piffin I have an insulation question you
silvertip
| Posted in Energy, Heating & Insulation on
I have a bump out on my second floor addition that sits into the garagae roof. I have installed rigid insulation between the I joists tight to the underside of the floor sheathing. It is acoustical sealed all around the edges and the tucked taped. I would like to install batts in the I joist space but do I need to worry about an air space so I don’t end up with mold. The garage will be heated.
Replies
How is garage heated?
How is the room above heated?
to what temperature will it be heated?
will it be used as a garage or as storage/workshop?
Why is the rigid foam where it is?
Is this a closed cell EPS or XPS, or is it open celled foil faced polyisoanurate?
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You ask a lot of questions for what I thought would be a simple answer LOL. The room is a ensuite bathroom which will pick up the heat from the rest of the house. I was thinking of putting in in electric in floor heating. It will be used as a workshop. Minumn temp in the workshop unless I am working in there. It is closed cell rigid insulation the stuff used to insulate the exterior foundation walls. I put the rigid there to keep the cold transfering to the floor above to keep the tile floor from getting cold. Now that I have started to insulate the garage trusses and putting up a vapour barrier I got to this area and was curious if I insulate the roof space as normal and not worry about air circulation. I will post a picture if I get a chance. The space below the floor is 9 1/2" plus another 6" to the ceiling.
I am not sure I understand your structure. However you need to keep moist interior air from entering the subfloor cavity as much as possible. Your closed cell foam etc. should be good. Other possible infiltration routes need scrutinity as well (ie. laterally in the joist cavity and up from the garage if applicable). Then you need to be sure any moisture that does accumulate is not prevented from working its way to the outside or unheated space. (ie. no vapour barriers between the subfloor cavity and the outside.) Basically you need materials which provides a vapour barrier on all the heated sides and permeable materials on the rest.
The questions were necessary to determine moisture drive direction.I think you'd be fine with any insulation there and no need for an air channel.Sounds like you are as concerned with sound insulation as with thermal barrier there, so I would recommend using strapping on the bottom side of the joists before doing the sheetrock on the garage side.
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