Materials
Vapor diffusion retarders are normally available as coatings or membranes. The membranes are technically flexible and thin materials, but sometime includes thicker sheet materials named as "structural" Vapor diffusion retarders. The vapor diffusion retarders varies from all kinds of materials and keep updating every day, some of them nowadays even combined the functions of other building materials.
Materials used as vapor retarders:
- Aluminum foil, 0.05 US perm (2.9 SI perm).
- Paper-backed aluminum.
- Polyethylene plastic sheet, 4 or 6 thou (0.10 or 0.15 mm), 0.03 US perm (1.7 SI perm).
- Advanced Polyethylene vapor retarders that pass the ASTM E 1745 standard tests ≤0.3 US perm (17 SI perm).
- Asphalt-coated kraft paper, often attached to one side of fiberglass batts, 0.40 US perm (22 SI perm).
- Metallized film
- Vapor retarder paints (for the air-tight drywall system, for retrofits where finished walls and ceilings will not be replaced, or for dry basements: can break down over time due to being chemically based).
- Extruded polystyrene or foil-faced foam board insulation.
- Exterior grade plywood, 0.70 US perm (40 SI perm).
- Most sheet type monolithic roofing membranes.
- Glass and metal sheets (such as in doors and windows).
Read more about this topic: Vapor Barrier
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