Great project! It is very interesting to follow your field notes and watch the progress of this complex house. Thanks for sharing!

What will you use to seal the gaps between the OSB?

The sheathing is not our air barrier. A fluid applied air barrier will be applied over the OSB, sealing all gaps and holes.

Jay, As Cory mentioned, we are utilizing a seamless liquid applied air-barrier system that is applied directly to the sheathing. We have tried several liquid products but, the Wet-Flash system is our favorite. The plywood seams will be treated with their
pink Joint and Seam sealant, the ROs will be covered with red Fast-Flash, and the liquid air-barrier/WRB is a roll on product called Cat-5. The cool thing about this system is that it can be applied on damp substrates and is very vapor permeable. The product
was developed locally by Building Envelope Innovations, so it was designed to be compatible with our wet weather. More info here: http://www.prosoco.com/AirBarriers When we tape the seams we typically use SIGA tape from Small Planet Workshop or 3M 8067 All
Weather Flashing Tape.

How do you protect your EPS foam from any petroleum products that are in the soil or accidently get in the soil in the future? Won't petroleum eat up the EPS and compromise the foundation?

Jay, Good question. The project is located near the top of the watershed in a rural location. Contamination from petroleum is not likely. If we were building on a brownfield site with the potential for petroleum contamination, we would have no choice but
to install the EPS foam over a chemical resistant vapor barrier or other appropriate geotextile system. I do not think a traditional polyethylene vapor barrier would be up to the task of protecting the EPS from groundwater or soil contaminated with petroleum
hydrocarbons or solvents. -Skylar

Thanks for the response Skylar I think most fuel and oil containers are made from polyethylene. My reason for asking is I live in an area that was developed in the 1940's and 1950's with most homes using oil for heat. As I was buying my house in 2009,
I actively went looking for oil tank and had the tank located even though the house was switched over to natural gas in 1980. After the tank was removed, contamination was found underneath it but just below the threshhold for manditory state ecology clean
up. So the contaminated soil is still there about 5 feet underground. I am planning to protect my future passive house slab on grade foundation by using three layers of 15 to 20 mil polyethylene. One layer on the bottom of the excavation, one layer on the
top of the fill and one layer on the top of the EPS Foam. All of this will be seamless pieces and brough up above ground level. I can't imaging how you would fix a sink foundation caused by the EPS foam eroding from petroleum contamination. I enjoy read your
blog. Jay

You should check out Liquid Boot, a product made specifically for sealing over contaminated soil. http://www.radata.com/pdfs/CETCO%20Liquid%20Boot%20Brochure.pdf

Great to see such care for detail continues in the trade. Enjoy

Hello ! Can you please explain the function of the compressible felt, or link to an explaination online. If we cannot get this felt, what are simpler options ? Viveik

Viveik, I just spoke with project lead Scott Gunter about the compressible felt and he referred me to a great passage in Lstiburek's Builder's Guide to a Mixed Climate that states, "Concrete cracks. Concrete has always cracked. Concrete will always crack."
Lstiburek goes on to explain the importance of using control joints to encourage cracks to occur in a more controlled and predictable manner. The compressible felt gives the concrete some much needed wiggle room and helps bring order to the chaos of cracking.
As for sourcing the felt, in Oregon it is readily available at masonry supply houses. If felt isn't available in your area there are foam, cork, and rubber alternatives that will serve the same purpose.

Zack, Where are you getting the heat pump clothes dryer? Thanks! John

Hi John, Great to hear from you! I spoke with the project team about your question, and essentially the answer is "we're still working on it". We've got time yet to source the appliances for the project, so we're waiting to see what becomes available in
the US in coming months. We might also explore purchasing from Europe... though of course we'd like to avoid the $ and carbon associated with that. Zack