Description

Hydra Classic 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 polypropylene film laminated between two layers of non-woven polypropylene and is coloured white.

Scope

Flexible Wall Underlay

1. Hydra Classic Wall Underlay has been appraised for use as a flexible wall underlay for buildings within the following scope:

• the scope limitations of NZBC Acceptable Solution E2/AS1 for timber-framed buildings; or,
• the scope limitations of NASH Building Envelope Solutions for steel-framed buildings; and,
• with direct-fixed absorbent and non-absorbent wall claddings; or,
• with absorbent and non-absorbent wall claddings installed over an 18 mm minimum drained cavity; or,
• with masonry veneer in accordance with NZBC Acceptable Solution E2/AS1 for timber-framed buildings or to NASH Building Envelope Solutions for steel-framed buildings; and,
• situated in NZS 3604 and NASH Standard Part Two Wind Zones up to, and including, Very High.

Use over Rigid Wall Underlay

2. Hydra Classic Wall Underlay has been appraised for use as a flexible wall underlay over rigid wall underlays on buildings within the following scope:

• the scope limitations of NZBC Acceptable Solution E2/AS1 for timber-framed buildings; or,
• the scope limitations of NASH Building Envelope Solutions for steel-framed buildings; and,
• with absorbent and non-absorbent wall claddings installed over an 18 mm minimum drained cavity; and, 
• with masonry veneer in accordance with NZBC Acceptable Solution E2/AS1 for timber-framed buildings or NASH Building Envelope Solutions for steel-framed buildings; and, 
• situated in NZS 3604 and NASH Standard Part Two Wind Zones up to, and including, Extra High.

Specific Design

3. Hydra Classic 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 Hydra Classic Wall Underlay into their design, in accordance with the declared properties and the instructions of Marshall Innovations Ltd.