EXPOL Underfloor Insulation FAQs

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What are the benefits of EXPOL UnderFloor Insulation over other products?

One of the biggest benefits of EXPOL underfloor insulation panels is that they are rigid, which means they do not sag. Soft, pliable insulation material such as glasswool or polyester has the potential to sag after many years. 

The lightweight, rigid design of EXPOL underfloor means:

  • Underfloor insulation stays in place which ensures a consistent thermal performance as heat can’t escape through new cracks.
  • No need to replace in the years to come and incur expensive stripping and re-installation costs. 
  • Moisture and vermin are unable to enter through newly formed gaps.

Expol is also fire-retardant, water resistant, and non-allergenic.

What is the size of an EXPOL panel?

EXPOL panels are 1200mm long x 60mm thick and available in 3 widths 410 / 470 / 560mm. These are standard widths commonly found in underfloor joists.


How many panels per pack and what is the metre coverage?

Panel Width Panel Size Number of Panel Per Bag Coverage m2
410 1200x410x60 11 per bag Covers 5.41m2
470 1200x470x60 10 per bag Covers 5.64m2
560 1200x560x60 9per bag Covers 6.05m2

To understand how many packs you will need for your project please see our calculator

How do I know what size EXPOL UnderFloor I need?

To identify what width of EXPOL UnderFloor you need simply measure the width between your underfloor joists. EXPOL have developed a colour coded system so that you can easily identify the width required. 

Simply use the EXPOL underfloor ruler which is graduated in a different colour for each width. Hold the ruler up to the joists and measure the cavity width between the joists. If the width intersects the blue you need 560, the green you need 470, the orange you need 410 and the yellow you need 360.

What if the EXPOL panels aren’t an exact fit?

We have cleverly designed the EXPOL underfloor panels to have concertina sides. The concertina cut sides can compress the panel by 2mm each side so that it fits snuggly between the joists. The concertina channel also makes it easy to cut down the panel to fit. All you need to do is run a Stanley knife down the pre-cut concertina sides for a perfect fit.

The concertina design is also an advantage for when the joist width is larger than usual. In this case, a second panel can be easily cut to make up the difference in width.

What is the difference between an L bracket and a Joist Saddle?

EXPOL have developed brackets to ensure that the panels stay secure overtime. Whilst the panel is a snug fit this is recommended to ensure that there is no movement over time and wooden construction does contract and expand overtime. There are two different brackets for the different types of homes:


When fitting panels under an existing floor you use EXPOL L Brackets – these are non-corrosive nylon fixings. Two brackets are used per panel and positioned diagonally at each end of the panel. 


When fitting panels on new floors you use EXPOL Joist Saddle Brackets. The brackets fit over the joist and the panel is dropped into the void supported by the feet of the brackets. Two brackets are used per panel and positioned diagonally at each end of the panel.

When would I use EXPOL silicon adhesive?

Our water-based glue adheres polystyrene to most surfaces. EXPOL UnderFloor panels can be glued in place using this adhesive as an alternative, or in combination with the brackets.

Why do I need to use WireGuard?

EXPOL WireGuard is a waxed paper strip used to separate exposed electrical cables from EXPOL UnderFloor Insulation. It ensures that the plasticiser that surrounds the electrical wires are do not react to the insulation and degrade over time. Irrespective of what underfloor insulation material you choose, we recommend that the precaution to secure electrical wires is taken.

What are the safety measures for installing EXPOL underfloor insulation?

EXPOL is made out of EPS (expanded polystyrene) which is non-irritant and non-toxic. Is also safe to breathe in. Gloves, goggles and face masks are not required to handle EXPOL product itself. We do however recommend that the safety guidelines for protective gear outlined by WorkSafe and other government bodies be followed, as it relates to home repairs and construction sites.

We also recommend wearing gloves when cutting EPS panels with a safety blade.

Prior to installing EXPOL Underfloor insulation and securing all electrical wires with WireGaurd, please switch off your power at the mains. 

Ensure that you fix a sign to the fuse box notifying others. 

We have one here you can download and print

Is underfloor insulation important and does it work?

Underfloor insulation can make a significant difference to the interior temperature of your home. Insulating your home creates a thermal barrier to heat, which assists in keeping your home warm in winter and cool in summer. 

Did you know that a home without underfloor insulation can lose up to 20% of heat in winter, and, also gain up to 20% heat in summer through your floors alone? 

Installing underfloor insulation in your home not only results in a noticeable difference to the comfort of your home, but also has an environmental benefit. A properly insulated home decreases the use of heating and cooling, and therefore reduces the greenhouse gas emissions. This has added benefit of saving you money over time.

How much does underfloor insulation cost?

The cost of underfloor insulation will depend on the following variables:

  • The size of the floor area you wish to insulate
  • The type of material and R value you choose for your underfloor insulation
  • Whether you will require labour to install or whether you do this yourself

To understand the estimated cost of installing EXPOL underfloor insulation, please see our handy pack calculator.

Is underfloor insulation easy to install?

