|
Material
|
Permeance
|
|
|
(kg / Ns) x 1E-11
|
|
|
|
|
Aluminium - foil
|
0.01 - 0.57
|
|
- foil backing plasterboard
|
0.025 - 0.50
|
|
|
|
|
Asphalt (1.1 kg/m²)
|
0.6
|
|
|
|
|
Breather Membrane
|
20
|
|
|
|
|
Building Paper (bitumen impregnated)
|
10
|
|
|
|
|
Felt - felt laid in bitumen
|
0.1
|
|
|
|
|
Kraft Paper - single
|
454
|
|
double
|
281
|
|
three-ply
|
200
|
|
four-ply
|
174
|
|
five ply
|
160
|
|
|
|
|
Paints - emulsion
|
200
|
|
- gloss
|
2.5 - 12.5
|
|
- vapour resistant
|
4
|
|
|
|
|
Polythene Film (0.06mm)
|
0.4
|
|
|
|
|
Polyethylene - 500 gauge (0.12mm)
|
0.286 - 0.500
|
|
- 1000 gauge (0.25mm)
|
0.167 - 0.250
|
|
|
|
|
Vinyl Wallpaper
|
10
|
Sources of data:
BSI 5250
J.Page and R.Lebens, Climate in the United Kingdom.
ASHRAE Guide
