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Tighter building envelope

Your Roof Replacement Affects Your Building Envelope

Home improvement projects can be great opportunities to make your home more comfortable and energy efficient.   I replaced a portion of my roof this summer because it was due for an overhaul. As part of the process, I included some extra steps to improve the efficiency of my building envelope and increase comfort. I filled the roof cavity with high performance insulation, replaced existing skylights with triple-paned versions and switched to lighter colored shingles for better solar reflectivity. No more shivering on cold winter mornings!

What’s a “building envelope”?
The air tightness of your building envelope—defined as your exterior walls, roof and basement that surround the space you heat and cool—tops the list of areas to improve when the opportunity presents itself. A tight building envelope with controlled ventilation maximizes comfort and energy efficiency by keeping outdoor air out and indoor air in. In existing homes, some work is only cost-effective when done in conjunction with a necessary improvement project like re-roofing.

The old building envelope
Removing the old roof

My process
If you buy an existing home rather than building your own, some of the opportunities for a creating a tight building envelope have long since passed, but improvements can occur. I live in an older home that was very drafty when we moved in. My cathedral ceiling had almost no insulation. Once the old roof shingles were removed, the insulation contractor jumped in and filled the cavity with dense-packed cellulose before the new sheathing and shingles were installed. Although it takes willingness on the part of the roofing and insulation contractors to coordinate, I’ve had success with this approach for myself and for clients.

Achieving a high performance building envelope
Lots of cellulose insulation!

I researched high quality triple-paned skylights to replace my 20-year-old double-paned ones.  It’s a good idea to replace skylights as part of re-roofing to avoid having skylight leaks develop after a new roof has been installed.

Since I wasn’t replacing my entire roof at one time, I was forced to stick with asphalt shingles but took the opportunity to choose a light-colored style to improve solar reflectivity and with a very long useful life.

All-in-all, a successful project which, with some extra thought and coordination of trades, noticeably improved my building envelope and overall comfort.

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