Adding Insulation and Air Leak Sealing

Robert Robillard

11 years ago

Image: beforeyouinsualte.com

Insulation and Air Leaks

Adding insulation in your attic can drastically help reduce your heating and cooling bills each month.Lack of attic insulation and air leaks are usually the biggest offender for heat loss in a home.

The photo below shows ice dams on the upper main house and no ice dams on the newer lower addition. Both buildings have cathedral ceiling and “proper vents” running the lengths of the rafter bays.

I wanted to use these photos to show the difference between the two roofs.

2/3 of the upper roof was built in the year 1863 and are full dimension 2×8 rafters they were insulated with R-19 insulation.

The other 1/3 of the upper roof was built in 1992 with 2×10 rafters and is insulated with R-30 insulation.

The entire roof has a ridge vent and lower Hix vents, which is a continuous vent strip integrated on the roofing drip edge. The Hix vents are located above the gutter area – see photo below – this area is covered in ice. The problem with Hix-vents is that the snow and ice block the air flow.

In contrast, the lower roof, built in 2004, has 2×10 rafters and is insulated with R-30 high density insulation and all penetrations were sealed with expanding foam to seal all air leaks. The upper roof has a continuous ridge vent and the lower vents are located in the sofit and are not obstructed by snow or ice.

This issue is discussed in detail in my previous post: How to seal your attic air leaks and save money.

Solution: when the main building is ready for a new roof, rebuild the sofits and install continuous sofit venting.

Photo below – no issues. See earlier post on ice dams.

~ a concord carpenter

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