12 Waterproofing of expansion joints and connection to other types of roofing

12.1 Waterproofing of expansion joints

Waterproofing of type I joints (DIN 18531):
Over the joint, the roof waterproofing can be laid flat in a single ply. The waterproofing over the joint must be supported by applying suitable measures like support plates so as to prevent the covering from sinking into the joint gap.

Roof waterproofing made of bonded EVALASTIC® waterproofing membranes may also be installed flat over joints moving up to 5 mm. At least 0.2 m wide sliding strips must be placed under the waterproofing.

With loose laid EVALASTIC® waterproofing membranes the roof waterproofing can be installed over joints with a expansion of up to 10 mm, provided the membranes are supported in the joint area.

Waterproofing of type II joints (DIN 18531):
Depending on the extent and the frequency of joint expansions, the type of waterproofing is to be decided upon individually, e. g. by installing loops of suitable waterproofing materials with EVALASTIC® membranes and round profiles (for expansions up to 25 mm and a joint width up to 30 mm).

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Type II joint waterproofing may be raised over the waterproofing level, e. g. by placing wedge-shaped insulation elements or with cants. Roof areas separated by raised formations must have independent drainage.

If expansion joints in the flashing area to kerbs (e. g. annexes) are inevitable, appropriate constructive measures like installation of support plates (min. 1.5 mm) are required.

12.2 Installation of a flashing to roof waterproofing made of different material

Roof waterproofing consisting of EVALASTIC® waterproofing membranes are compatible with all standard waterproofing materials. It is not possible, however, to ensure permanent waterproof connection to these materials (except for some liquid plastics 34). Professional flashings to roof waterproofing which are made of different material can be installed only along high points of the slope (arris).+

water drainage level by approx. 15 cm

Roof waterproofing which cannot be connected so as to be water tight should be raised above the water drainage level by approx. 15 cm, jointly fastened mechanically and covered so as to be watertight.


34 Producers of liquid sealants on request.