A Roof Refurbishment with Minimal Disruption? Overlaying a 2100m² Leaky Apartment Roof with the Viking Warm Roof System

On the corner of Khyber Pass and Symonds Street in Auckland City are the Citta Apartments; home to 105 residences, 90 carparks and a commercial premises on the ground floor — all well overdue for refurbishment. The dozens of penetrations through the low-pitch metal roof were leaking and the old butyl rubber lining the internal gutters was ready for replacement. Being predominantly residential apartments, it was also time to improve the energy efficiency of the building.

It was important that the refurbishment cause the least amount of disruption to the occupants. Rather than uplift and remove the roof while facing the expense and inconvenience of relocating the inhabitants while also filling the local landfill up with construction waste, the decision was made to overlay the existing metal roof by installing a Viking WarmRoof, with Viking Enviroclad membrane to ensure watertightness.

With the building completely shrink wrapped, the installation of a new waterproofing system to the 2100m² roof area was completed in stages:

The building contractor lifted the existing metal roofing to address any decay and install fire-proofing. The metal roof was then laid back down and converted to a warm roof vapour barrier by sealing and taping all air gaps in the body of the roof and around the perimeter. The internal gutters were also rebuilt to create new falls with the addition of new TPO-weldable scuppers.
75mm thick Polyiso insulation board was adhered to the metal roof substrate using a specialised polyurethane foam adhesive, followed by the installation of 1.52mm thick Enviroclad membrane with its proprietary accessories to complete the system and achieve full watertight integrity.
Discussions with the main contractor led to the Approved Applicator steering them away from their initial plan to include a full traditional walkway system (which would add 60-80 penetrations of the membrane; all vulnerable junctions needing to be waterproofed). Instead, they convinced them to install proprietary heat-welded Enviroclad walkway which rolls directly onto the membrane resulting in zero penetrations, and a fit-for-purpose, robust, grippy solution.

The Approved Applicator had to work with the existing parapets which varied in shape and width, making it difficult to apply the membrane in one piece. Instead, the team applied smaller, workable sections of Enviroclad with strategically positioned lap joins to negate membrane creasing.

Having taken years to get the go-ahead for the refurbishment of this prestigious project, all stakeholders had to approach this project with caution; a lot of planning, flexibility, and coordination with the main contractor. The end result is nothing less than first-class and is exemplary of the skill and workmanship of the licensed installers. The consultants, main contractor, architects and Body Corporate are very impressed with the system and have since proposed the same process on similar projects requiring the same type of solution.

WarmRoof System

Viking Roofspec

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The most commonly accepted definition of a warm roof (for low slope roofs) is 'a roof where the insulation is installed on top of the roof structure' i.e.

NZ-Owned Business

The Viking WarmRoof 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 concrete, plywood or 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 WarmRoof 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 WarmRoof System into their design in accordance with the declared properties and instructions of Viking Roofspec.

Clause B1 STRUCTURE: Performance B1.3.1. The Viking WarmRoof System meets this requirement.
Clause B2 DURABILITY: Performance B2.3.1 (b), 15 years. The Viking WarmRoof System meets this requirement. See paragraph 10.1 of the Viking WarmRoof BRANZ Appraisal.
Clause E2 EXTERNAL MOISTURE: Performance E2.3.1 and E2.3.2. The Viking WarmRoof 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 WarmRoof System meets this requirement and will not present a health hazard to people.
Clause H1 ENERGY EFFICIENCY: Performance H1.3.1 (a). The Viking WarmRoof System will contribute to meeting this requirement. See paragraph 14.1 of the Viking WarmRoof 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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