Pre-applied Building Underlay Protects CLT Panels from Moisture

Miles Construction have been quite busy of late erecting medium density houses and apartment developments all over the greater Auckland area. The developments, being built for Housing NZ and designed by RM Designs, are predominantly fabricated using CLT (Cross Laminated Timber) panels sourced from XLam. As the walls, mid floors and roofs are all constructed from the same pre-fabricated solid panels, the buildings are erected and closed in quickly compared to conventional lightweight timber framing, enabling work to commence on the interiors sooner in a nice dry environment, without waiting for frames to dry out.

Pro Clima SOLITEX EXTASANA ADHERO self-adhesive wall and roof underlay is typically pre-applied to the roof panels before they get to site, ensuring the most exposed part of the building is kept dry from the start, well before the roofing goes on. For a whole variety of reasons (including durability, warping and mould growth), it makes sense to not allow kiln-dried timber to get wet in the first place, instead of 'pre-wetting' it and then drying it out later.

Like all Pro Clima external underlays, EXTASANA ADHERO is vapour permeable to allow for any drying to occur, yet highly water-resistant with a non-porous membrane in the middle layer which achieves a water column of 10,000mm, or 100 times the amount required for roof underlays under E2/AS1. This is especially critical for this type of application where the underlay is in full contact with a substrate on a more horizontal plane, to ensure liquid water is not wicked through as would be the case with a porous building underlay. With ADHERO now achieving 180 days UV exposure, the need to get the roof on straight away is not as much of a concern either. BRANZ Appraised (Appraisal No 989), ADHERO can be used on buildings that fall within the scope of E2/AS1 and NZS3604, or for specific design scenarios outside of that scope.

The external walls of the houses are wrapped up in an initial layer of SOLITEX EXTASANA underlay as soon as possible to protect the CLT before Black Pearl external insulation is installed. A secondary layer of SOLITEX EXTASANA is then applied over the insulation to act as the weather-resistive barrier before cladding is installed, with TESCON EXTORA flashing tape used at laps and TESCON EXTOSEAL sill tape applied at the openings, to ensure the thermal envelope is kept dry, warm and airtight to perform efficiently in the long term.

Talking with Dave Salter from Miles Construction at the Avondale job, he said having done a few CLT builds now he prefers this method of building over traditional timber framing, because of the speed at which the jobs progress, and the fact the panels are always straight and true, which adds an element of precision to the build.

With the need to build faster to satisfy Auckland's housing demand, while at the same time improving the quality and performance of the housing stock, modern pre-fab building methods such as CLT panels coupled with innovative materials such as ADHERO and EXTASANA make an ideal mix to ensure both these boxes can be well and truly ticked.

Wall Underlay (SOLITEX EXTASANA)

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SOLITEX EXTASANA is a synthetic flexible wall underlay designed for New Zealand conditions, produced in Germany, and exceeds all of the testing standards of E2/AS1 Table 23.

Has been assessed for use as a flexible wall underlay on timber framed buildings within the following scope:

the scope limitations of NZBC Acceptable Solution E2/AS1, Paragraph 1.1; and,
with absorbent wall claddings directly fixed to framing; and,
with non-metallic, non-absorbent wall claddings directly fixed to frame; 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; and,
situated in NZS 3604:2011 Wind Zones up to, and including ‘Very High’.

Has been assessed for use as a flexible wall underlay on 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; 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; and,
situated in NZS 3604:2011 Wind Zones up to, and including ‘Very High’.

Has been assessed 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 (August 2011), Paragraph 1.1 with regards to building height and floor plan area; 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; and,
situated in NZS 3604:2011 Wind Zones up to and including ‘Extra High’

If used, designed, installed and maintained in accordance with the statements and conditions of the Installation Guide and the Codemark Certificate, will meet, or contribute to meeting the following provisions of the NZBC:

Clause B2 DURABILITY: Performance B2.3.1(a), not less than 50 years, B2.3.1(b), 15 years and B2.3.2. meets these requirements.
Clause E2 EXTERNAL MOISTURE: Performance E2.3.2. When used as part of the cladding system, will contribute to meeting this requirement.
Clause F2 HAZARDOUS BUILDING MATERIALS: Performance F2.3.1. Meets this requirement and will not present a health hazard to people.

