Walls and insulation

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Sustainability goals for our wall system

Because we were designing a Super Insulated Building Envelope, our wall system design was extremely important. Our goals included:

  • Minimize thermal bridging
  • Reduce energy use of existing building by at least 70%.
  • Use envelope and insulation materials that do not harm building occupants or the environment.
  • Use envelope and insulation materials that are existing, recycled, and/or local materials wherever possible.

Wall design

  • Historic side

Built second wall inside the brick/block walls to accommodate super insulation while preserving historic appearance and keep block from entering waste stream. Modeled wall system with WUFI software to determine how best to achieve high R-value and also deal with moisture within our super insulated wall assembly design

Historic brick/block layer 8" thick
Weep holes at base of wall to drain moisture from behind masonry layer
Drainage plane 1" thick
This air layer helps control thermal bridging by separating the inner wall from the outer wall
Also helps control moisture build up in the wall by providing a path for condensation or rain water to run down to weep holes
Firring blocks 1" thick
Controls thermal bridging by holding stud wall away from drainage plane behind masonry
Polyiso rigid foam board 2" thick, 2 layers with staggered seams (total of 4" thick)
Cellulose blown-in insulation (and wood studs) 5" thick
Absorbs and dissipates moisture like a living organism
Contains fire retardant and mold inhibitors
Gypsum wallboard 1" thick, 1/2" reused from existing, 1/2" new material
Total thermal resistance for the walls is R-42
Total wall thickness is 18.5"

The importance of insulation

Suppliers and materials

See also

from Super Insulated Building Envelope