Air-sealing 101 for new home builders who have failed their blower door tests

Looking for web links to good sources of info on air sealing, stuff that would be helpful for builders who need to go through their almost-finished home and tighten it up. I do a lot of testing of new homes, and in the past several years most people have passed without a problem. Right now, I have three different guys who are not meeting the standard and are faced with the gory task of trying to air-seal brand new homes. I honestly do not want the air-sealing work at all, and I don't even want the consulting work to try to help them get to the finish line. I want to point them to resources that they can read and digest and then go git 'er done... call me when you think you're ready for a re-test. I know there's lots of stuff out there, and hoping that someone here has pinpointed the best of it. Thank you in advance.

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In my opinion, it is often too late to tighten up near end of construction, but something like may help them.

No idea on durability of system and what VOC's it adds to interior.  

Energy Star and Building America have some great resources for builders who want to learn how to air seal and reduce thermal bridging. I don't have any specific links for Building America, but here's a link to their Guides search engine. This link is already filterd by 'new construction' and 'thermal enclosure'. You can add additional filters for climate zone, etc. There's also a search engine for videos (see left side menu).

The best single resource I've seen is the pictorial guide to the EnergyStar v3 Thermal Enclosure System Rater Checklist.

David Butler nailed it for the best all around resource - I have quite a few on my site also starting with My Take: How hard is it to hit the IECC Air Leakage Targets?

Beyond that where are the leaks coming in at (it is just like an older home) Two easy misses is around doors & the attic hatches where I have seen anywhere from 50 to 400 cfm on just one of those

BTW - crawl space, SOG? attic with recessed lights, where are ducts...

As for Sean Wiens piece - looks great if done pre drywall but definitely not after finishes have gone in

@Sean Lintow wrote:
> As for Sean Wiens piece - looks great if done pre drywall...

I was curious about that too. One of the photos shows house with drywall taped & mudded. Seems like an aerosol sealant would leave a slight residue or build-up around the leakage paths, creating a lot of prep an/or clean-up work.

The article mentions having to clean up joints between window sashes and frames after application. Wouldn't it be easier to tape those off? The drywall picture does show tape between upper & lower sash.

But what about the glass itself? It seems like a portion of the sealant would settle on the glass, as well as floors, walls and every other surfaces. I don't see how 100% would remain airborne until it eventually reaches the cracks under blower door pressure.

I would consider using this on my own new home, soon to break ground. But I doubt anyone in my area (SE AZ, Tucson) has rig, Ditto in David Meiland's area (San Juan Islands, NW Washington state).

Yeah I finally got a chance to read it & while they say it can be done with finishes installed I wouldn't chance it. Made by same company that does ducts - activates by lower humidity & temperatures outdoors to turn to gel... They mentioned that if they forget to seal off exhaust fans that they are completely sealed - hate to see where some of this might start forming, gaps in wood flooring, outlet covers, lights

Funny part in there is where some open cell guys were saying they accidentally would hit .8 or accidently hitting 2 ACH - guess none of them is testing there work

I can only see this being done at framing once everything is dried in with maybe the drywall cap in place though up here were conduit rules the drywall cap might be pushing it. I would definitely consider using it if building like Steve Baczek with zipwall fully up before windows

We have a new  system that air seals stick-framing by over 80% according to New York State Energy Agency. In a side-by-side identical test we scored 30.4% better than comprehensive caulking method from the interior. Builders that are required to meet new air targets can save thousands when code compliance is achieved with fiberglass insulation as an alternative to spray foam.    

Here is the link

The three things I would do first is to try to find any big holes - returns missing pans in the attic and stuff like that.  Use a scanner to check interior cavities. Second, I would seal the wall/ceiling joints in the attic - we have found an already tight house can be 10% tighter after this - best to do your testing before attic insulation is blown. Third, I would spend time sealing at the basement band.

If they are small houses under 1200 ft2, you could be suffering from the small house penalty.  We have had luck showing an inspector that a given house has a low ERI/HERS rating and sealing the house from 3.3 to 3.0 would save just a few dollars a year where the builder has already saved hundreds by building above code.

I speak with hundreds of builders on the topic of air-sealing.

 I ask them this simple question, "are you sealing from the inside (post frame) trying to stop conditioned air from leaving the space or stop moisture latent air from entering the space"? Most say both, so if the latter is true than they have to admit that moist ambient air intrusion has already diminished their insulation value. You have to do both for insulation to do it's intended job.

Yeah - these!  At EcoWorks, we used to take things like the BSC document and just get builders to print them out, post them on site, give them to their subs (these and diagrams from the EEBA guides). They're so clear and straightforward, but we need to get them in front of builders and subs to keep them in mind.

A little semi-amusing follow-up on this one. I ended up loaning a door set-up to each one of these guys so they could get some personal experience with guided air-sealing. They all made it work. In one case, it was a very seasoned custom building crew who took it to heart, got in the attic and crawl space and made a major improvement. At the other end of the spectrum was a guy who's a new-ish spec builder and I'm not sure he'd ever been in a crawl space before... but he has now. They all got under 5 ACH50, which is our (lax) standard here. They all now understand that they have to supervise their subs very closely whenever they see a sawzall or a hole hawg in use, and they all know they can't trust their insulator even if the contract says "air sealing" on it. They also need to start thinking about air sealing as soon as the first sheet of plywood gets delivered to the job, if not sooner.


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