Viking WarmSpan Improves Weathertightness and Thermal Efficiency

The Dunedin Public Art Gallery needed a new roof. The existing one was a mixture of profiled metal and membrane installed on both ply and concrete substrates. The building had serious condensation issues and the old butyl membrane seams were letting in water, thus deeming the roof-mounted plant susceptible to collapsing through the decaying timber substrate.

The Dunedin City Council set a strict brief for the Art Gallery’s new roof — it needed to improve both weather tightness and thermal efficiency. It was also paramount that the new roofing solution be installed without disrupting or removing the items housed in the building and that the building remained operational.

Viking WarmSpan was specified for this reason, but also because the lightweight nature of Viking WarmSpan would significantly reduce the stress on the building without compromising its structural integrity.

Viking WarmSpan is a BRANZ appraised, warm-roof-on-steel roofing system designed for low-sloped roofs. It has been engineered in New Zealand and is one of the country’s simplest and most energy-efficient warm roof systems. The full proprietary system is made up of three components:

A wide-spanning steel tray roof deck that also forms the vapour barrier
KingSpan Polyisocyanurate rigid insulation panels adhered on top, waterproofed with
One of Viking’s Membrane Systems

The first stage was to remove, recycle, and replace the 550m² of tired rubber membrane as well as the steel roofs.

Viking WarmSpan was installed, incorporating its trapezoidal steel substrate, integrated vapour barrier, and two layers of 50mm polyiso insulation to achieve a continuous R-rating of R4. Heat-weldable Viking Enviroclad TPO membrane was installed in 3m wide rolls, ensuring no end-laps as each roll extended the full width of the roof.

Unlike plywood or concrete substrates, the steel substrate made the roof 100% watertight from the early stages and a permanent roof safety system was also installed to the perimeter.

The workmanship of the Viking Approved Applicator was put to the test when 15 students climbed from a neighbouring building, jumped the razor-wire perimeter and had a party on the newly installed roof. The roof survived comfortably — the robust nature of Viking’s materials, along with the quality of workmanship, proving to be a winning durable combination.

WarmSpan Tray System

Viking Roofspec

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Viking WarmSpan is a warm roof that includes a proprietary steel tray substrate, supplied by Viking, to make up a complete roof system.

The Viking WarmSpan System has been appraised for use as an insulating roof on buildings within the following scope:

the scope limitations of NZBC Acceptable Solution E2/AS1, Paragraph 1.1 with regards to building height and maximum floor plan areas; and,
on limited access flat roofs with steel structural decks subject to specific structural design; and,
with roofs constructed to drain water to gutters and drainage outlets complying with the NZBC; and,
with roofs constructed to suitable falls (refer paragraph 15.3 and 15.4 of the Viking Warm Roof BRANZ Appraisal); and,
with no integral roof gardens; and,
situated in NZS 3604 Building Wind Zones, up to, and including Extra High.

The Viking WarmSpan System has also been appraised for durability and thermal performance as an insulated roofing system on buildings that are the subject of specific design with no building height restriction. Building designers are responsible for the building design and for the incorporation of the Viking WarmSpan System into their design in accordance with the declared properties and instructions of Viking Roofspec.

Clause B1 STRUCTURE: Performance B1.3.1. The Viking WarmSpan System meets this requirement.
Clause B2 DURABILITY: Performance B2.3.1 (b), 15 years. The Viking WarmSpan System meets this requirement. See paragraph 10.1 of the Viking Warm Roof BRANZ Appraisal.
Clause E2 EXTERNAL MOISTURE: Performance E2.3.1 and E2.3.2. The Viking WarmSpan System meets these requirements. See paragraphs 15.1 - 15.9 of the Viking Warm Roof BRANZ Appraisal.
Clause F2 HAZARDOUS BUILDING MATERIALS: Performance F2.3.1. The Viking WarmSpan System meets this requirement and will not present a health hazard to people.
Clause H1 ENERGY EFFICIENCY: Performance H1.3.1 (a). The Viking WarmSpan System will contribute to meeting this requirement. See paragraph 14.1 of the Viking Warm Roof BRANZ Appraisal.
Clause C/VM2 FIRE PERFORMANCE (of wall and ceiling linings) - ISO9705, Group 1S = highest possible rating.

BRANZ Appraised

Enviroclad (TPO) Waterproofing Membrane

Viking Roofspec

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Viking Enviroclad offers absolute watertight integrity for low-slope roofs.

NZ-Owned Business

Viking Enviroclad Roofing and Deck Membrane System has been assessed as a roof and deck waterproofing membrane on buildings within the following scope:

the scope limitations of NZS 3604:2011 and NZBC Acceptable Solution E2/AS1, paragraph 1.1; or,
the scope limitations of NZBC Acceptable Solution E2/AS1, paragraph 1.1 with regards to building height and floor plan area when subject to specific structural design; and,
situated in NZS 3604:2011 Wind Zones, up to, and including Extra High; and,
with substrates of plywood or suspended concrete slab

Viking Enviroclad Roofing and Deck Membrane System has also been assessed for use as a roof and deck waterproofing membrane on specifically designed or existing buildings within the following scope:

subject to specific structural and weathertightness design situated in wind pressures up to a maximum design differential ultimate limit state (ULS) of 2.7 kPa; and,
with substrates of plywood or suspended concrete slab
with the weathertightness design of junctions for each specific structure being the responsibility of the building designer

Clause B1 STRUCTURE: Performance B1.3.1, B1.3.2 and B1.3.4 (b) (c) (d) (e) for the relevant physical conditions of B1.3.3 (a), (c), (e), (h), (m) and (p) Viking Enviroclad Roofing and Deck Membrane System meets this requirement.
Clause B2 DURABILITY: Performance B2.3.1 (b) and B2.3.2 (a), 15 years. Viking Enviroclad Roofing and Deck Membrane System meets this requirement.
Clause E2 EXTERNAL MOISTURE: Performance E2.3.1, E2.3.2 and E2.3.7 (b) and (c). Viking Enviroclad Roofing and Deck Membrane System meets these requirements.
Clause F2 HAZARDOUS BUILDING MATERIALS: Performance F2.3.1. Viking Enviroclad Roofing and Deck Membrane System meets this requirement and will not present a health hazard to people.

BRANZ Appraised

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