Description

Thermakraft Covertek 405 Roof and Wall Underlay is a fire-retardant synthetic building underlay for use under roof and wall claddings.

The product consists of a micro-porous water-resistant film laminated to two layers of non-woven spun-bonded polyolefin. 

Scope

Roof Underlay

Thermakraft Covertek 405 Roof and Wall Underlay has been appraised for use as a self-supporting roof underlay on 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; and,
• with masonry tile roof cladding; and,
• with metal tile and profiled metal roof cladding; and,
• situated in NZS 3604 Wind Zones up to, and including 'Extra High'.

Thermakraft Covertek 405 Roof and Wall Underlay synthetic building underlay for use under roof and wall claddings. The product consists of a micro-porous water-resistant film laminated to two layers of non-woven spun-bonded polyolefin. 

Flexible Wall Underlay

Thermakraft Covertek 405  has also been appraised for use as a flexible wall underlay for buildings within the following scope:

• the scope limitations of NZBC Acceptable Solution E2/AS1, Paragraph 1.1 for timber-framed buildings; or,
• the scope limitations of NASH Building Envelope Solutions, Paragraph 1.1 for steel-framed buildings;
• with direct fixed absorbent and non-absorbent wall claddings; or,
• with absorbent and non-absorbent wall claddings installed over 18 mm minimum drained cavity; or,
• 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 2 Wind Zones up to, and including 'Very High'.
• situated in NZS 3604  and NASH Standard Part 2 Wind Zones up to, and including 'Extra High', when used over a rigid wall underlay in accordance with NZBC Acceptable Solution E2/AS1 or NASH Building Envelope Solutions Paragraph 9.1.7.2.

Specific Design

Thermakraft Covertek 405 has also been appraised for use for buildings subject to specific weathertightness design. Building designers are responsible for the building design and for the incorporation of Thermakraft Covertek 405 into their design in accordance with the declared properties and the instructions of Thermakraft Limited.