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jhzr2

Insulating an inaccessible hip roof space

JHZR2
9 years ago

A picture is worth a thousand words, so please see attachment. Essentially, part of our kitchen (under renovation) is under a hip roof that allows it to extend from the main walls of our four square home.

The area is completely inaccessible. Not high enough to stand or walk, the vertical wall is actually the exterior wall of two other rooms, no access panel.

Were doing renovation, and due to damage to the plaster in one spots and the lack of insulation and k&t wiring up there, we decided to pull it all down. Our intent is to install a tin ceiling in the kitchen, so our contractor will be putting up plywood.

But I need to know best practice for insulation. Our bathrooms have vent fans and the kitchen has a fan as well. Moisture has not historically been an issue and there is no sign of mold or moisture issues up in the space. But we do know there is decent heat loss.

So what's the best bet? I drew a picture of what I notionally think. A vapor barrier on the underside of the joist but above the plywood, and then batts or blown in insulation up above.

The space has NO ventilation. No holes in the soffits and no vent holes anywhere that I've seen. It does get full pm sun straight on (which surely helps with mold and moisture).

Since the vertical wall is part of an adjacent room (never any issues with craftiness or cold, I guess it's more protected then any other exterior wall), should it be insulated by either batts stapled to it, or foam board affixed?

Should I consider air sealing the stud pockets into this space? Because of a finished attic with decking,this could be an space to easily do it, but not sure if the house air balance would be funny with just these air sealed...

Thanks!

This post was edited by JHZR2 on Sun, Sep 14, 14 at 20:18

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