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Fibreglass Door Cutouts as Sub-slab Insulation

Jeremiah_Sommer | Posted in Energy Efficiency and Durability on

Good day all,

I was chatting with an insulation subcontractor who was telling me that he recently detailed a basement sub-slab with one layer of recycled fibreglass door panels followed by 2” of closed cell spray foam. 

According to him, the 1.75” door panels are insulated to approx R11 with closed cell foam bringing his overall assembly to roughly R24. Other than the use of spray foam which we generally avoid, the idea of reusing waste material (door cutouts) seems appealing and the 2” of closed cell would provide a vapour and radon block.

Years ago, some builders in my market were reusing door panels from steel insulated doors, however it seems to have lost popularity and I haven’t see folks do this in recent years. Does anyone have experience with this assembly? My concern would be about compression and perhaps decay (if any) of the fibreglass skin on the panels. 

Any red flags to this assembly?

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