Do I need to use membranes when installing PIR below a concrete slab or screed?

Ensure that the PIR insulation boards are laid above the damp proof membrane (DPM). The foil facings of PIR insulation boards may be damaged by wet screed or wet concrete, allowing gas to escape that may weaken the floor topping, so its recommended that membrane is used for protection over the PIR insulation boards once they have been laid & prior to the screed or concrete topping being poured.

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