Building Better

It’s been a wild month since I last had time to write a few words. I’ve been getting started early to make the most of the dwindling daylight I’ve got to work with, and trying to write—or even think clearly— after a long day is a non-starter. Luckily, I guess, there’s a wind chill of about 10 degrees this morning, so I’ll take that as a sign or something.

The basement ICF forming was a dream. Truly Legos for grownups. Kept track of level/plumb/square at every course of blocks, and braced the ever-loving shit out of them, and we had ZERO blow-outs, or disasters of any kind on pour day. Even so, if I could do it again I’d do it a little different, but ain’t that the way. We ended up with a foundation wall that was ready for a sill plate.

Post-pour/pre-sill

A sill plate, or “mudsill”, is usually the first piece of wood that goes on a house. It connects the concrete foundation to the wood framed floors and walls. A rot resistant board (treated or cedar as all wood should be when it sits on crete), gets bolted to the foundation in the exact dimensions of the building that sits atop it. Those bolts are usually set into the wet concrete with threads exposed that slide into holes in the sill plate. We instead used a Simpson Strong-Tie product called Titan HDs. These are basically giant Tap-Cons that screw through the sill plate into a 1/2” hole drilled into the foundation. It’s the only method I’ll use if I ever do this again, which hopefully I won’t. They’re pricier ($4 each vs $0.50 each for traditional anchor bolts) but worth it in my opinion for my project. Best of all, I believe it made sealing the mudsill easier, which is good because, hoo-boy did we have to seal that mudsill.

Post-pour/post-sill

I should explain: we’re trying to build a really kick ass house. Kick-ass is an utterly subjective term. For Dani and I it means a house that does everything we need it too, and nothing we don’t. A house that facilitates our efforts to be as self-reliant as possible, which we’re both…ummm… passionate about, to put it mildly. We want a house that’s warm in the winter, cool in the summer, and uses as much sweat and free sun as possible to maintain that comfort level. That means going the extra mile and spending a couple bucks if it translates to a more durable and energy efficient end product.

Let’s talk about energy efficiency for a second. Energy efficiency in a house means using less energy to maintain a comfortable conditioned space. This results in homeowners keeping money in their pockets at the expense of the fossil fuel industry’s gross sales. While I think “Good” and “Bad” are terms often too simple for a complex world, both of these are categorically good side effects. That said, while our carbon footprint is certainly a factor to consider and lowering it is a bonus, it is not our One Guiding Principle. For example, one of the ways we’re achieving our efficiency goals, is by using a bunch of EPS foam-board which uses a bunch of petrochemicals to manufacture, among its other negative impacts on the environment. However, it’s (arguably) not as destructive as XPS foam-board, which is (arguably) a better insulator than EPS. Trade-offs and hard choices—such is adulthood. I prefer to think of it as an investment of fossil fuels; a front-loaded footprint. I tip my hat to those who save every last molecule of CO2, or CH4 from going up there; but we’re all just doing our best down here and money is in-fact an object for the Ω Build.

There are 2 main ways a conditioned space loses it’s conditioning: conduction and infiltration. Heat is conducted thru different materials at different rates (think down parka vs. cast iron skillet), generally referred to as its U-value. Heat moves through wood pretty fast, making wood a pretty bad thermal insulator. It moves through concrete 10 times as fast as wood, making it one of the worst thermal insulators. This is where insulation comes in handy. Insulation has varying levels of resistance to the transfer of heat (AKA its R-value) and slows the equalization of interior/exterior temperatures through the solid materials of a house. More/better insulation = slower heat transfer through a solid wall.

The second way a house becomes “unconditioned” is through infiltration, which just means air leakage, generally expressed in air-changes per hour, or ACH. The tighter a house’s “envelope” is, the lower the ACH is and the less heat gets lost through infiltration.

“But wait, can’t a house be TOO tight? Don’t leaks help a house breathe?”

In a word, no. Any conditioned space needs fresh air, for sure. Ventilation, both intake and exhaust, are super important. However, random leaks in a house’s envelope are a shitty way to get that ventilation. This is a worn out excuse for cutting corners to make money on a low bid. Houses built with a tight envelope and little to no ventilation do often suffer from condensation and air-quality issues. A lot of houses in the 15-25 year old range have this issue, which is a result of building tight without adding ventilation, which is a result of not thinking about a house as a holistic system, which is a result of profit motives and tunnel-visioned trades dictating innovation without any collective-minded guidance, which if you think about it is exactly what’s happe——….

Sorry. What was I — infiltration, right. We’ll be doing both: building tight and ventilating adequately. And that all starts with our mudsill seal. Anywhere different materials and/or trades come together is a good place to take extra care. Generally, a “sill-seal” gasket is place between mudsill and concrete.

EPDM Gasket:

Better, bigger, stronger, squishier.

This 1/4” poly-ethylene material compresses as the sill is bolted down, and prevents air from leaking in/out between wood and crete. Ostensibly. Problem is, even the best foundations are not perfectly flat, even, ahem, mine. Also treated wood, the most common sill plate material, shrinks over time while the sill-seal does not re-expand. What may have started as a pretty tight assembly, doesn’t stay that way. So we made lasagna.

Ω Sill Seal Assembly:

1 part 6 mil poly sheeting, 1 part copper termite shield, 2 parts butyl acoustical sealant, 1 part EPDM gasket.

This makes a double sealed assembly with any gaps covered by the redundancy, hopefully. The poly will get taped to the plywood sheathing on the outside of the framed walls which is our whole-house air barrier. Every seam, hole, knot, etc. will be caulked and sealed tight. This type of belt-and-suspenders approach is what we’re employing to achieve our goals in many aspects of the build. If we can’t do it perfect, we’ll do it twice. Or something.

Anyway, the basement walls are framed and the first floor trusses are in, just waiting on a subfloor.

Also, the concrete work is finally done and I started framing the garage this weekend. We’ll have our first roof in no time! If Fall doesn’t bluster it away first….

We have a warm-spell approaching, but I’ll try to make it back here when the mornings are frozen again. In the meantime I’ve put in 405.48 hours so far and this is what it looked like this morning.