep for the line voltage cable system? All that goes away.

Oh yeah, you can nail through it all you want and it won't damage the element and since it's a slow growth heat, it won't overheat the wood.

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