Polyethylene or reinforced sheet, commonly 10 to 15 mil and meeting ASTM E1745, laid with lapped and taped seams and sealed around every penetration. Placed directly under slabs that will receive wood, vinyl, tile or other moisture-sensitive flooring, it keeps vapor from wrecking the finish floor. The tradeoff is that bleed water can only leave upward, which stretches finishing time and adds to curling.
Vapor retarder's got three holes by the plumbing, tape them before the rod busters start setting chairs on it.
Field crews call it vapor barrier or Visqueen no matter which term the spec uses.
Also heard as
- vapor barrier
- Visqueen
- poly
- moisture barrier
Related terms
Bleed water
Water that rises to the surface of fresh concrete as the heavier solids settle.
Curling
Upward warping of slab edges and corners, caused by the top drying and shrinking faster than the bottom.
Rat slab
A thin layer of lean concrete over dirt that gives a clean working surface or seals a crawlspace floor.
Chair
A wire or plastic stand that holds rebar or mesh at the right height inside the form.