Buttoning up the radiant heat floors...

It's brutally hot and humid here in Kentucky now, which makes it an odd time to be discussing radiant heat, but I'd like to describe the final details of our radiant floors as we implement them.

I fired up the system this past winter and it worked great for heating the house and keeping our feet warm. In fact, the home-made aluminum transfer plates (10 to 15 cents apiece thank you!) were so effective that when we walked on the floors, we could feel exactly where the plates were located. But because we hadn't installed our ceilings yet, we had a lot of misdirected heat. The radiant tubing in the first floor inadvertently heated the basement, and the radiant tubing in the second floor made for hot heads on the first level of the house (with heat coming from the ceiling, it felt like talking on a 1990's cell phone for 2 hours). Before installing our finish ceilings, I took precautions to ensure that very little of our heat gets misdirected in our finished house.

The photograph shows what's above the ceilings in our timberframe house. To the left, you can see the PEX tubing affixed to the subfloor with aluminum transfer plates. The tubing runs left to right (and vice versa) in the picture, between 3x3 oak floor joists. The floor joists and the tubing are on one foot centers. (I used 3x3's instead of 2x4's, because I cut them on my own saw mill and this gave me two chances to saw the 3" dimension without bow or taper.)

In the middle of the photograph, you can see a layer of heavy aluminum foil stapled beneath the floor joists, but above the tongue and groove ceilings. This foil is made specifically for reflecting radiant heat and can be bought on the internet or at a box store. (We found ours at Lowes.) Even though a lot of web sites say that kitchen aluminum foil won't work, I'd bet that it would work. But the purpose-built stuff is better if for no other reason than it has "scrim" or fiber embedded in it and therefore does not tear easily. Because I was working alone, I used a few ceiling boards to hold up the aluminum foil while I was stapling it up.

In the right of the picture, you can see the (tulip) poplar tongue and groove ceilings installed beneath the aluminum foil. The ends of the boards merely sit on top of the timber frame beams. I avoided nailing any of them, so if at any time I want to remove the ceiling boards (to reroute electrical wiring or to repair radiant floors), I can simply slide the tongue and groove boards back out of the way. (FWIW, the poplar boards don't actually look bone white like the picture - they have a green hue which mellows to a nice buttery brown color in a few weeks.)

Well, that's it. Rinse and repeat.