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 (N s/kg)

t = thickness of material (m)

νr = vapor resistivity (N s/(kg m))

Vapor resistivity of some common building materials

MaterialVapor Resistivity
(G N s/(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

Related Topics

  • Insulation - Heat transfer and heat loss from buildings and technical applications - heat transfer coefficients and insulation methods and to reduce energy consumption

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