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Rockdoggs3682
attic insulation
Rockdoggs3682

my region calls for r38
i have r13 now for a 6" joist.
i bought r30 and planned on running it opposite of my joist to give me r43
do i have to fill the gap up to the top of the joist before adding more insulation or can i proceed as planned or maybe push it down a bit because I'm over r38.

keith3267
Re: attic insulation
keith3267

If you get a continuous layer of insulation over your ceiling, there aren't many ways to do it wrong. You do not need to fill the rest of the area up to the tops of the joists except at each end of the joists. The air gap itself won't hurt unless it is open at either end, then warm air can move laterally and escape at the ends.

Be sure that you have a gap between the roof surface and the insulation at the ends of the joists for ventilation. A suggestion here, cut enough insulation into 6 to 10" strips to fill the cavity where the joists and rafters meet, patting it down enough, or using baffles so that air can circulate up from the eves into the attic. You can't run the batts perpendicular to the joists here anyway because the rafters will get in your way. Then run the rest of the batts perpendicular to the joists and don't worry about the gap formed where the new insulation goes over the joists. The extra dead air space will help a little actually, not a measurable amount but a little, in theory anyway.

Rockdoggs3682
Re: attic insulation
Rockdoggs3682

Sounds Good thank you very much for your help.

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