Monday, June 20, 2022

USA New Wall – example of Better wall system


Home Owners concerned with energy performance are few and far between in the mild climate of my local market. But a local project for a Youth Centre prrovided good cause to persue long term energy performance and reduced operating expenses, so that funds from the non-profit operator could go to the children's programs and not the utility.
Here you see the main wall stud cavity insulated, variable perm vapor control sheet in place, and horizontal furring for the utility cavity in place.

Unfortunately on this job we were not able to source the mineral wool insulation that is my preference due to pandemic related material shortages. We sufficed with partial recycled fiberglass batts by Knauf. 


As discussed in past posts, electrical boxes are 4x4x1.5 with reducer covers to fit conventional electrical devices and finish plates. In this case the builder's preference was metal boxes and armored wire due to the institutional nature of the project use, but as you can see there are analogous boxes and reducers in metal as well. Communications and Data low voltage wiring is run similarly in the utility cavity. Certainteed MemBrain variable permeability vapor control sheet seen here is the vapor control layer, and provides the primary air-tightness element in the wall.


Once the utility cavity is insulated following electrical rough-in the exterior walls are ready for drywall. Again lacking availability of mineral wool corresponding fiberglass batts were source, in this instance I believe it was Owens Corning acoustical batts in the 1.5"thickness.



Once drywalled, the electrical boxes will be indistinguishable from ordinary wall assemblies. Some early coordination with the Electrician and Inspector made inspections go smoothly, and gave the Electrician a clear understanding of the mission here. There were minimal penetrations through the vapor control sheet, allowing it to form the primary air tight element of the wall system. 

I hope this graphic documentation of a large scale installation is helpful for understanding real world applications of the USA New Wall assemblies. I'm always eager to see your applications of this in your work and would be happy to share them here. 

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