Watertight Wall Underlay

Watertight Wall Underlay is a synthetic wall underlay for use as a flexible wall underlay under wall claddings on timber and steel-framed buildings. The product consists of a micro-porous water-resistant polypropylene film laminated between two layers of spun-bonded polypropylene and is coloured grey.

Flexible wall underlay

Watertight Wall Underlay has been appraised for use as a flexible wall underlay for timber and steel-framed buildings within the following scope:

• The scope limitations of NZBC Acceptable Solution E2/AS1 paragraph 1.1 with regards to building height and floor plan area.
• With direct-fixed absorbent and non-absorbent wall claddings.
• With absorbent and non-absorbent wall claddings installed over an 18 mm minimum drained cavity.
• With masonry veneer in accordance with NZBC Acceptable Solution E2/AS1 for timber-framed buildings or to a specific design for steel-framed buildings.
• Situated in NZS 3604 wind zones up to and including very high.

Use over rigid wall underlay

Watertight Wall Underlay has been appraised for use as a flexible wall underlay over rigid wall underlays on timber and steel-framed buildings within the following scope:

• The scope limitations of NZBC Acceptable Solution E2/AS1 paragraph 1.1 with regards to building height and floor plan area.
• With absorbent and non-absorbent wall claddings installed over an 18 mm minimum drained cavity.
• With masonry veneer in accordance with NZBC Acceptable Solution E2/AS1 for timber-framed buildings or to a specific design for steel-framed buildings.
• Situated in NZS 3604 wind zones up to and including extra high.

Specific design

Watertight Wall Underlay has also been appraised for use on buildings subject to specific weathertightness design. Building designers are responsible for the building design and for the incorporation of Watertight Wall Underlay into their design in accordance with the declared properties and the instructions of Techno Wrapping Systems Ltd.

Techno Insulation. Brochure Version No.1. Roof Underlay, November 2017

Always refer to the Appraisal in full and the technical literature.