Air Tight

Airtightness is the key to a truly energy efficient home. After all, it doesn’t matter if your home is well insulated if it is leaking cold air (in winter) or hot and humid air (in summer). For this reason we put a lot of effort into making this home as airtight as reasonably possible. This post outlines the steps we took and the results we achieved. At the beginning of the LEED Certification process we attempted a blower door, and to nobody’s surprise the home was so leaky that we couldn’t even get a reading. The home was leaking everywhere; air was coming in around windows, all through the attic, and even straight through the brick! Because we wanted to dramatically improve the energy efficiency of the home we decided to go all in with a full set of new windows (casement, not double hung) that would be more airtight and make sense with the new layer of insulation on the exterior of the home. Therefore, the story if making this home airtight is largely the story of window installation. But first… the brick.

At the time I purchased the home it was painted grey, and looked pretty good! But the latex exterior paint was getting a little old and we were about to cover the brick permanently, so we wanted to make sure that we were doing the job right. Therefore I used an orbital sander to scuff and remove any loose paint and powerwashed the exterior. Then I applied a special paint / sealer:

Sherwin Williams “Sherlastic” Elastomeric paint. This paint is airtight but vapor open, which means that even though air cannot penetrate it, water vapor can. Therefore if in the future the brick somehow got wet, it would be able to dry out through the Sherlastic. This was my first step toward air tightness — to make sure air couldn’t pass straight through the walls. I put 2 coats on the entire house.

Coming soon… window installation!

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