Jun
30
Cathedral Sunroom
Filed Under Sun Rooms
Will Sheetrock bulge if insulation wrong size?
I am insulating a cathedral ceiling in My Sunroom with R-30 insulation which is 9 inches thick when fully opened.The rafters are only 2 x 6′s .I am using vent the entire length of ceiling to remove mouisture also using 1/2″ sheetrock.Will or can the insulation bulge the sheetrock.It is also in a conditioned area.
The vent is from the eves up to the roof ridge on the roof side.The rafters are also on 16″ centers.Will 5/8 sheetrock work better?Thanks for the great answers
Yes, 1/2″ Sheetrock isn’t strong enough to hold back the insulation, so it will bulge. It may even cause the fasteners to go right thru the Sheetrock= Sheetrock falling off the ceiling!! Also, when the insulation gets compressed, it loses it’s R-value. 9″ R-30 squashed down to 5 1/2″ may only yield R-20 or so. If I were you I would either return the R-30 and get insulation that will fit in the cavity, or build out the thickness of the 2×6 rafters by adding 2×4′s to the bottom.
You say you have a full length vent for moisture. Is this on the roof or on the room side? You will also need a vapor barrier, on the ‘warm’ side of the insulation. In cool and temperate climates that means the inside. In Florida, that’s the outside.