BRANZ Appraised

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Sill Tape (TESCON EXTOSEAL)

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Butyl sill tape for use with wall underlays like SOLITEX EXTASANA and SOLITEX EXTASANA ADHERO and other weathertightness layers.

TESCON EXTOSEAL Sill Tape has been appraised as a flexible flashing system for use around window and door joinery openings for buildings within the following scope:

the scope limitations of NZBC Acceptable Solution E2/AS1 Paragraph 1:1; and,
with a risk score of 0-20 calculated in accordance with NZBC acceptable solution E2/AS1 table 2; and,
with wall cladding systems complying with NZBC acceptable solution E2/AS1 or a valid BRANZ Appraisal that specifies a flexible flashing system; and,
with flexible wall underlays compatible with flashing tape; and,
situated in NZ3604 Wind Zones up to, and including, Extra High.

TESCON EXTOSEAL Sill Tape has also been appraised as a flexible flashing system for use around window and door joinery openings for steel framed buildings within the following scope:

the scope limitations of NZBC Acceptable Solution E2/AS1 with regards to the building height and floor plan area; and,
constructed with a steel frame complying with NZBC; and,
with a risk score of 0-20 calculated in accordance with NZBC acceptable solution E2/AS1 table 2; and,
with wall cladding systems covered by a valid BRANZ Appraisal that specifies a flexible flashing system; and,
with flexible wall underlays compatible with flashing tape and steel frame; and,
situated in NZ3604 Wind Zones up to, and including, Extra High.

Used in:

Te Uru Taumatua — Living Building Challenge
Unitec, Weltec and Toi Ohomai student-built homes
Habitat for Humanity
Housing New Zealand

BRANZ Appraised

Self Adhesive Building Wrap (SOLITEX EXTASANA ADHERO)

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ADHERO is a peel-and-stick weathertightness layer for roof and wall application over a solid substrate.

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Appraised (BRANZ Appraisal 989) for use:

Over rigid wall underlays
Over rigid roof sarking
Over roofs and walls of SIP and CLT construction
Specific Design

SOLITEX EXTASANA ADHERO Self-Adhesive Underlay has been appraised for use as a wall underlay over fibre cement and plywood 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; 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 a specific design for steel framed buildings; and
situated in NZS 3604 Wind Zones up to and including Extra High

SOLITEX EXTASANA ADHERO Self-Adhesive Underlay has also been appraised for use as a roof underlay over plywood roof sarking 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; and
with roof claddings in accordance with NZBC Acceptable Solution E2/AS1, Paragraphs 8.1 – 8.4; and
situated in NZS 3604 Wind Zones up to and including Extra High

SOLITEX EXTASANA ADHERO Self-Adhesive Underlay has also been appraised for use as a wall and roof underlay when used on buildings within the following scope: p

the scope limitations of NZBC Acceptable Solution E2/AS1, Paragraph 1.1 with regards to building height and floor plan area; and
used on buildings constructed from Structural Insulated Panels (SIPs); or
used on buildings constructed of Cross Laminated Timber (CLT); and
with absorbent and non-absorbent wall claddings installed over an 18 mm minimum drained cavity; or,
with masonry veneer to a specific design for SIP or CLT buildings; and,
with roof claddings in accordance with NZBC Acceptable Solution E2/AS1, Paragraphs 8.1 - 8.4; and,
situated in NZS 3604 Wind Zones up to and including Extra High. (Note: CLT and SIP construction systems have not been assessed and are outside the scope of this Appraisal. See also Paragraph 7.12.)

