A lot of volunteers gathered in Decatur, Georgia this past weekend for the annual Martin Luther King Jr. Service Project. They worked at a number of sites doing all kinds things to improve the homes of low-income senior citizens. The jobs volunteers worked on included cleaning out homes, replacing broken stuff, installing handicap ramps, general maintenance, and more. I participated this year and was on a crew led by Mike Barcik, a friend and former colleague from days working at Southface. Our job was weatherizing an old house. Here’s how it went.
A huge hole beneath the sofa
If you’re doing a volunteer project to weatherize an old home in three days, you want to look for the low-hanging fruit. That is, find the stuff that will make the biggest difference with the least amount of work and that volunteers can be shown how to do without much difficulty. The house I helped with had one huge piece of low-hanging fruit that Barcik is pointing to here.
Someone pulled the sofa away from the wall in the living room and exposed a huge hole in the air barrier. It looked like an ordinary return vent in the floor, but when they removed the grille they found there was no duct attached. That 12 inch diameter hole was wide open to the vented crawl space below. That meant that drafts, moisture, and critters had easy access to the living space.
The fix began with using mastic to encapsulate the tape on the duct below. That kind of tape on old ducts almost certainly contains asbestos, so this is a good way to keep the fibers out of the air. Then they put three layers of foam board into the hole, sealing around them with spray foam. Then the grille went back over the now sealed hole.
Typical attic kneewalls
In weatherization world, any wall that separates unconditioned attic from conditioned space is called an attic kneewall. They’re notorious sources of comfort and energy efficiency problems. Why? Here are the main reasons:
- Lots of air leakage sites
- Fiberglass batt insulation installed poorly
- Open floor joists that allow hot or cold attic air to get under the conditioned space floor
I’ve written about kneewalls several times in this space (see related articles below) and also spent quite a bit of time fixing them back in my contracting days.
The attic kneewalls in this house had the typical problems. You can tell that room on the other side of the kneewall had problems because there’s a window unit air conditioner in the kneewall. The photo above shows Energy Vanguard’s Jeffrey Sauls getting ready to fix one of the kneewalls before we did anything to it. The lead photo at the top shows Chris Thiele working on that same kneewall.
And the photo above shows what that same wall looked like at the end of the long weekend project. The fiberglass batts are now covered with rigid foam insulation, and the seams are sealed with tape and mastic.
It’s important to fix the whole kneewall, though. The photo above shows the foam board and spray foam sealing everything up at the bottom. The devil, as always, is in the details.
A wiring warning
When weatherizing an old house, it’s important to understand the risks that come with the territory. In this house, the risk that threw up a roadblock was the old knob-and-tube wiring in the attic. This is a hundred year old house, and that’s what they had in the 1920s.
So what does this mean? The Building Performance Institute (BPI) has standards and certifications for energy auditors and says this in their technical standard for envelope professionals:
Insulation may not be installed where live knob and tube wiring exists.
The problem is that the cloth insulation isn’t durable and can expose live wiring. That could lead to electrical shocks or fires.
So we tested. The photo above shows the tester lighting up red, indicating that the wire is still energized. So were all the others we found. That meant that we couldn’t add insulation to the attic floor until the knob-and-tube wiring all gets replaced.
Working at the eaves
Even though we couldn’t insulate the attic over the weekend, we did get it ready for insulation. The prep work consisted of doing two things at the eaves. First, the house had balloon framing in the exterior walls, which means the walls were open at the top.
In the photo above, you can see a piece of foam board sealed into place at the top of one of those uncovered wall cavities.
The other prep job was to put insulation dams in place to keep wind from blowing through the insulation and degrading its effectiveness, as you see in the photo above.
One improvement in the basement/crawl space
I spent my working time in the attic, but volunteers also did a little work in the basement/crawl space. They insulated the water pipes. With the weather that’s has come in since the weekend—a low of 14 °F (-10 °C) this morning—that probably made a difference for them.
Giving back to the community
I was one of many people who worked during the MLK Service Project over the holiday weekend. This article in Decaturish has a lot of photos showing some of the things that people worked on.
I think we made a significant difference in weatherizing an old house for that family in Decatur. The reduced air leakage and improved kneewalls should help with comfort and energy efficiency. If you’re in the Atlanta/Decatur area, consider donating or signing up for next year. If you’re not local, look for similar projects in your area. If there aren’t any…hey, you can start one!
Allison A. Bailes III, PhD is a speaker, writer, building science consultant, and the founder of Energy Vanguard in Decatur, Georgia. He has a doctorate in physics and is the author of a bestselling book on building science. He also writes the Energy Vanguard Blog. For more updates, you can subscribe to Energy Vanguard’s weekly newsletter and follow him on LinkedIn.
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