Core TradesQuestion 208 of 700
A vapor retarder placed directly under a concrete slab-on-ground in habitable space is commonly required to be polyethylene sheeting with a MINIMUM thickness of:
a.4 mil
b.6 mil
c.10 mil
d.15 mil
Explanation
A minimum 6-mil polyethylene vapor retarder is commonly required beneath interior slabs to limit moisture migration into the floor. 4 mil is thinner than the standard minimum, while 10 and 15 mil are heavier products sometimes specified but above the basic requirement.
Law Reference: 2025 CA Residential Code, R506 (Concrete Floors on Ground)Practice all 700 questions free — no signup required.
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