Tuesday, December 28, 2010

Sealing Out the Drafts

Winter has arrived yet again, and our struggles to maintain an efficient - and more importantly, comfortable - 100-year old home continue. This is a battle I wage with elements every year as things turn cold.

This year, I've become increasingly knowledgeable about a little thing that is hard to see and really adds up - air. Or more specifically, air leakage, an important aspect of green building. Although we performed a blower door test over a year ago, there continue to be opportunities to improve the air leakage in our home.

So after learning some building science, its useful to know that in addition to heat rising, the upper levels of a home are constantly under more pressure. Heat and air both rise, creating a chimney effect in a mult-level home. This static pressure causes air to want to find its way out of the house, particularly in second floor converted attic like we have.

With this in mind, I recently went around our second floor to address these air leakage issues. The largest losses on the second floor are in all the ceiling penetrations. The recessed lighting cans and built-in speakers have been great and provided clear headroom, but when installing them we could have been a bit more careful. The biggest regret I have is buying the big-box special recessed lighting housings. We purchased the insulation contact (IC) rated housings, which were important so insulation could come right up alongside the lights. However, had I spent a dollar or so more on each light housing, we could have had air-tight insulation contact (ICAT) housings. As this article explains, regular recessed lights allow for a ton of air leakage. Note to self: when buying these in the future, hold up to the light in the store. If light comes through, so will air!

Oh well, fortunately, many of our recessed lights in the attic have an air-tight shower trim kit. We liked them because they have a flat, not-quite-interrupted surface. Now, I'm glad they help fend off air leakage too. Additionally, I recently took to time to caulk between the drywall and the metal can to eliminate further leakage around the cans.

While I was messing with the ceiling, I also took down the smoke detectors (we have 3 upstairs). Underneath one of the smoke detectors, there was a significant amont of dust - enough to form a ring around the collar! I knew it would take more than Wisk to make this ring go away. Dusty signs like this - after just two years since installation - is a tell-tale sign that there is some major air leakage and heat loss ocurring here.

After removing the smoke detector mounting bracket, I pulled out one of my new favorite stocking stuffers, Dap Latex Foam Sealant, a great easy-cleanup spray foam that is water-based instead of oil-based (like Great Stuff).

I also used the spray foam around some of the air return ducts that weren't sealed to the drywall, and plugged a few other holes with what remained in the can.

After all of this, I think our second floor bedrooms in the converted attic space will be more comfortable this year. And, this may be a surprise, but this will likely make the basement more comfortable as well. Why? Well what happens in the basement has everything to do with what happens in the attic.

It goes back to that static pressure concept - when air is lost through the attic,
it comes in at a lower level such as a basement or, even worse, an attached garage (think of all the chemicals and fumes stored in a garage, and how that air might come in if the attached garage is the weakest link in the air barrier). We are fortunate to have a detached garage, so we don't worry about this. However, if we make it harder for that static pressure to force air up through the attic, it means less air will be pulled in from the basement, keeping that a bit cozier and healthier too.

All in all, it took more time to write about this than it did to actually seal up some of these holes, so I'm hopeful we'll get a more comfortable home with this small investment. With the Chicago winter underway, every little bit of comfort and energy savings helps Humphrey House be a happier and greener home!