Home Designing Service, Ltd

Residential Design Specialists serving Connecticut and beyond

IRC 2009 Revision: Air Sealing and You

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So it’s that time again. IRC revision time. Woooo! Break out the booze and the confetti, it’s gonna be a party. And, by “booze,” I mean air seals and, by “confetti,” I mean wind bracing. Of course. What else would I have meant?

You probably know what the IRC is, but maybe you don’t. It stands for International Residential Code, and it governs how one- and two-family houses should be put together. It basically makes sure designers and contractors are keeping up with current practices and the people who employ them are getting the best for their buck. Every few years, things get changed, everyone has a couple years to freak out and pretend there’s absolutely no way they can build a house under the tyrannical new guidelines. Then the changes go into effect, everyone settles down and it’s repeated a few years down the road. We builders are an exciting lot.

But honestly, as crazy as it can get when stuff gets technically more difficult, by the time a change is made, it’s often after that change has become common practice anyway and the technology is already there to facilitate an easy transition. It also shakes off those amateur crazies who are more interested in swindling customers than making a functional house. We here at Home Designing Service are not too keen on swindling, so we’re going to go ahead and talk about some of these IRC changes.

One of the biggies, and the subject of today’s post revolves around air sealing. Arguably more important than insulation, air sealing is a huge hurdle to jump when finishing off a house. Making sure there aren’t huge gaping holes in the walls is one thing, but keeping the air out from tiny cracks around windows and doors, or from pouring into the attic and then into the house, those are entirely different matters. For the IRC 2009, the magic number you’re looking for is 7.

End of blog. Everyone go home.

Seriously, though. Air sealing is more than drywall or the vapor barrier. It’s more than making sure the windows are in and closed. We’re talking more than fiberglass batts for insulation. And air sealing should be tested at several points during the construction of the house, because, basically, once the insulation’s in, doing a proper sealing becomes much more difficult. For Energy Star ratings, there’s a LEED checklist that needs to be gone through before drywall is even up. This gives builders a chance to find leaks before fixing them requires that a wall be ripped into. They can go around and do targeted air sealing on pipes and wires, corners where stuff might not be entirely lined up, etc. Then when everything’s mostly together, they do a blower door test. And they hope for that 7 I mentioned earlier.

So, this blower door. It’s exactly what it sounds like. It’s a door. With a blower in it. It depressurizes your house and then, using the kind of math where there are almost no numbers and it’s all funny symbols and letters, they determine how many times the fan and suction of the vacuum was able to replace the atmosphere within the house in an hour. Seven ACH, or air changes per hour, is the max. It’s also kind of a big number. Quality builders who trip and accidentally make a house are going to hit a 5, a 3 if they actually try a little. California’s code requires a 3. Energy Star Canada wants a 2-2.5. And then there’s PassivHaus. PassivHaus is, if the name didn’t tip you off, primarily a Swedish and German company, although they’ve been seeing a recent popularity surge internationally. PassivHaus requires a 0.6. Which basically means when you turn the blower door on, your house crushes like a tin can because there are no leaks. I’m pretty sure they use ancient technology dredged up from lost Atlantis to make this possible.

Joking aside, air sealing covers a wide range of needs. Want to stay warmer and have less/no drafts? Want to save money? Want to reduce your carbon foot print, use less energy and help save the planet? I mean, we’re not exactly in “For just 50 cents a day, you can save a child in Africa” territory, but we’re pretty close. We at Home Designing Service know our stuff. Give us a call, come in, email, whatever you like, and there’ll be a specialist here to go over all your air sealing and non-air sealing needs. We might even let you flip the switch on the blower door.


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