Exterior Insulation Thickness and Vapor Permeance
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Is there a good resource online to understand how the thickness of exterior insulation (or any material, for that matter) affects the vapor permeance of an assembly?
I hear things like mineral wool and wood fiberboard touted as more vapor permeable than foam, but it seems like if the insulation is thick enough, it approaches a low enough permeance that the differences are not as significant.
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Replies
Andyfrog,
As usual Martin explains this far better than I could:
https://www.greenbuildingadvisor.com/article/all-about-vapor-diffusion
thanks!