Enclosing and Strapping a Passive House Roof

The completed structure before roof membrane and strapping. The trusses were set with a crane. In this view, you can see the diagonal 2x4 bracing for the truss system, and the metal spacers used to stiffen the top chords of the trusses.

A view of the truss system from below shows how the raised heels of the trusses butt to the OSB skin of the second-floor wall panels. Strips of membrane hanging down from the wall plate will be used to tie the air barrier of the occupied space (created with smart vapor-control fabric), into the wall system air barrier (formed by taped OSB sheathing over the 2x wall frame). In this view you can also see the metal bridging used to space and stiffen the trusses, as well as the diagonal 2x4 truss bracing.

A closer view of the raised heel detail on the trusses shows the 2x4 bracing applied to the inboard side of the truss tail, and the wall system’s OSB skin (which extends up to cover the truss heels).

Another view of the diagonal bracing applied to the truss web chords.

A view of the roof eave juncture shows the first course of Pro Clima Solitex Mento Plus applied to the roof framing, and taped to the Solitex Mento Plus on the wall panels to create a continuous weather-resistive barrier for both wall and roof. The wall panels’ strapping was applied in the shop; similar strapping for the roof will now be applied in the field.

This view shows the first vertical strapping pieces applied to the roof truss top chords through the Solitex Mento membrane.

A carpenter applies horizontal 2x4 strapping to the roof over the 1x3 vertical strapping. This creates a space allowing air movement in all directions. Solitex Mento membrane is air-tight but highly vapor-open. The insulated space beneath the membrane will be able to dry into the vented air space created by the strapping. The horizontal 2x4 strapping will provide nailing for the metal roof, to be installed next.

Using the lower courses of 2x4 cross-strapping for footing, a carpenter extends the vertical 1x3 strapping farther up the roof, working towards the peak.

Using a spacer block, a carpenter applies more courses of 2x4 cross-strapping to the roof.

This view of the roof ridge shows the completed strapping system extended all the way to the roof peak.

A view from the ground shows the completed roof strapping system.

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