A Best Practices Manual That Can Help You with the Details
Hammer & Hand, a construction company from the Pacific Northwest, is sharing its best practices with everyone
When I was building a home in 2001, I came up against a gazillion little things that I needed guidance on. I'd never built anything larger than a bookcase, so new home construction was quite a big step.
I bought books, scoured the web, and tried to get as much info out of Southface as I could, but I still couldn't find everything I needed. As a result, I made mistakes because, as you know, the devil is in the details.
Builders now have a lot more information available online. Of course, there’s Green Building Advisor. (You’re soaking in it!) If you’re a GBA Pro you get access to a great library of details and more. And it doesn’t take a lot of work for a researching builder to end up at the web site of Building Science Corporation. Lstiburek and company provide a great service to us all by making so much information freely available. Ibacos, another Building America Partner, has likewise put a lot of great info on the web, mostly through the Building America Solution Center.
I just learned of a really nice addition to this online resource a couple of weeks ago. Hammer & Hand is a construction company in Portland and Seattle that focuses on high performance buildings, particularly Passive HouseA residential building construction standard requiring very low levels of air leakage, very high levels of insulation, and windows with a very low U-factor. Developed in the early 1990s by Bo Adamson and Wolfgang Feist, the standard is now promoted by the Passivhaus Institut in Darmstadt, Germany. To meet the standard, a home must have an infiltration rate no greater than 0.60 AC/H @ 50 pascals, a maximum annual heating energy use of 15 kWh per square meter (4,755 Btu per square foot), a maximum annual cooling energy use of 15 kWh per square meter (1.39 kWh per square foot), and maximum source energy use for all purposes of 120 kWh per square meter (11.1 kWh per square foot). The standard recommends, but does not require, a maximum design heating load of 10 W per square meter and windows with a maximum U-factor of 0.14. The Passivhaus standard was developed for buildings in central and northern Europe; efforts are underway to clarify the best techniques to achieve the standard for buildings in hot climates.. I've gotten to know several of them from the Passive House conferences I've attended over the past few years, and they're a really impressive group. Zack Semke e-mailed me recently to tell me about their Best Practices Manual.
From conditioned crawl spaces to kick-out flashing...
The diagram above is from the manual, and it's from the chapter on one of my favorite topics: crawl spaces. This is their diagram for detailing an encapsulated crawl space in new construction. They also show how to encapsulate a crawl space in an existing home and how to keep the building enclosure at the floor above the crawl space — along with recommending when that's OK.
The manual doesn't have everything you might look for — yet. They're still working on it and will release more details as they are developed. The manual is also biased toward their climate. Their recommendation for ventilating an encapsulated crawl space is to put in an exhaust system and ideally to use an HRV(HRV). Balanced ventilation system in which most of the heat from outgoing exhaust air is transferred to incoming fresh air via an air-to-air heat exchanger; a similar device, an energy-recovery ventilator, also transfers water vapor. HRVs recover 50% to 80% of the heat in exhausted air. In hot climates, the function is reversed so that the cooler inside air reduces the temperature of the incoming hot air. . That might work in the Pacific Northwest, where the outdoor air is cool and dry, but it's not ideal for humid climates. (Yes, I really did say the Northwest is cool and dry. It's a psychrometrics thing.) If you want more on that topic, I've written up a more complete discussion of ways to deal with crawl space air.
The chapters in the manual are:
- Sealant Joints (from which Image #2 below is taken)
- Windows & Doors
- Rain Screens
- Wall Penetrations
The spirit of cooperation
It's really great stuff! And not only that, but they are sharing this freely with anyone and everyone through their website. They've put the Creative Commons license (that's the CC on the images above) on all of it, so you're free to use it pretty much how you choose as long as you follow their (light) restrictions:
Hammer & Hand’s Best Practices Manual is covered by a Creative Commons license that allows for redistribution, commercial and non-commercial, as long as content is passed along unchanged and in whole, with credit to Hammer & Hand. If any piece is shared online, it is required to credit Hammer & Hand and include a link to the relevant source page.
Sam Hagerman, a co-owner of Hammer & Hand, wrote: "We look forward to our role as participants in the economy of knowledge around all these concepts. Our efforts are offered in the spirit of cooperation, collaboration, and the greater good."
Thank you, Hammer & Hand, for helping us fight the devil in those details!
- Hammer & Hand
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