In addition to being highly insulated, our house is meant to be very airtight to prevent heat from escaping. To achieve this, any gaps or openings need to be filled to prevent air leakage. With rough ins mostly done, we needed a blower test to gauge how well it had been sealed. With this test, a big fan is attached to a door to move air through the house while measuring the rate at which indoor air is replaced by outdoor air via any unfilled holes. The lower the score, measured in air changes per hour (ACH), the more airtight the house is.
On the first test, the house scored 1.6 ACH. While a typical new home would have a score around 3 ACH, for our purposes, this was a fail. And the testing team was stumped, unable to find the source of the leak. They suspected air was passing beneath the wall studs. The energy auditor suggested we try Aerobarrier, an acrylic sealant product that is sprayed as a fog inside the house to seal any gaps. This got the blower door test down to 0.19 ACH, though it made our floors very sticky – we’re hoping this washes off easily. Our final pre-drywall test this week was 0.57 ACH. We’ll have one more test after drywall is done.
With the blower door test done, we were able to get to work adding the final layer of insulation in the service wall. We did that work ourselves. Installing the Rockwool was straightforward, though we were disappointed to find that many of the studs in the service wall were not spaced at 16 inches on center, necessitating a lot of cutting of batts. It was dusty, itchy work, but satisfying in the end. With the temperature swings in recent weeks, it’s neat to feel how well the house is holding its heat. It has felt noticeably warm on cold days and cool during a short hot spell.
With spring here, we’re racing against nature to get the house sealed up again. A pair of mourning doves has been trying to move into our attic via an open access and nest in the porch, presumably to establish squatters’ rights before we gain occupancy. They fly over to roost on the roof as soon as they see us pack up the car, taunting us from their perch. We hung plastic, over the porch but they were persistent and pushed through, so we went back with a sturdy tarp and some old shower curtains, which seems to be holding them back for now.
The exterior wrap of our house is nearly done. The siding installers still need to finish up the garage and house walls inside the screened in porch. We went with corrugated metal siding and are happy with the look. It cost more than vinyl but much less than fiber cement or wood. We were attracted by the durability, longevity, and minimal maintenance required.
This week, we’re pushing to have the electrician wrap up so the drywallers can start. We’re also mapping out the next few weeks and scoping what other work we’ll do ourselves to get us to the finish line by July 1.
Marlborough Forest House 