Today’s DIY Question

How to install radiant barrier for under floor heating

by | DIY Questions

Bill asked

I recently installed radiant tubing in my unfinished basement ceiling. The floor joists are 16″ O/C engineered trusses. The trusses are 2′ in depth. I would like to install bubble-foil to reflect the heat up but cannot get a good seal because of all the bracing in the truss. If I install the bubble foil on the bottom of the truss, will I loose the effectiveness of the radiant heat installation. I was told the closer you install the foil to the tubes, the better it forces the heat into the floor, but what good does it do if I cannot get a tight seal. I have 1,800 s/f of area to insulate.

DIY Answer Guy

Hi Bill, great question about installing a sub-floor radiant barrier. That’s quite a project you’re working on. It’s true you would lose a bit of heat having the radiant barrier farther away from the heat source, but not an appreciable amount. And you’re right, a leaking radiant barrier isn’t effective.

So install the radiant barrier on the bottom of the trusses and be sure to use foil tape to seal the seams.

underfloor radiant barrier

If you haven’t bought the radiant barrier yet I’d suggest using the one with the closed cell foam in the middle, as it is the best for the money.

Here’s a link to the supplier I use and recommend. Prodex If you have any other questions let me know, and best of luck with your project. For sure you’ll be warm this winter.