Increasing Thermal Performance Through Warm Roof Design

A true warm roof is defined as a system in which when insulation is placed outside of the structure, it can provide high thermal performance for the building, minimising the risk of heat loss and eliminating thermal bridging. The warm roof must have sufficient insulation quality, specific to the building’s climatic location and intended building use.

Overall, the addition of a warm roof system can drastically increase the energy efficiency of a building. This is done by providing a continuous insulation layer to ensure there are no thermal breaks in the structural framework. This equates to both heat and energy savings due to consistent internal temperature.

Warm roof construction vs. thermally broken construction

A typical E2 type timber structure roof requires timber supports at 400mm centres. If using 90mm wide timber, this equates to approximately 27% of the roof’s total surface area. In a traditional lofted roof situation where insulation is put between the rafters, a considerable amount of time, cost and energy are used. This time-consuming thermally broken construction method often results in an R-value which is considerably lower than that of a warm roof.

In addition, condensation can be an issue. In a typical construction, the warm moisture-laden air rises and would condensate on cold elements within the roofing structure. In the past, the removal of this moisture-laden air has been accommodated by installing vents on the roof, which creates unnecessary penetration. This can allow cold damp air to enter the building space under the right conditions. If warm roof construction is used instead, and an efficient insulation layer is installed outside the structure, the external dew point is shifted, effectively eliminating condensation within the building.

Nuralite's Nuratherm Warm Roof System goes one step further. The use of a metal tray substrate underneath PIR insulation boards in lieu of traditional plywood substrates offers many benefits as the greater spanning capabilities of the metal tray profile reduce installation time and create a weathertight building faster.

Warm roofs are not a new system and although relatively new to New Zealand, warm roof construction is compulsory in most other parts of the world. Warm roofs are increasingly becoming more common in New Zealand as leading designers see the system as a total solution to combat condensation and heat loss. Cost savings can also be achieved as there are fewer costs associated with long term heating, cooling and ventilation of the building.

Enertherm PIR Insulation Boards

Nuralite

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Enertherm PIR is a 100% CFC, HCFC or HFC-free insulation board with a rigid polyisocyanurate foam core, clad on both sides with a multi-layer gas-tight aluminium complex.

Enertherm boards can be installed over plywood, concrete or metal substrates, on new or existing buildings and on flat roofs with a minimum 1:30 slope.

IKO Enertherm ALU Insulation is installed as part of the Nuratherm System.

In the opinion of BRANZ, the Nuraply Nuratherm System if designed, and used, installed and maintained in accordance with with the statements and conditions of Appraisal No.732 (2012), will meet the following provisions of the NZBC:

Clause B2 Durability: Performance B2.3.1(b), 15 years. Nuraply Nuratherm System meet these requirements.
Clause E2 External Moisture: Performance E2.3.1 and 2.3.2. Nuraply Nuratherm System meet these requirements.
Clause F2 Hazardous Building Materials: Performance F2.3.1. Nuraply Nuratherm System meet these requirements and will not present a hazard to people.
Clause H1 Energy Efficiency: Performance H1.3.1(a). The Nuraply Nuratherm System will contribute to meeting this requirement.

Nuraply Nuratherm System have been appraised as an Alternative Solution in terms of New Zealand Building Code compliance.

BRANZ Appraised

Nuratherm Warm Roof System

Nuralite

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The Nuratherm system puts the insulation where it should be, above the substrate, to completely enclose the roof area with a highly efficient insulation blanket.

The Nuraply Nuratherm System has been appraised by BRANZ 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, timber 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); and,
with no integral roof gardens; and,
situated in NZ3 3604 Wind Zones, up to, and including 'Extra High'.

The Nuraply Nuratherm 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 Nuraply Nuratherm System into their design in accordance with the declared properties and instructions of Nuralite Waterproofing Ltd.

In the opinion of BRANZ , the Nuraply Nuratherm System, if designed, and used, installed and maintained in accordance with with the statements and conditions of Appraisal No.732 (2012), will meet the following provisions of the NZBC:

Clause B2 Durability: Performance B2.3.1(b), 15 years. Nuraply Nuratherm System meet this requirement
Clause E2 External Moisture: Performance E2.3.1 and 2.3.2. Nuraply Nuratherm System meet these requirements
Clause F2 Hazardous Building Materials: Performance F2.3.1. Nuraply Nuratherm System meet this requirement and will not present a hazard to people
Clause H1 Energy Efficiency: Performance H1.3.1(a). The Nuraply Nuratherm System will contribute to meeting this requirement

Nuraply Nuratherm System is appraised as an Alternative Solution in terms of New Zealand Building Code compliance.

BRANZ Appraised

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