Building Materials - Vapour Resistance
Diffusion of vapor through building materials.
The vapor diffusion resistance through a material of a given thickness can be expressed as
Vr = t νr (1)
where
Vr = vapor resistance (Ns/kg)
t = thickness of material (m)
νr = vapor resistivity (Ns/(kg m))
Vapor resistivity of some common building materials
| Material | Vapor Resistivity (G Ns/(kg m)) |
|---|---|
| Brickwork | 45 - 70 |
| Concrete blocks, light weight | 15 - 150 |
| Render | 100 |
| Plaster, cement | 75 - 205 |
| Wood, pine | 45 - 1850 |
| Plywood | 150 - 2000 |
| Fiberboard | 15 - 375 |
| Hardboard | 230 - 1000 |
| Plasterboard | 30 - 60 |
| Straw-board, compressed | 45 - 70 |
| Wood-wool, slab | 15 - 40 |
| Polystyrene, expanded | 100 - 750 |
| Glass wool | 5 - 7 |
| Phenolic, closed cells | 150 - 750 |
| Membranes | |
| Gloss paint, average | 40 - 200 |
| Polyethylene sheet | 110 - 120 |
| Aluminum foil | 4000 |
