Why Tricore®?

Weather Secure – continuous roofing sheets with no end laps or joins which rely on sealant; the slotted roof rail and fastening system negates the use of long fasteners through the roof sheet that would flex due to thermal expansion.

Breathes – slotted roof rail design allows the required amount of air movement to control moisture resulting in lower moisture levels than other systems year round, removes the need to rely on a vapour barrier and reduces the risk of moisture accumulating sufficiently to cause corrosion of the roof sheet.

Insulates – consistent R-Value across the roof, reliable for the life of the roof; fastening system reduces energy loss from thermal bridging.

Aesthetic – your choice of roof profile including Dimondek 630 clip-fastened roof sheets in continuous lengths up to 90m*.

Straightforward – easy to install to Building Code requirements using the Metal Roofing Code of Practice; building is closed in quickly enabling sequencing of sub-trades to be optimised. Easy to maintain as the roof sheet can easily be replaced if damaged without disturbing the insulation.

For NZ – designed in New Zealand specifically for the rigors of New Zealand’s environment. New Zealand Building Code compliant to clause E2/AS1 and H1.

Warranty – 15 year system warranty.

The next generation in roofing is available today, specify Tricore® on your next commercial roofing project.

How it works

The Case for Ventilation vs Vapour Barrier

The Problem

In any insulated roof system the surface on the inside of the insulation is maintained close to the internal air temperature and the moisture in the air will therefore not condense on the inside surface. However, when the warm air migrates past the internal surface and through the insulation it will eventually reach a surface that is cool enough to cause the moisture in the air to condense. Accumulation of this condensation will reduce the effectiveness of the insulation and will cause long term issues with the durability of the insulated roof materials.

Vapour Barrier as a Solution

A vapour impermeable layer can be installed below the insulation to prevent the warm inside air from migrating anywhere. However, reliance on a vapour barrier solution is not recommended because no vapour barrier is 100 percent reliable since there will be laps in the material, fastener holes and also penetrations for services and lighting.

Ventilation as a Solution

Given that some warm internal air will migrate through the insulation it is sensible and essential to provide ventilation within the system that will allow any condensation that forms to dry out. Condensation moisture adjacent to the roof underside can result in corrosion of the roof sheet, and to prevent this it is essential that the moisture is removed. Modelling of climatic conditions shows that a relative humidity in excess of 90% can occur under the roof sheet for up to 8 months of the year unless adequate ventilation is available. It is known that prolonged exposure to Relative Humidity greater than 90% causes premature corrosion of the underside of steel roof sheets.

The Tricore® Solution

Tricore™ has a partial vapour barrier in the form of the profiled steel lining sheet. It is accepted that some warm internal air will migrate through laps in the lining sheets and through fastener holes.

The Tricore™ system includes a high quality roof underlay positioned on top of the insulation with sealed laps that permits transfer of water vapour but prevents condensation moisture from passing through to the insulation below.

The Tricore™ Roof Rail is positioned above the PIR insulation board and the roof underlay to create an air space immediately below the metal roof sheet.

Hence when condensation forms on the underside of the roof sheet (or in extreme cases possibly on the top surface of the underlay) it will be directly exposed to air movement in the air space and will dry out rather than accumulate. The air movement is facilitated by the design of the roof rail to allow sufficient air movement from eaves to ridge. The ventilation is driven by both air pressure difference between eaves and ridge and thermal buoyancy within the air space.

Thermal Insulation

Thermal Insulation

The Tricore™ insulated roof system uses high-quality Enertherm PIR rigid insulation in a range of thicknesses that can be selected to achieve the required thermal resistance.

Insulation Board

High-quality Enertherm PIR with tri-laminated aluminium foil facing to both sides, with minimal shrinkage over time

– Large panel sizes can be used minimising the risk of loss of R-value due to gaps at joins
– Density : 32 kg/m3
– Compression Strength : at 10% deformation ≥ 175 kPa (EN 13165)

Available as square edge
Complies with EN13165 for thermal performance

PIR Thickness (mm)
R* (m² °C/W)
R* (m² °C/W)
R* (m² °C/W)
R* (m² °C/W)
R* (m² °C/W)
R* (m² °C/W)
R* (m² °C/W)

* Based on PIR only without the additional R value from surface effects and additional Tricore components.

The Tricore® system is fastened to the structure in a way that minimises the effect of fasteners penetrating the insulation and ensures that the roof fasteners on the cold roof side of the assembly only penetrate as far as the ventilated roof rail and therefore do not form a thermal bridge to the warm internal side.

Similarly, the ventilated roof rail is located on the cold side of the insulation, which forms a continues separation from the warm support structure.

The quality of the Enertherm PIR rigid insulation is such that shrinkage of the panels does not occur to any extent that would result on gaps opening up between panels over time.

Tricore® details have been developed to ensure that the thermal envelope is continuous at gutter lines and ridge.

Condensation control

Condensation Control

The potential for condensation to form within the Tricore® system is minimised by the use of a combination of vapour barriers and air space ventilation.

The NPM 900 lining sheet forms a partial vapour barrier beneath the Enertherm PIR insulation. Consideration of a range of internal and external climate conditions has been carried out using WUFI computer modelling to ISO 13788, including NIWA data over a 1 year period for both Auckland and Queenstown environments.

Results indicate that the Dew Point will be on the roof sheet underside or on the roof underlay on the top surface of the PIR insulation, and therefore the Tricore® system has been designed to provide a ventilated air space between the roof underside and the roof underlay. The ventilation that can then occur in the air space acts to prevent abuild up of moisture and relative humidity against the roof underside. This prevention is critical to the durability of the roof material.

