Insulation under brick veneer installed over steel framing
kgva
| Posted in Green Building Techniques on
What is the best way to insulate a steel framed wall which will be brick veneered?
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Continuous insulation between the steel studs and the brick is critical to getting any thermal performance out of it.
Steel is about 375x as thermally conductive as wood, which takes a huge toll on the performance of cavity-fill. After thermal bridging a 2x4 wall with studs 16" o.c. with R15 rock wool comes in at about R10 after thermal bridging, but the same wall stud-for-stud with steel framing comes in a bit under R7. With R13s it's under R6.
http://web.ornl.gov/sci/roofs+walls/research/detailed_papers/thermal_frame/
Raymond,
Just so there is no misunderstanding: when Dana wrote "between the steel studs," he didn't mean that the insulation should be installed in the stud bays. He meant that you need to install a continuous layer of rigid foam insulation, entirely on the exterior side of the steel framing.
If you are aiming for R-20 walls, you will need 5 inches of EPS, 4 inches of XPS, or about 3 inches of polyiso. More is better.