Planning and construction guidelines

The difference between rainproof and waterproof roof linings

Roof linings serve as an independent sealing layer underneath the actual roof covering. They are installed as an additional measure to ensure either rainproofing or even waterproofing of covered roof structures if the roof pitch is less than the standard roof pitch. Roof linings are installed on a base with sufficient load-bearing capacity, e.g. on decking consisting of solid wood or wood-based panels.
The requirements and specialist regulations that apply to roof linings are published by the Central Association of the German Roofing Trade (ZVDH).
Rainproof or waterproof roof linings are necessary if the roof pitch of the roof covering is less than the standard roof pitch of 8° to 12°. A rainproof roof lining (Class 2) is installed when a maximum of one additional increased requirement applies. If there is more than one increased requirement, a waterproof roof lining (Class 1) is necessary.
One fundamental difference between rainproof and waterproof roof linings is the arrangement of the the counter battens. On rainproof roof linings, the counter battens are installed above the rainproof underlay, see Fig. 1. Any precipitation water that enters around the counter battens must also be drained off in a reliable manner. In the SOLITEX WELDANO system, this is achieved by installing TESCON NAIDECK nail sealing tape beneath the counter battens.

Fig. 1: Rainproof roof lining: Counter batten with nail sealing tape on seal membrane (CH: standard design for exceptional loads)

In the case of waterproof roof linings, the counter battens are integrated into the sealing, e.g. by guiding the surface roof lining membrane over the counter battens. With regard to installation, however, it is often easier to first install the membrane flat on the decking, and then to fasten the counter battens and heat-weld a SOLITEX WELDANO-S sealing strip around them, see Fig. 2.
Important: The counter battens must be dry and chamfered on their upper side (≥ 3 mm (1/8")) when they are installed. Ideally, kiln-dried battens should be used.
For waterproof roof linings, the number of feed-throughs should be the minimum necessary. These must then be sealed above the roof lining membrane and stuck or welded to the penetrating component in a waterproof manner in accordance with the regulations.
Openings in the ridge area are not permitted on waterproof roof linings. In contrast, openings in the ridge area can be implemented with an appropriate design structure on rainproof roof linings. Rainproof and waterproof roof linings can be implemented in a practical, reliable manner using the SOLITEX WELDANO system.

Fig. 2: Waterproof roof lining: Counter batten integrated into the sealing layer (CH: possible additional measure)

Classification according to ZVDH

Designation as per ZVDH Type of counter batten inclusion Formation of seams and joints Class
Rainproof roof lining Installed flat beneath the counter batten and sealed with TESCON NAIDECK nail sealing tape Homogeneously heat-welded using the WELDANO TURGA system solvent welding agent or a hot air gun 2
Waterproof roof lining Guided over the counter batten or covered with SOLITEX WELDANO-S and heat-welded Homogeneously heat-welded using the WELDANO TURGA system solvent welding agent or a hot air gun 1

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