Thermakraft Covertek 407 Roof and Wall Underlay

Thermakraft Covertek 407 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 between two layers of non-woven spun-bonded polyolefin.

Roof underlay

Thermakraft Covertek 407 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.
• With masonry tile roof cladding.
• With metal tile and profiled metal roof cladding.
• Situated in NZS 3604 wind zones up to and including extra high.

Flexible wall underlay

Thermakraft Covertek 407 has also been appraised for use as a flexible wall underlay on buildings within the following scope:

• The scope limitations of NZBC Acceptable Solution E2/AS1 paragraph 1.1 for timber-framed buildings.
• The scope limitations of NASH Building Envelope Solutions paragraph 1.1 for steel-framed buildings.
• 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 NASH Building Envelope Solutions for steel-framed buildings.
• 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 407 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 Thermakraft Covertek 407 into their design in accordance with the declared properties and the instructions of Thermakraft Ltd.

• Thermakraft Product Data Sheet COVERTEK 407, issue 6, June 2020
• Thermakraft Installation Guide COVERTEK 407, issue 2, June 2020

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