Ph 1300 722 832
Thermal Insulation: Thermax™

Quick link:    Thermax Sheathing

Dow Thermax Light Duty Soffit Board™exposed Car Park applications

Dow Thermax Light Duty™ thermal insulation sheathing distributed by Greenspec Solutions is a non-structural, rigid board consisting of a glass fibre reinforced Polyisocyanurate (PIR) thermoset foam core laminated between reflective aluminium foil facers on both sides.

Dow Thermax Light Duty™ has a glass fibre reinforced PIR thermoset foam core, along with chemical modifications, contribute to improved fire performance and dimensional stability. The Thermax Light Duty™ PIR foam core will not melt, flow or drip when exposed to fire, instead it will form a strong char that prevents flame spread and further degradation to the core, unlike EPS (Expanded Polystyrene) which will spread the flame due to oxygen being held between the cells within the panel. EPS cells are a thermoplastic material, which tend to melt and shrink when exposed to an intense heat.

Dow Thermax Light Duty™ PIR thermal insulation has bonded aluminium foil facers which serve as effective moisture vapour retarders. Thermax Light Duty™ PIR thermal insulation can be installed exposed to the interior without a thermal barrier which offers a high insulating value.


  • Thermax Light Duty is a thermal insulation which is suitable for:
    • Roof Insulation - Flat Concrete Roof
    • Floor Insulation - Concrete Floor Soffit (such as exposed car park applications)
  • Thermax Light Duty can also be fitted in standard interior wall and/or ceiling systems.


  • Durable white acrylic-coated aluminium on one side and an embossed aluminium on the other, both suitable for light-impact areas.
  • It can be pressured-washed up to 6,894 kPa with a 15-degree or greater spray tip

NCC/BCA Standards

Dow Thermax Light Duty Soffit Board™ has been subjected to the Full Burn Room Test – AS/ISO 9705, successfully passing this test and receiving a Group 1 Classification for soffit/ceiling applications.

In June 2012 , Standards Australia published Amendment 1 to the fire standard AS/NZS 3837, a fire test required by the National Construction Code (NCC) for materials used in building linings, such as insulation used in exposed concrete soffits. The amendment now prohibits the use of thermoplastic materials that melt and shrink away from a flame (eg. Expanded Polystyrene (EPS) and Extruded Polystyrene (XPS) materials).

Where an insulation material is to be left exposed as a finish, surface, lining or attachment (For Example. a basement car park), then the material must comply with the following D-T-S Provisions as outlined in the NCC: NCC Volume 1­­­­_Section C – Fire Resistance; (Specification C1.10 – Fire Hazard Properties_4. Wall and Ceiling Linings). For further information please contact our Technical Advisory Service or seek the advice of your Building Surveyor.

Compressive Strength: 172 kPa
Density: 32 kg/m³
Width: 1220 mm
Length: 2235 mm
Water Absorption: 0.5 %
Thermal K Value: 0.022 W/mK
Fire Rating: AS/NZS 1530 Part 3
AS/NZS 3837 Group1
ISO 9705 Group 1

Green Star Compliant
Zero ODP


Dow Thermax FM Approved - Soffit Board (PDF)

Pricing and
Where to Buy