Attic insulation with foil back insulation boards

wizardman

Is it ok the lay 50mm or 60mm insulation boards across attic joists and put T&G flooring on top on it?

Is it safely spreading the weight? Between the joists is full with rockwool already. Its to store Christmas decorations etc.

I had planned on putting in 2x2 batons across the joists insulating between 2x2's and flooring on top. However just got thinking could I lay the insulation straight onto joists and floor on that.

Thanks

listermint

The boards will most likely crush and damage leaving the floor unlevel.

They are not designed to take that sort of crush force isolated to areas of their surface

Calahonda52

As above plus the following.

1. Am assuming the insulation is foil backed, which makes it impermeable to vapour, which runs the risk of condensation on the under side, depending on the thickness of the rockwool.
2. The rigid board will, in most cases, not be 100% in contact with the rock wool, leading in most cases, to a gap between both, allowing air to pass under it from the ventilated eaves, meaning the rigid insulation is useless.

wizardman

Thanks I'll just go with 2x2 batons and rockwool between and floor over