Radiant Floor Insulating

[Junkman]

Does a second floor that has radiant heat applied to the sub floor have to have insulation between the floor joists and the sheetrock ceiling in the first floor area? My thoughts are that since the first floor is already a heated space, that since the heat rises, that the area above the sheetrock is already warm, and that any heat that will be transmitted below the second floor subfloor will be negligible. If it needs to be insulated, can blown in insulation be used?
thanks

 

[pstnbly]

Yes.

 

[Randy in Maine]

Radiant heat radiates, it does not always rise.

 

[Junkman]

The radiant heat pipes will be set in the Uponor tracks, which will be screwed to the 3/4" subfloor, and then covered by 3/4" hardwood flooring. All of this is on the second floor, which is going to be difficult to insulate. The only way that I can think of insulating it would be to have an insulation contractor blow insulation between the subfloor and the sheetrock ceiling. I am not certain how that will work out, because I don't know if there is any blocking between the joists.

 

[Wook660]

I'm confused. How are you going to attach the tracks to the subfloor without removing the sheetrock from the first floor ceiling? If it isn't yet sheetrocked, than put the insulation in before you sheetrock. The battons go right up against the pex and will stay in place when you hang the sheetrock.

 

[Junkman]

Uponor makes tracks that both mount on a subfloor, or under the subfloor. I am using the 7"wide X 48" long plywood track / boards that mount on top of the subfloor. Sorry if I wasn't clear on that.

 

[brewchief]

They can blow in cellulose pretty easy, if there is blocking they will just need to drill a few more holes, not a big deal. We had my buddies shop insulated like that, ended up with two 2" holes per joist bay, we just gooped the plugs from the holesaw with liquid nails and pushed them back into the holes to seal it back up.