That depends on the type of insulation you choose! EXPOL underfloor insulation is extremely DIY friendly. It is lightweight and easy to handle. EXPOL is also safe to work and non-toxic so won’t irritate your skin like other insulation materials.

We have plenty of video tutorials that detail step by step instructions on how to install EXPOL underfloor insulation.

Which underfloor insulation is best?

When deciding which underfloor insulation is best for your home, you will need to take a few things into consideration. The first would be to consider the construction material of your floors. 

If it is a timber floor, you will need to ensure that the underfloor insulation you choose fits snugly in between the joists. This is very important as heat flows indirectly through your floors and contributes up to 20% of heat losses and gains throughout the seasons.

You will also want to give some consideration to the material of the underfloor insulation. Is it rigid and will it stand the test of time? Or will it sag, lose its thermal capabilities and need replacing in the years to come? 

EXPOL R1.4 is BRANZ Appraised. It is rigid and won’t sag over time, which is one of the reasons we are able to offer a 50-year warranty on our products.

For the health and safety of your home and occupants, you will also want to ensure that the insulation material you use is waterproof, fire retardant and does not provide nutritional value to rodents and vermin. Thankfully, EXPOL underfloor insulation ticks all these boxes. 


What is an R value and why is it important?

An R value is the measurement given to a material’s thermal resistance, or the flow of heat transfer. As R values increase, the rate at which heat flows decreases or slows down, thereby increasing the insulation effectiveness. In other words, the higher the R value, the higher the thermal performance and energy savings.

According to the Australian Building Code, the minimum R value for underfloor insulation is 1.0 in most areas.

How is EXPOL underfloor insulation manufactured?

EXPOL underfloor insulation is an expanded polystyrene product. Expanded Polystyrene (EPS) is a cellular plastic material that is lightweight, hollow and spherical shaped. Made from 98% air, non-toxic and water-resistant, the cellular structure of EPS makes it dimensionally stable and very thermally efficient.

How is EPS made?

Styrene is a liquid chemical structure that is found naturally in many foods such as cinnamon, oats, and coffee. In the manufacturing process of EPS, styrene is produced from benzene and ethylene, and is polymerised (strung together) in the presence of catalysts, usually organic peroxides. 

To create the EXPOL insulation boards, steam is applied to tiny grains or beads of styrene. This steaming process causes the polystyrene to expand up to 40 times its original volume.

What effects does the manufacturing process of EPS have on the environment?

Unlike the manufacturing process for many other synthetic materials, the EPS manufacturing process does not involve the use of ozone-layer-depleting CFCs and HCFCs, nor are there harmful materials present in the finished product. 

It uses less than 0.1% of global crude oil as a feedstock, yet it can deliver up to 200 times its own resource in thermal energy savings. There is also no residual solid waste generated in the production of EPS products.

Is EPS recyclable?

Absolutely! Expanded Polystyrene is 100% recyclable during the many stages of its life cycle. EPS is recycled at collection centres located across Australia. For an updated list, please visit Expanded Polystyrene Australia. EXPOL, manufactured by The Foamex Group work closely with the EPSA – the peak national body for manufacturers and distributors in Australia.

Is EXPOL underfloor insulation flammable?

EXPOL manufactured by Foamex complies with all Australian building standards and has been a popular choice for builders and DIY enthusiasts. Our products have a fire-retardant component built into them. EXPOL is designed to shrink away when exposed to a small flame source, rather than fuel the fire. It is important to note that all products adhere to the strict Australian building codes – we do not support, nor do we manufacture flammable products for building projects.

Our friends in New Zealand show us how EXPOL performs under flame. Watch here

Does EXPOL Underfloor Insulation have a BAL (Bushfire Attack Level) Rating?

The BAL rating is the Australian standard for measuring the risk of a home’s exposure to ember attack, radiant heat, and direct flame contact. The BAL rating determines the construction and building requirements necessary to protect homes in bushfire-prone areas.

As a result, EXPOL as an internal subfloor lining can be used in BAL-rated sub-floor designs and is manufactured with a fire retardant additive to enhance the safety profile. Our high-quality fire retardant aims to lessen the flammability of the material and aid in halting fire spread, offering an extra safeguard for your dwelling.

Is EXPOL made in Australia?

Yes! EXPOL underfloor insulation is made locally in Australia, and manufactured by the Foamex Group. EXPOL is also found in New Zealand, and all products sold there, are manufactured in New Zealand. We are a brand that supports our local communities by keeping manufacturing local.

What makes EXPOL a sustainable building product?

Here a few reasons why EXPOL underfloor insulation is a sustainable insulation choice:

  • It is fully recyclable – reducing environmental waste
  • Excellent insulating properties – reducing energy when heating and cooling
  • Water resistant material – reducing spoilage
  • Comprised of 98% air – resulting in the efficient use of raw material
  • Lightweight – reducing consumption of transport fuels
  • Resilient – reducing product breakage
  • No CFC’s (Chloroflurocarbon) – resulting in the protection of the Ozone
  • Strong and sturdy for long-lasting applications
  • Acoustic benefits
  • Complies with Australian Building Standards