According to code, a garage is considered an accessory building when detached from a dwelling, and outside the conditioned envelope when attached to the dwelling structure. They don’t fall under the same energy code requirements as a dwelling. That being said, it’s common in my market for both attached and detached garages to have some sort of heat source (I live in a very cold climate). If you are going through the trouble and expense of conditioning a garage, it’s probably wise to also think about its efficiency, both insulation and air sealing.
I have several blog postings dealing with attached, conditioned garages on the Northern Built website. It’s been my experience when testing new homes, the attached garages are not separated well enough from the home and often could use improved air sealing when conditioned, especially in my very cold climate.
I recently ran into this garage door seal which I have not seen before. It has the traditional outer seal that is attached to the side jamb of the door opening, common on all garage doors in my market, but this one has a second seal that is attached to the inner door framing along side the door track. I had a quick conversation with the installing company which they said the door is ordered two inches wider than the opening to accommodate the inner seal.
There is an additional seal attached to the top of the door to provide further air sealing.
I have yet to determine if this improved garage door seal is available through Clopay, the door manufacturer on this new home build, or if it is an aftermarket product, I will update this posting when I know. I have a final blower door test to conduct on this home in the near future. I plan on testing the garage separately to determine if the door seals do work, and how connected this garage is to the main home stay tuned.