One of the key principles in Passive House construction is to have well insulated walls, roof and floors that are also air tight. We looked at a couple of different options including building on-site or going with prefabricated panels. We decided to go prefabbecause it will shorten the construction schedule by a couple of months and the quality of construction will be better with them built inside a factory. There are two different approaches to pre-fab. BC Passive House in Pemberton makes a 2×6 framed wood wall with cellulose insulation and CutMyTimber in Portland makes Cross-laminated timber-CLT wall, floor and roof assemblies with a Roxul mineral wool insulated that goes on the outside. Cross–laminated timber (CLT) is a wood panel typically consisting of three or five layers of dimension lumber oriented at right angles to one another and then glued to form structural panels with exceptional strength, dimensional stability, and rigidity. In the picture below the 4 1/8″ dimension is the CLT wall panel and the 6″ dimension is the Roxul insulation, the 8″ dimension is the concrete footing and the 3 1/2″ dimension is an interior wall cavity for running utilities. We are using the CLT panels with Roxul because of the strength, insulating value and the manufacturer could meet our construction schedule. CutMyTimber is just finishing up the shop drawings and the panels should be finished by Christmas for installation with a crane in January.