Rainwater Harvesting Done Right on Waiheke Island

A luxurious five-level home on Waiheke Island was constructed into a steep bank, requiring a specialised waterproofing solution for a 45m², 1.6 m-high water tank located beneath the garage floor. This water tank was critical for rainwater collection a vital resource for the Waiheke community, which depends on harvested rainwater for daily needs.

Challenge

Given the confined space of the tank, safety was paramount during installation. Allco's applicator ensured proper airflow, monitored toxic gases and oxygen levels using specialised equipment, and maintained mechanical ventilation to guarantee safe working conditions.

Solution

Allco’s JM TPO membrane was selected as the ideal waterproofing solution. It is specifically designed for water collection applications and meets the rigorous standards of AS/NZS 4020:2018, proving its suitability for potable water harvesting.

The membrane successfully passed critical tests for:

Taste and appearance
Microorganism growth
Toxic substances
Mutagenic activity
Metals

Outcome

The installation of Allco’s JM TPO membrane provided a durable, sustainable, and certified solution for rainwater harvesting, aligning with the growing demand for eco-friendly and cost-effective water collection systems.

For more information or to discuss your project, contact the Allco team today.

JM TPO Membrane

Allco Waterproofing Solutions

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Johns Manville is widely recognised as one of the world's foremost suppliers of single ply roofing membrane, Allco has selected the JM TPO for their Cold Roof solution due to its superior UV and Ozone resistance and its impressive environmental credentials.

Suitable for use in the following locations:

In wind zones:
- Up to and including Extra High as defined by NZS 3604:2011.
- Where specifically designed up to (ULS) 3.0kPa.
In all climate zones as defined by NZS-3604:2011.

Up to and including Extra High as defined by NZS 3604:2011.
Where specifically designed up to (ULS) 3.0kPa.

Suitable for the following buildings:

On new buildings that have been designed and constructed to comply with the NZ Building Code (NZBC), particularly B1 (structure) as it relates to the construction of the substrate and substrate framing and E2.3.1 (surface water run off) as it relates to the shedding of water.
On existing buildings where the designer and applicator have ascertained that the existing building is suitable for the intended building work.

On the following substrates that incorporate a slope between 1.150 (1:50) 2.30 - 1.150 (1:25), or gutters at with a 0.5° (1:100) fall:

H3.2, CCA treated structural plywood
In situ reinforced concrete
Pre-fabricated concrete panels

In the opinion of BRANZ, JM TPO Membrane, if designed, used, installed and maintained in accordance with the statements and conditions of the Appraisal, will meet the following provisions of the NZBC:

Clause B2 DURABILITY: Performance B2.3.1 (b) 15 years. JM TPO Membrane meet this requirement. See Paragraph 10.1.
Clause E2 EXTERNAL MOISTURE: Performance E2.3.1, E2.3.2 and E2.3.6. Roofs incorporating JM TPO Membrane meet these requirements. See Appraisal paragraphs 13.1 – 13.4
Clause F2 HAZARDOUS BUILDING MATERIALS: Performance F2.3.1. JM TPO Membrane meet this requirement and will not present a health hazard to people

See BRANZ Appraisal for full information.

BRANZ Appraised

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