New SASH Developments Offer Social Housing with a Difference

The brief given to Fat Parrot Architecture by the Salvation Army for their new Auckland SASH units was simple; "Help us create great social housing communities which really enhance people’s quality of life." There was a real desire to look at the problem with a fresh set of eyes and be innovative. They were keen to create ‘something better’ and not just add to New Zealand’s large stock of minimum spec housing, where residents are often forced to decide between ‘heating or eating’ through the winter months.

After researching the costs and benefits of various construction methods, the team at Fat Parrot settled on the Formance SIPS (Structural Insulated Panel System) as their construction system for the SASH developments, which are currently under construction around the Auckland region. Experienced SIPS builders Meridian Construction were engaged early on as the main contractor, which helped keep control of costs on a tight project budget.

For the design and build teams, thermal performance and speed of construction were the deciding factors in going with SIPS over standard timber framing. SIPS generally have higher R values compared to a timber-framed wall with fibrous insulation of similar thickness, due to the type of insulation used and the lack of thermal bridges within the panel. As SIPS buildings are constructed using solid panels on the roof and walls, the buildings are often closed in more quickly which allows interior work to take place earlier.

On the SASH units pro clima SOLITEX MENTO 1000 connect was applied to all roof/soffit areas once the panels were erected. SOLITEX MENTO 1000 connect is a WRB (Weather Resistive Barrier) membrane which is extremely water-resistant while being highly vapour permeable, so construction moisture (if any) can dry off once installed. The laps of SOLITEX MENTO 1000 connect are sealed with the built-in ‘connect’ adhesive strips on either edge of the membrane and are staple fixed under the lap above the connect strip only, to avoid wind-driven moisture wicking up the laps.

pro clima TESCON NAIDECK butyl strip was used under the ventilated cavity battens on the roof to ensure all screw penetrations through SOLITEX MENTO 1000 connect were made watertight. pro clima SOLITEX EXTASANA WRB was used on all wall panels and connects to SOLITEX MENTO 1000 connect on the roof. pro clima TESCON EXTOSEAL one piece sill tape was applied to window and door openings while pro clima TESCON EXTORA was used for sealing laps in the wall underlay and above the joinery head flashings. As with other building control layers (air, vapour, thermal) this combination of products ensures continuity of the exterior water control layer, which is essential for the durability and performance of the SIPS long term.

Panelised constructions such as SIPS are naturally quite airtight, especially once the interior panel joints are taped as per manufacturer’s recommendations. Blower Door testing conducted at the SASH Westgate units showed an average Air Permeability (or air leakage) through the building envelope of less than 3m³/hr/m² of envelope area @50Pa pressure difference, which is roughly half the amount of air leakage you might expect to see in a typical new timber-framed house.

An airtight thermal envelope allows more efficient use of the heat generated within the unit and ensures internal moisture does not infiltrate and condense within the construction causing mould growth. And if using a balanced ventilation system, the more airtight the better, to ensure more control of the interior climate. Lunos discreet through wall MHRV systems are installed into every unit to ensure a constant supply of fresh, drier air with heat being recovered from the extracted moisture-laden air. So, there should be no need to open windows on cold winter mornings to ventilate the interior.

Architect Llyween Watts said a key design feature of the SASH developments is that all units have a North facing living room and a private North facing outdoor living area, to ensure all residents can enjoy the benefits of natural sunlight and warmth inside and outside. Each unit has a small panel heater fitted as required by building regulations, but Llyween doubts the residents will need to use them much as even during construction the thermal comfort was very evident, a fact all parties involved are thrilled with and great news for those who will very soon be making these units their homes.

Roof Underlay (SOLITEX MENTO 1000)

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SOLITEX MENTO 1000 roof underlay is a three-layer roof underlay designed to be used with most typical roof cladding systems. While providing temporary weather protection it can remain exposed for up to 30 days.

SOLITEX MENTO 1000 has been appraised for use as a self-supporting roof underlay on buildings within the following scope:

the scope of 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 profiles metal roof cladding; and,
suited to NZS 3604 Wind Zones up to, and including Extra High.

In the opinion of BRANZ, SOLITEX MENTO 1000, if used, designed, installed and maintained in accordance with the statements and conditions of Appraisal No.876 (2014), 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 MENTO 1000 meets these requirements.
Clause E2 EXTERNAL MOISTURE: Performance E2.3.2. When used as part of the roof cladding system, SOLITEX MENTO 1000 will contribute to meeting this requirement.
Clause F2 HAZARDOUS BUILDING MATERIALS: Performance F2.3.1. SOLITEX MENTO 1000 meets this requirement and will not present a health hazard to people.

SOLITEX MENTO 1000 has been Appraised as an Alternative Solution in terms of the New Zealand Building Code Compliance.

Durability

External Moisture

Hazardous Building Materials

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’

Low Wind Zone

Very High WInd Zone

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.

Durability

External Moisture

Hazardous Building Materials

BRANZ Appraised

CodeMark

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.

LBC Red List Free

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.

Durability

External Moisture

Hazardous Building Materials

BRANZ Appraised

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

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