Description

SOLITEX EXTASANA® Wall Underlay is a flexible synthetic absorbent wall underlay. The product consists of a monolithic water-resistant film laminated between two layers of non-woven spun-bonded polypropylene and is coloured blue on the top surface and grey on the bottom surface.

SOLITEX EXTASANA® Wall Underlay is a wall underlay for use under direct fixed and non-direct fixed wall cladding on timber framed buildings. SOLITEX EXTASANA® Wall Underlay is suitable for use as temporary weather protection for up to 180 days to allow interior works to continue inside the building without the exterior wall cladding fully in place.

Scope

1. SOLITEX EXTASANA® Wall Underlay use is certified as flexible wall underlay for buildings:

• a. within the scope limitations of NZBC Acceptable Solution E2/AS1, Paragraph 1.1 for timber-framed building, and
• b. with absorbent or non-absorbent wall claddings either direct fixed or installed over an 18 mm minimum drained cavity; or
• c. with masonry veneer in accordance with NZBC Acceptable Solution E2/AS1 for timber-framed buildings; and
• d. situated in
  • i. NZS 3604;2011 Wind Zones up to, and including, Very High; or
  • ii. NZS 3604:2011 2 Wind Zones up to, and including, Extra High when used
    • 1. over an 18 mm minimum drained cavity; and,
    • 2. over a rigid wall underlay in accordance with NZBC Acceptable Solution E2/AS1.

2. SOLITEX EXTASANA® Wall Underlay must be installed in accordance with:

• a. SOLITEX EXTASANA® Application Guide – Timber Frame; Dated 30/09/2025
• b. When used as temporary weather protection, SOLITEX EXTASANA® Early Close-In Application Guide for Horizontal Cladding Version 1.0 dated July 29 2025, SOLITEX EXTASANA® Early Close-In Application Guide for Vertical Cladding Version 1.0 dated July 29 2025 and SOLITEX EXTASANA® Early Close-In Application Guide for Brick Cladding Version 1.0 dated July 29 2025 (as appropriate)
• c. And the sets of drawings provided in the certificate.

3. Timber Framing: Studs must be provided at maximum 600 mm centres. Dwangs must be fitted flush between the studs at maximum 1200 mm centres.

4. SOLITEX EXTASANA® Wall Underlay must not be exposed to the weather or ultraviolet light for a total of more than 180 days before being covered by the wall cladding when used in either the normal or temporary weather protection options.

5. In cavity installations where the cavity battens are installed at greater than 450 mm centres, the wall underlay must be supported between the battens to prevent the underlay bulging into the cavity space when bulk insulation is installed in the wall frame cavity in accordance with the requirements of NZBC Acceptable Solution E2/AS1 (Paragraph 9.1.7.10.5) for timber frame. Wall underlay support options include polypropylene straps, 75mmm galvanised mesh or galvanised wire, and vertical cavity battens.

6. When used as a non-rigid backing material for stucco, SOLITEX EXTASANA® Wall Underlay must be supported with 75 mm galvanised mesh or plastic tape or wire at 150 mm centres run across the cavity battens to limit deflection to a maximum of 5 mm.

7. SOLITEX EXTASANA® Wall Underlay must be separated from fireplaces, heating appliances, HVAC, flues and chimneys in accordance with the requirements of Acceptable Solutions C/AS1, or C/AS2.

8. Contribution to compliance with Building Code clause H1.3.1(b) is conditional on:

• a. The element incorporating SOLITEX EXTASANA® Wall Underlay being part of the thermal envelope of the building, and
• b. horizontal and vertical laps being securely taped.