Electric radiant heat under hardwood floor

jws13

New here, so hello and thank you in advance.  I'm going to be putting down 3/4" by 4" wide pre finished hardwood in the master closet and plan on putting electric radiant heat in the adjacent bathrooms under tile flooring.  I would like to put the heat under the hardwood, but everything I read appears to say that I'd have to place the hardwood on sleepers.  I'm wondering is there anyway to do it directly under the hardwood if I'm extremely careful with the nailing the staples?

Jamie Hall

Is this cable or mat type electric radiant? If it's cable, you'll be much happier with the flooring on sleepers -- nominal 1 inch is ample -- with the cable between them. Two reasons: first, you are much less likely to damage the cable during installation, and the other is that the cable won't overheat the flooring locally where it is in contact -- which, otherwise, it will.

Mat type... the only thing I'd put over mat type along those lines is the type of flooring which is called "floating", which snaps together and isn't fastened to the subfloor at all. Otherwise will damage the mat -- pretty much can't help it.

And in either case be sure you have a floor temperature thermostat to limit the flooring temperature. Never allow either type to go over 80.

hot_rod

I know electric cables are installed under Sheetrock, check with various manufacturers for under subfloor installation.

Or use pex with a small 6 gallon electric water heater as the source.

jws13

Thanks....I was thinking cable type in order to minimize chances of damage and thinking if I were to b put down some sort of reflective material under the cable it would help spread the heat.  Trying to avoid the sleepers because it would raise the floor height 

Jamie Hall

Cable without sleepers... um... well, even if you manage to miss the cable with the nails, you will be squashing the cable. And cables don't like that.

jws13

I appreciate your feedback and hoping others will provide their thoughts and suggestions.  In order to prevent squishing I could router a channel in the subfloor... hoping someone will let me know if this is even feasible or better yet have they done something similar... thanks 

hot_rod

jws13 said:

I appreciate your feedback and hoping others will provide their thoughts and suggestions.  In order to prevent squishing I could router a channel in the subfloor... hoping someone will let me know if this is even feasible or better yet have they done something similar... thanks 

Your best info would come from the manufacturer of the brands you are considering
They are built and listed to specific installation methods, for good reasons😉

I would not recommend an installation method that is not approved by the manufacturer 

jws13

I had thought of that but never followed through, until last night.  Sent a manufacturer the question, I'll post on this thread what I find out... thanks 

jws13

Just wanted to get back with the group and let you know that I just got off the phone with a company that does provide a solution that I was looking for so basically an electric radiant system that goes down under nailed hardwood that you don't have to install sleepers the company's name is thermosoft and the product is called warm step radiant heating mats and they say that it only raises the floor thickness by 1/16 of an inch haven't tried it yet but I thought I'd share it.  If anybody else out there has done it let me know thanks and appreciate all the help

Jamie Hall

Thank you

hot_rod

UL listed? Make sure it is not some knock off import with fake listing shields.
Just to be safe.

jws13

Looks like a decent company with lots of approvals and made in USA

hot_rod

I remember some  of the low voltage mats you could put a staple in the wrong place  and it didn’t take out the entire mat