Geoff_Briggs

The final pricing came in too high, partly because the clients added stuff, partly because the contractor, who we have not worked with before, “misunderestimated” the complexity of the envelope. To bring things back in line the clients chose, against our strenuous objection, to abandon Passive House and build to the latest (soon to be adopted) energy code. Less insulation, cheaper windows, modest air sealing, no rainscreen. An exercise in de-value engineering if there ever was one.

They could have easily cut the budget by reducing the volume of the house, which is excessive. We presented a number of more right-sized options to them over the course of preliminary design only to see our plans suffer size inflation with a couple feet added here, a couple more there, until you end up with 5K sq ft for two people.

All in all a downgrade in performance and commitment.

We recently designed a Passive House with a rainscreen over 4" of rigid foam over 2x6 framing with dense pack cellulose. We designated the exterior sheathing as the air barrier so the envelope could be tested, accessed, and fixed before any insulation was installed. Given the fact that this system would keep inside of the sheathing warm (the project is in Western Washington) I was very comfortable specifying this assembly. Add the extremely stringent Passive House air sealing requirements and continuous mechanical ventilation and you've got a bomber wall.

Unfortunately the project was "downgraded" to standard 2x6 construction following the 2009 WA State Energy Code. Now I'm not so confident.

Even without the extreme airtightness I'd be more comfortable with the exterior insulation assuming the wall can dry. Sure it has to be detailed well, but that's always the case if you don't want trouble from bulk water.

Taunton’s books are almost always approachable, easy to read and well organized. Many have become go-to references. Looks like I may be adding this one to that list.