Poly Dampcourse

A damp proof course ( dpc ) is a physical barrier inserted into the fabric of a building to stop water passing from one place to another. This can be on a horizontal plane, stopping water rising up from the ground by being sucked up by the dry masonry above, or vertically to stop water passing from the outside of a building, though the masonry, to the inside. Dpc's have taken many forms through the ages and one of the earliest forms was to use a layer of slate in the construction. Slate is still used but the less expensive plastic version ( below right ) is now more widely used.

Technical specification of dpc

Water vapour permeability
0.28 gm2 day-1
Bs3177

Water vapour transmission
733 mnsg-1


Water absorption
0.22%
Bs2782 : 430a

Resistance to leakage at joints
Pass
Moat 27 : 5.2.1

Tensile strength of joint
Unaged : 300 n
Heat aged : 290 n
Water soak : 257 n
Moat 27 : 5.2.2/3/4

Cold flex temperature
−60¡ãc
Bs2782 : 320a

Tensile strength
L : 12.9 nmm-2
T : 11.2 nmm-2
Bs2782 : 320a

Elongation at break
L : 415%
T : 582%
Bs2782 : 320a

Tear strength
L : 122 nmm-1
T : 96 nmm-1
Bba method

Low temperature flexibility
L : <−25
T : <−25
Moat 27 : 5.4.2

Dimensional stability
L : −2.0%
T : −0.3%
Moat 27 : 5.1.6

Mortar adhesion test
Pass
Cream method



Size available
110mm x 30 m/50m
150mm x 30 m/50m
230mm x 30 m/50m
300mm x 30 m/50m
380mm x 30 m/50m
450mm x 30 m/50m
600mm x 30m/50m
Special sizes made to order