attic hatches, knee walls and attic stairs

Knee walls (short walls built between the rafter of attics and the second floor), attic hatches and attic stairs are typical sources of air leakage and low-energy efficiency, and a cause of discomfort. They are often associated with large cavities, holes, and air penetrations with a huge impact…

Knee Walls Air Sealing

Sealing the holes and penetrations related with these structures is crucial to solve air leaks and their paths. The image at right (from DOE) illustrates the air leakage mechanisms and their sealing.

Materials and application

To seal attic hatches and knee-walls you should seal the joist cavities under the floor below them. It’s mandatory to create a rigid seal: add rigid insulation to achieve it.

To solve air leaks in attic pull-down stairs, weatherstrip the openings and add an insulated cover. Also make stairs airtight (you may use latch bolts…).

 

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