conventional practice nowadays, and most contractors have gotten over their fear that the fastening will fail. We know that the compression of the fasteners can provide enough friction to overcome the force of gravity. Different insulations have some performance aspects to consider, such as how water, air, and vapor interact. This is important to learn because the WRB must be installed differently with, say, mineral wool boards than with wood fiberboard. It is possible that rigid wood fiberboard could be the gamechanger in reducing embodied carbon in buildings. Some of the products can act as the WRB, thereby reducing labor costs, and some provide shear support – thereby eliminating the need for sheathing in some seismic zones8. The only current producers are in Canada and Europe, but GoLab will come online in Maine in the near future9. • Interior insulation can be increased by widening the framing, either by using 2x8 instead of 2x6 structural walls or adding an extra wythe of minimal 2x3 or 2x4 framing. Often spray-foam loyal contractors will agree that the extra cost of 2x8 framing lumber will offset the cost the stem wall because of wicking. • EPS, mineral wool, and foam glass (not on the chart of insulations) are three relatively easy options for of foam insulation, so they can’t argue that “thicker walls are more expensive.” The R-value of a 2x8 wall with cellulose or batts is still not quite as high as the R-value of a 2x6 wall with spray foam. Still, most contractors will advocate for flash and batt over filling the entire cavity with foam, so even if they build a 2x8 wall but ultimately go with their preference of flash and batt, the harm of foam is still reduced. If they end up filling the 2x8 cavity, well, then, you did more harm, but you also will have learned a lesson (personal experience) – work with contractors you trust and clients who trust you. A double-stud wall is a can of worms in terms of options for thickness and insulation options. It’s less conventional and more challenging to frame. But because of the options it can be the right choice if you have a client who is willing to push the sustainability envelope with an alternative insulation such as straw bales10. Panelization helps us to conventionalize and control the worms in the can. When we start talking panels with contractors and clients, people care less about what is inside the panel and more about how much time they can save in a short building season. This can be a great strategy for bringing everyone over to your side. There is risk with panelization and there is more upfront investment. The panel company must be reputable and the shipping should not overwhelm the savings. Some reputable American and Canadian panel companies include: • Tectoniks: bensonwood.com/tektoniks • Collective Carpentry: collectivecarpentry.com • Ecocore: ecocor.us/enclosure-systems-2 • New Frameworks Gryphon Panels: Ecococon https://ecococon.eu are excellent European panel companies looking for U.S. projects so they can begin to manufacture in the states. Foundations are challenging. Water and biodegradable materials do not mix and this is the most vulnerable part of the building. It is hard to get around using a higher-energy insulation while also preventing mold and rot. You must first decide if the insulation should be interior or exterior and to how much moisture it will be exposed. Credit FineHomebuilding PC: Cairn Collaborative — continued on page 42 41
RkJQdWJsaXNoZXIy ODQxMjUw