The WUFI analysis showed that a system without the ventilated air space immediately below the roof sheet could expect to have a relative humidity in excess of 90% for up to 8 months of the year, whereas the Tricore® ventilated system could expect a relative humidity below 90% and thereby minimise the risk of roof sheet underside corrosion .

Acoustic Performance

Acoustic Performance

Sound transmission through the roof and into an enclosed building space is typically either airborne sound (from sources such as road traffic or aircraft) or structure borne sound (from rainfall impact on the roof surface). The Tricore® Insulated Roof System can be designed to reduce sound levels within the building space for either or both of these sound transmission cases.

The Tricore™ Acoustic Performance Guideline table provides a sound transmission design guide for expected performance based on acoustic laboratory testing and expert opinion from Marshall Day Acoustics. The information is given as a guide only for a reasonable expectation of performance since the as-built performance will depend on construction details and quality of finish that are both outside the scope of the acoustic analysis.

Sound Transmission Class (STC) is a measure of the reduction of airborne sound achieved by the Tricore® system in combination with either integral layers of board and/or different types of suspended ceiling. High STC values represent better performance.

Rain Noise (NC) is a measure of the sound level expected in the building space resulting from a range of rainfall rates. It is given for two types of building space. Note that the rainfall rate is the average rainfall over a one hour period and not peak rainfall. Low NC values represent better performance.

It is clear from the design guidelines that for buildings where sound level reduction is critical to occupant comfort the most effective design approach is to use a suspended ceiling rather than include extra mass by way of layers of board within the Tricore® Insulated Roof System.


1. The Tricore® insulated roof system includes 0.55 mm steel liner, PIR insulation board in a range of thicknesses from 50mm to 120mm, roof underlay, 27.5mm air space, 0.55mm steel roof sheet.

2. Reference space descriptions for guideline NC performance:

Building Space

Floor / Roof Area (m2)

Floor to Ceiling Height (m)

Reverberation Time (seconds)





Open-plan Office



0.7 – 0.8

Gymnasium / large reverberant space




3. Additional mass layer integrated with Tricore® can be placed either over or under the PIR insulation board with 5mm maximum gap between boards. Guideline performance based on 10mm Gib Weatherline at nominal 8.6 kg/m2 or 13mm GIB Weatherline at nominal 11.2 kg/m2.

4. Suspended ceiling performance is based on a minimum 200 mm space between the ceiling and the Tricore steel liner, no acoustic blanket in the cavity, 13mm GIB plasterboard (nominal 8.7 kg/m2) fixed to a lightweight steel grid, mineral fibre ceiling tiles (nominal 3.6 kg/m2), or fibreglass ceiling tiles (nominal 1.5 kg/m2) in a lay-in grid.

5. Rainfall rate is the average rainfall over one hour based on an appropriate return period for the location and building use.

6. STC and NC values are based on test and calculation by Marshall Day Acoustics Ltd (Report Rp002 r03 20170140, 3 July 2019) and are given as general performance guidelines only. It is reasonable to expect performance to be achieved within +/- 2 dB of the STC guideline and +/- 3 dB of the NC guideline. Final design and acoustic performance is the responsibility of the design engineer for each specific building project and must account for specific requirements and as-installed site conditions.


Prefinished Lining Sheet

NPM 900 profile in Zincalume or ColorCote® finish if left exposed as visible lining, available in 0.40, 0.55 or 0.75 mm steel thickness to suit purlin spacing and construction loads.

Pan-fixed to purlins to achieve rapid enclosure of the building.

Maximum spans to support 1kN foot traffic load and 2.0kPa† ultimate limit state (ULS) wind load.
NPM 900
End Span (mm)
Internal Span (mm)

Based on fastening every second pan of all sheets on all purlin lines.

Slotted Roof Rail

Enables free flow of ventilation air and drainage of any moisture that may be present.

Ventilated air space ensures moisture accumulation is removed from the underside of the roof sheet. Given this, Relative Humidity at the roof sheet underside is not expected to exceed 90%. By comparison, an insulated roof build-up that does not have a sufficiently ventilated space below the roof sheet could be expected to have a Relative Humidity at the roof sheet underside exceeding 90% for up to 8 months of the year, creating a significant risk of roof sheet corrosion.

Ensures that any leakage at the roof fastener is managed by the roof underlay, preventing fastener leakage entering the PIR.

Enables the roof fasteners to be separated from the fasteners that penetrate the warm side of the system.

Galvanised steel to provide sufficient screw holding fastened through the PIR board and into the structural purlin at 300mm centres.

Roof Sheet and Underlay

Choice of long run profile, with no end laps or reliance on sealant to achieve weather security, including clip fastened Dimondek 630 to remove fastener penetration of the roof sheet.

Proven load/span data for each roofing profile based on product testing and history of use.

Underlay is supported by the PIR boards and absorbs any moisture present below the roof sheet, releasing it to drying air in the ventilated space below the roof sheet.


Relevant Product CAD Details

Below you will find all of the relevant product CAD technical details in .dwg, .pdf & .rvt format.

If you have any questions regarding the details below please contact one of our technical team on 0800 ROOFSPEC.

Download all .dwg as zipUpdated November 2019
Product Technical Statement

Product Technical Statement

To help you get through the building consent process as quickly as possible, we have developed the Product Technical Statement (PTS) downloads to make it quick and easy for both Architects and Home Owners to access the documentation required.

The PTS downloads hold all of the information that the council requires for a building consent where Dimond product is specified.

Download Product Technical StatementLast updated November 2021

Product Brochure

Need a brochure for this product? Here you can download one with the basic information and details you need during the decision process.

Download Product BrochureLast updated May 2021