So I’m re-insulating the ceiling of my attached garage 26x24. On top of the garage is a 16x20 room, and the garage roof has a 4/12 roof pitch. 6 feet horizontal from room wall to garage wall, and 28” from top of garage rafter/joists to top of garage roof where it meets the room walls.

Now the soffit is vented and so is the roof, yet when I got the insulation down I noticed 2 ‘errors’. First there are no rafter vents, and actually have the gap stuffed with insulation pieces.

Secondly the ‘knee wall’ (room walls facing the garage attic) have no plywood or wrap/tar paper, just the insulation.

This house was built in 1990, and what is now a room above the garage was initially a deck. The insulation was all installed by my uncle who has some construction knowledge, but far from enough. He insulated the ceiling and room walls about 20 years ago.

The room has 12 windows, 8’ walls and good insulation in its ceiling. Yet the room is a bit cold in the winter and hot in summer. My guess is the knee walls are partially to blame.

I presumed the rafters were vented, and when I first seen the unsheathed knee wall I thought finishing that would make A huge difference. Yet the unvented attic would certainly be warmer in the winter I’d guess.

There are no signs of condensation in the attic, and I’m wondering if the attic itself is small enough to not need venting? If I didn’t know it’s spent 20 years un-vented I wouldn’t even consider closing off the rafters. Yet perhaps the insulation stuffed in there is just enough to let minimal air through.

Does finishing the knee wall exterior with plywood, and Tyvek along with spray foaming and sealing all gaps sound like the way to go?

should I put rafter vents in and ‘fix’ the error? Sounds like a stupid question but such a small attic space, with 56 feet of soffit to allow air flow, when it’s been seriously restricted for 20, something that will make the room more comfortable.

Although I suppose the walls wouldn’t be any less insulated then any other exterior wall, and yet protected from the elements.

Ya, maybe they are stupid questions now that I’m asking them, lol.

Anyways advice would be appreciated.