I just built a small extension on my wood frame house. We are in the northeast (winters down to the low teens). We added three small rooms (mudroom, laundry, bath). They all now have hot water radiant heat in the floors:
- Separate thermostats/pumps for each room
- Two of the rooms have plywood/concrete/tile, with the tubing in the concrete.
- One has plywood/plywood channels/solid wood, with the tubing in the channels
- All are sitting on 6” deep joists on 16” centers
- All are over a 2+’ crawlspace that is connected to a full basement
- Crawlspace is not directly heated, but gets some residual heat from the basement which is uninsulated
My question is what to put in or on the joists to keep the radiant heat in the rooms above, not the crawlspace.
My choices seem to be either:
- 6” dense fiberglass insulation between the joists; or
- reflective barrier across the bottom face of the joists; or
- reflective insulation across the face of the joists.
Is there a compelling reason to use one over the other?
