EXPOL ThermaSlab S, M and H Grades for Roof Insulation

EXPOL ThermaSlab is a rigid foam board that keeps buildings warm, healthy and dry through optimum thermal protection.

Environmentally sound and long-lasting, EXPOL ThermaSlab is easy to handle and solves the challenge of effectively insulating narrow roof spaces, such as skillion roofs.

EXPOL ThermaSlab comes in full sheets and is easily cut to fit purlin or rafter spaces.


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Skillion Roof Insulation

EXPOL ThermaSlab is a thin, lightweight board that provides solid insulation in narrow roof spaces. The rigid foam composition of EXPOL ThermaSlab ensures thermal performance will not decrease over time. Available in full sheets, EXPOL ThermaSlab is easily cut to fit purlin or rafter spacings.

Other Applications

EXPOL ThermaSlab is also suitable for use as concrete slab insulation, retaining wall insulation, cladding insulation and wall insulation.


Up to 20% of a building's heat is lost through its roof. A building protected with EXPOL ThermaSlab insulation ensures a comfortable, healthy indoor environment for occupants.

EXPOL ThermaSlab is a lightweight polystyrene board that does not compromise on insulation performance. The cellular structure ensures that moisture does not affect the thermal performance of the board.

An exceptionally durable product, EXPOL ThermaSlab does not require maintenance or replacement. Thermal performance and resistance to moisture and water will last for the life of the building. EXPOL's expanded polystyrene insulation does not decay or rot and has no nutritional value to termites or rodents.

EXPOL ThermaSlab is easy to cut and comes in a range of sizes making the installation process fast and efficient.

EXPOL supplies EXPOL Platinum Board for a premium roof insulation solution.




EXPOL Wireguard is a waxed paper strip that separates exposed electrical cables from EXPOL ThermaSlab insulation. An important part of the system, EXPOL Wireguard prevents the degrading effect that EPS can sometimes have on electrical cables over a prolonged period.



EXPOL supplies a water-based glue to adhere polystyrene to most surfaces. EXPOL ThermaSlab insulation panels are glued in place using adhesive or can be used in combination with other fixing methods.



EXPOL ThermaSlab comes in full sheets in a range of widths. Sheets can be cut to specific sizes.




EXPOL makes insulating easy. To ensure you get the best result, follow these simple steps.

Installing EXPOL ThermaSlab

Ensure insulation is cut accurately to create a neat fit between the rafters or purlins.

It is important to ensure maximum insulation by using the correct thickness, as determined by the thickness of the rafters or purlins.

Check with the architect or specifier for required measurement for an air gap above the insulation.

Ensure there is no contact between the polystyrene and electrical wiring.

Technical information




What's the difference between EXPOL ThermaSlab and EXPOL Platinum Board?

EXPOL ThermaSlab is a cost effective way to insulate a building and meet Building Code requirements. EXPOL Platinum Board is a premium product with superior R-value.

Is EXPOL ThermaSlab water resistant?

The closed cell construction of expanded polystyrene (EPS) ensures it resists any adverse effects of water. EPS board used in skillion roof spaces holds its shape, structure and thermal properties for the life of the building.

How effective is EXPOL ThermaSlab for thermal insulation?

Made of 98% trapped air, EPS demonstrates excellent thermal insulation properties.

Is EXPOL ThermaSlab environmentally friendly?

EXPOL ThermaSlab requires very little raw material for manufacture making it so efficient that it will save up to 200 times its own resource in energy savings. All EXPOL expanded polystyrene (EPS) products are 100% recyclable.

Does EXPOL ThermaSlab give off toxic fumes?

In the event of a fire, the level of toxicity of EPS is no greater than timber. EPS does not off-gas hydrogen cyanide or hydrogen chloride. No CFCs or HCFCs are used in the manufacture of EXPOL Platinum Board.


EXPOL products are available at a number of leading building products stores. Find your nearest stockist here.

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Other Skillion Roof Insulation products which may be of interest

EXPOL Platinum Board

Fast Facts
  • Easily insulate narrow roof spaces with EXPOL ThermaSlab insulation board.
  • Create energy efficient buildings that require less heating and cooling by insulating with EXPOL ThermaSlab.
  • EXPOL ThermaSlab is available in a variety of grades and thicknesses to suit the application.
  • With a well-established reputation for durability, expanded polystyrene (EPS) roof insulation will not sag, degrade or allow thermal loss over time.
  • A thin, lightweight board, EXPOL ThermaSlab is fast and easy to install.
  • EXPOL ThermaSlab is easily cut to suit purlin or rafter spacings.

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Enquiry Form

General Enquiry

Tel: +64 (9) 634 3449

Free Phone: 0800 86 33 73


105 Captain Springs Rd., Onehunga, Auckland

Tel: +64 (9) 634 3449

Free Phone: 0800 86 33 73


105 Captain Springs Rd., Onehunga, Auckland

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