Technical Concepts

A

AdhesionThe strength with which a membrane or coating bonds to the substrate, achieved by chemical bonding (with a primer), mechanical keying (a rough…

B

BitumenThe heavy fraction obtained by distilling crude oil; the base material of bituminous sheets and primers.

C

CohesionThe internal molecular bond strength that holds a material together.

D

Dew PointThe temperature at which air containing water vapour cools enough for the vapour to condense into liquid water.

E

ElastomerA polymer with high elongation that stretches and recovers.

H

HygroscopicityThe tendency of a material to absorb moisture from the air.

L

LapThe edge overlap where membrane rolls are joined over one another.

M

Mix RatioThe requirement to combine components A and B of a two-component system in the correct ratio by weight or volume.

O

Open TimeThe time after a primer or adhesive is applied during which it remains suitable for bonding the membrane.

P

PermeabilityA material's coefficient of permeability to water and water vapour.

P

Pot LifeThe time a mixed two-component material (epoxy, PU) remains workable.

R

Reactive ResinAn epoxy, polyurethane or acrylic material that cures through a chemical reaction.

R

Reinforcing CarrierThe internal layer that gives a membrane its mechanical strength.

S

Sd ValueA material's resistance to water vapour diffusion, expressed as an equivalent air-layer thickness in metres.

S

Surface TensionThe molecular attraction at the surface of a liquid.

T

Thermal BridgeA point of local heat loss where a metal, concrete or timber element interrupts the insulation layer.

W

W ClassThe water exposure classes (W1-E to W4-E) defined in the German standard DIN 18533 for building elements in contact with soil.