I'm totally aware of the arguments for and against stud cavity air returns so I don't need opinions on that, but I do need an idea of the best material for lining the outside of the stud cavity with. Is sheet metal the only option or is there something else you can use?
1 Answer
Thermopan and similar material is a good alternative to sheet metal joist lining. It seals better and doesn't tin can like metal joist lining.
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(https://i.sstatic.net/Q4Yw1.jpg)
It's ba fire rated cardboard but it works well.