radiant floor with aluminum plates

Snowmelt

i have a question, the last bay at a job sight is only 10 inches are so. so i can only get one track in there would it be wise to put a track on the outside wall as close to the top as possible, to help prevent the cold air from coming in?

STEVEusaPA

I would think you would want insulation to stop cold air from infiltrating. To me, cold air would extract heat from the tubing.

Zman

The outside joist bay/rim area are usually inadequately insulated and tend to leak air.
Unless your builder is conscientious about this and is using spray insulation, I would keep the tubing out of that bay.

STEVEusaPA

Keep in mind if that last bay is 10 inches, a 2x6 wall above it flush to the exterior, more than half of that bay is probably under the wall, I'd just insulate it.

hot_rod

The key is to get all the tubing that the design called for, installed. Don't skip a bay and shorten that loop.

If it is the outer most joist bay, the wall is above a portion of it, I'd just pack that one with insulation. Your highest delta T is that outer joist where ambient outside temperature is only 1-1/2 or 2" away from inside air temperature. Spray foam first to seal any air gap and pack a large fiberglass batt in there. Same detail for rim joist where the joist ends nail to the rim board, fill up that space with insulation.

Run 4 tubes in the last space if you need to use up the loop, two in plates two just fastened to the subfloous areu'h in