SOLITEX EXTASANA ADHERO Self-Adhesive Underlay has also been appraised for use over rigid wall underlays or roof sarking on buildings subject to specific weathertightness design. Building designers are responsible for the building design and for the incorporation of SOLITEX EXTASANA ADHERO® Self-Adhesive Underlay into their design in accordance with the declared properties and the instructions of Pro Clima (NZ) Ltd.

SOLITEX EXTASANA ADHERO Self-Adhesive Underlay, if used, designed, installed and maintained in accordance with the statements and conditions of BRANZ Appraisal 989, will meet, or contribute to meeting the following provisions of the NZBC:

Clause B2 DURABILITY: Performance B2.3.1 (a), not less than 50 years, B2.3.1 (b), 15 years and B2.3.2. SOLITEX EXTASANA ADHERO Self-Adhesive Underlay meets these requirements. See Paragraphs 9.1 and 9.2. e
Clause E2 EXTERNAL MOISTURE: Performance E2.3.2. When used as part of the roof or wall cladding system, SOLITEX EXTASANA ADHERO Self-Adhesive Underlay will contribute to meeting this requirement. See Paragraphs 12.1 and 12.2.
Clause F2 HAZARDOUS BUILDING MATERIALS: Performance F2.3.1. SOLITEX EXTASANA ADHERO Self-Adhesive Underlay meets this requirement and will not present a health hazard to people.

BRANZ Appraised

TESCON EXTORA Multi-Purpose Weathertightness Sealing Tape

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TESCON EXTORA is a multi-purpose weathertightness sealing tape for windproof and weathertight sealing.

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TESCON EXTORA Sealing Tape has been appraised by BRANZ as a flashing tape for use around the head and jambs of window and door joinery openings for buildings within the following scope:

the scope limitations of NZBC Acceptable Solution E2/AS1, Paragraph 1.1; and,
with a risk score of 0-20, calculated in accordance with NZBC Acceptable Solution E2/AS1, Table 2; and,
with wall cladding systems complying with NZBC Acceptable Solution E2/AS1 or a valid BRANZ Appraisal that specifies a flexible flashing system; and,
with a compatible flexible wall underlay fixed directly to the framing or over-fixed over a rigid wall underlay; and,
situated in NZS 3604 Wind Zones up to, and including, Extra High.

TESCON EXTORA Sealing Tape has also been appraised as a joint-sealing tape for rigid wall underlays [fibre cement sheet and H3.2 treated plywood In accordance with NZBC Acceptable Solution E2/AS1] which are over-fixed with a flexible wall underlay in accordance with NZBC Acceptable Solution E2/AS1, Paragraph 9.1.7.2 on buildings within the following scope:

the scope limitations of NZBC Acceptable Solution E2/AS1, Paragraph 1.1; and,
with a risk score of 0-20, calculated in accordance with NZBC Acceptable Solution E2/AS1, Table 2; and,
with wall cladding systems complying with NZBC Acceptable Solution E2/AS1 or a valid BRANZ Appraisal; and,
situated In NZS 3604 Wind Zones up to, and including, Extra High.

In the opinion of BRANZ, TESCON EXTORA Sealing Tape, if designed, used, installed and maintained in accordance with the statements and conditions of BRANZ Appraisal 838 (2013), will meet or contribute to meeting the following provisions of the NZBC:

Clause B2 DURABILITY: Performance B2.3.1 [b], 15 years and B2.3.2. TESCON EXTORA Sealing Tape meets these requirements. See Paragraphs 8.1 and 8.2.
Clause E2 EXTERNAL MOISTURE: Performance E2.3.2.TESCON EXTORA Sealing Tape contributes to meeting this requirement. See Paragraphs 7.1- 7.5 and 11.1 - 11.5.
Clause F2 HAZARDOUS BUILDING MATERIALS: Performance F2.3.1. TESCON EXTORA Sealing Tape meets this requirement and will not present a health hazard to people.

BRANZ Appraised

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