Air Sealing Case Studies: Commerce Township, MI - Air Sealing Under Shed Roof (Deep Retrofit Measure)

Tuesday, July 14th, 2015 by Kevin Bailey

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Challenge

This shed roof is connected to the interior of the house. This is a common design that is always under insulated and never air sealed. In this case, the air leakage was producing moisture and actually causing condensation build up on two walls connected to the exterior wall. This occurred in both rooms that sit directly above the shed roof on the second floor. There was also a bay window (located under the shed roof assembly) that was exposed causing significant discomfort in the living room below due to air leakage.

Solution

In order to eliminate the excessive air leakage we needed to properly air seal and insulate. The area treated was the interior walls of the 2nd floor and ceiling over the first floor of the house positioned under the shed roof. This involved performing a complete tear off of the shed roof allowing us access to the interior walls of the second floor, the ceiling of the first floor, and the ceiling of the bay window. Next we performed our Hybrid Treatment to those areas. This two step process entails first: air seal all exposed areas with one inch of 2-part spray foam. Secend we added R-49 of blown-in cellulose over the entire ceiling area and at bay window. This treatment provides the proper seal to stop air movement from the outside, and enough thermal resistance to keep these areas inside the house warm in the winter and stay cooler in the summer

Second floor walls and first floor areas affected by under insulated shed roof

After roof tear off. Area only has fiberglass batt.

Evidence this area is very leaky. Fiberglass batt is black due to constant air flow thru this area. The moisture causes this discoloration.

The ceiling with an electrical junction box, wire penetrations, etc. is an area where air is leaks that must be sealed. Along with the rest of the entire ceiling portion

The ceiling with an electrical junction box, wire penetrations, etc. is an area where air is leaks that must be sealed. Along with the rest of the entire ceiling area