Knee wall attic insulation

[Brandon Whitmore]

New construction inspection.

The builder installed unfaced batt insulation in the rafter cavities in the knee wall area. The batt insulation is then covered over with a white plastic type membrane-- pictures will follow.

I am curious as to how to be sure there is the required gap between the insulation and roof sheathing. I already know they did this wrong , at least in some areas---- several of the eave vents screens are blocked by the insulation as visible at the exterior of the home.

Also, what is the best way to air seal openings / gaps in the plastic membrane, such as where the B vent and plumbing vent pipes penetrate?

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[hausdok]

Originally posted by Brandon Whitmore

New construction inspection.

The builder installed unfaced batt insulation in the rafter cavities in the knee wall area. The batt insulation is then covered over with a white plastic type membrane-- pictures will follow.

I am curious as to how to be sure there is the required gap between the insulation and roof sheathing. I already know they did this wrong , at least in some areas---- several of the eave vents screens are blocked by the insulation as visible at the exterior of the home.

Also, what is the best way to air seal openings / gaps in the plastic membrane, such as where the B vent and plumbing vent pipes penetrate?

Is it a permeable membrane or just plastic? I'd use Airlok - latex mastic.

ONE TEAM - ONE FIGHT!!!

Mike

[Brandon Whitmore]

Mike,

I usually just see the clear or whitish plastic, but in this case it was a little thicker-- more permeable looking though... more like a weather resistive barrier look to it.

Worst case scenario with the air leaks, what would you expect to occur?