How Bout That Weather?
It’s been a mild winter, no question. We’ve spent all but like 2 weeks with highs well above average (don’t look it up). With the Jet stream getting increasingly drunk and wobbly, you never know what you’re gonna get. I suppose it’s same when I’ve had a few too many. Sure, we still get the occasional Arctic “I’ll tell you when I’ve had enough”, but this year the bitter winds decided to stay up in their room and brood. Allowing us down Up North to loose a layer and relax our gritting teeth.
This is part of why I was able to lounge shirtless on my back stoop over lunch last week and, like, enjoy it. You know, just working on my Valentine’s Day tan. I know the bill will come due, and the whole thing had an oily basenote and ashy aftertaste, but for about 20 minutes it was pretty sweet. A lot of this has to do also, with the microclimate we’ve created at Ω.
As I’ve mentioned, we looked at a lot of properties before we found our spot. In retrospect, I’m glad we didn’t end up at any of them, but each one we looked at (and then got priced out of) taught us something. I learned all about zoning and temperamental town boards. I learned about the recently updated flood plain maps, that are arguably already obsolete. Learned a bit about easements and HOAs and other things that made me glad I married a bureaucrat; that ain’t my language. We learned that the things to focus on most, were the things that were hardest to change. One of those things, is orientation.
Our goal was never to have a million dollar view, but if there was a view of any kind, it had to be the south. That way we could meet our building performance goals, and get a purdy view at the same time. In the northern hemisphere, the sun will primarily be in the southern sky, higher in the summer, lower in the winter. With strategically placed glazing (windows and glass doors), we can capture that sunshine in the form of “passive solar gain”. Windows on the north side of the house don’t provide that gain, and only serve as a heat loss. In the summer we’re able to block most of that passive solar gain (when it’s plenty warm, thanks), by having deeper eaves. As the sun moves higher throughout the spring, the eaves shade more and more of the house interior. East and west windows also provide passive solar gain in the morning and afternoon respectively. We have a fair amount of east wall glazing because it helps heat the house up a little faster in the morning, and also, who doesn’t love morning light pouring in?
West windows can actual create some unwanted passive solar gain, as the afternoon sun is usually unnecessary in the winter (it’s already warm in the afternoon), unwelcome in the summer (it’s already hot as hell in July), and is harder to block with deep overhangs. This isn’t as big a concern because it’s much easier to cool in the summer than to heat in the winter. The change in temperature (or “∆ T”) is much lower in summer vs. winter here: 20˚F (90˚-70˚) vs. 60˚F (70˚-10˚), respectively. The less you’re trying to change the temperature, the easier it is to achieve a comfortable conditioned space. Therefore, our first thought is always to winter heating, but summer cooling is still worth keeping in mind.
The other thing to keep in mind is the slope of the terrain. I read in a gardening book once that a 5˚ pitch to the south collects the same amount of solar radiation as flat ground 300 miles south. Not only does a slight southern slope make the garden plants happy, it also helps heat up the ground around the house a bit. The warmed ground then heats the air above it helping to create a toasty bubble around the house, or in other words, a microclimate. Everybody loves a good microclimate.
We obsessed over these details before we ever broke ground or even made an offer. And now we can sit back and reap the benefits without any extra cost, thought, or effort at all. Artificial Intelligence? This is Passive Intelligence. No massive, energy devouring server farms required.
But enough about the weather.
February last year was all about the house interior. The first project was the “shed roof vent chute”, a totally real thing I built.
This is a small but crucial detail. It’s important to make sure that the underside of any roof is “vented”, i.e. has a constant supply of fresh, outdoor air flowing against the sheathing (usually plywood or OSB). Partly to make sure that any moisture—either from humidity or god-forbid, a leak—can quickly dry out before allowing fungi to eat the sheathing, and partly to keep the roof cold. Giant icicles hanging off a roof are generally not a good sign and can indicate “ice dams”. If a roof gets warmed by heat loss through the ceiling, snow can prematurely melt. That meltwater can run down the roof until it hits the colder eaves (which don’t have a heat-leaking ceiling beneath them) where it can refreeze. If that ice builds up on the eave, it can cause the meltwater to “back up”, sneaking under shingles and wreaking all kinds of havoc. Extra underlayment under the lower rows of shingles are a good idea for this reason, but there’s no cure like prevention, and a well vented roof can often nip this problem right in the bud.
On the second floor, no problem. We’ve got vented “soffit” (the underside of the eave) that lets fresh air in, and a “peak vent” that allows exhaust air out without letting rain/snow in. In the attic, there’s plenty of space between the top of the insulation and the underside of the roof for unrestricted air flow. On the first floor “shed roof” it get’s trickier. Vented soffit lets air in, but the “peak” of the shed roof intersects a wall, and I’m not sure how venting a roof into a wall cavity would work. My guess is, poorly. Also, instead of “loose fill” cellulose insulation like the attic, we’re used a “dense pack” method for the shed roof. I’ll get into this more in a later post, but for now suffice to say, it doesn’t leave much room for airflow.
So, that’s the problem, what’s the solution?
A genius one, shared by building science wiz, Amber Westerman.
We built a “vent chute” on the underside of the shed roof sheathing. I nailed 1x2 furring strips to the sides of the roof trusses (our version of rafters) right along the underside of the sheathing. Then I installed 1/2” thick asphalt coated fiberboard on the underside of the furring strips. This created a 1 1/2” air gap between the underside of the roof sheathing and the dense pack insulation in the shed roof truss cavity. Then I cut a 1” wide strip out of the roof sheathing an inch or so down from where the shed roof intersects the wall. This is our exhaust vent. When we installed the metal roof, we were able to “flash” that vent in such a way that air can get out but water can’t get in. And voila! A shed roof vent chute. Totally real.
After that I airsealed the second floor ceiling and built the 2nd floor interior walls, but that’ll have to wait for the next post, cause I spent half this post talking about the weather, and now I need to go make dinner.