R-value measures thermal resistance and represents an object’s resistance to heat. It’s a way of measuring how well insulation can stop heat flow – whether transferring out of your home in winter or into your home in summer.
The higher the R-value, the greater the resistance to heat transfer, the greater the insulating effect, and the greater the energy and money savings.
How do I calculate the R-value?
To calculate the R-value, you add the materials together that make up the barrier from outside. For a suspended timber floor, you add the R-value of the floor, the R-value of any floor covering like carpet, and the R-value of the underfloor insulation. Different products with the same R-value will provide similar insulation performance, regardless of thickness or the type of material.
For example, timber floors have an R-value of around 0.7 and will be the same temperature as outside. If you add carpet, you can add around another 0.3 to bring the total to 1.0. If you then add Expol underfloor insulation, which has an R-value of 1.4 or 1.8, you come up with a total of 2.4 to 2.8.
Sustainability Victoria recommends that floor insulation have an R-value of at least 2.0, with a minimum requirement of 1.0, for the Victorian climate.
What are climate zones?
A climate zone is a category that groups different geographical areas into zones based on factors such as average temperatures, humidity, and rainfall. These and other weather patterns help determine the level of R-value insulation required in a building in each climate zone.
Australia is divided broadly into eight Climate Zones, ranging from the hot, humid areas in northern Australia to the alpine regions of the southeast.
The climate zone will impact the type of insulation you require, but you must also consider other issues, such as the type and layout of the building, building materials, aspect, shading, and more, to determine your desired R-value.
How do I use R-value to choose underfloor insulation?
To choose underfloor insulation for suspended timber floors, determine the R-value required for your specific climate zone. In colder climates, a higher R-value is required to prevent heat loss through the floor, while in milder climates, a lower R-value may suffice.
Next, consider the insulation materials available and their respective R-values. Common insulation products for suspended timber floors include polystyrene insulation like Expol, fibreglass batts, foil insulation, or spray foam insulation. Calculate the thickness of the insulation needed based on the R-value of the material you choose, added to your flooring and floor covering.
Proper installation is crucial for maximising the effectiveness of your floor insulation. Ensure the insulation fits snugly between the joists without gaps or compression, as these can significantly reduce its thermal resistance.
What is the best underfloor insulation for timber floors?
One of the most popular choices for underfloor insulation, expanded polystyrene foam panels are cost-effective and energy-efficient underfloor insulation that will make any home with a timber floor more comfortable all year round.
Expol foam underfloor insulation by Foamex is a user-friendly, DIY home insulation system crafted from lightweight yet durable expanded polystyrene. It offers a cost-effective solution for enhancing your home’s comfort and energy efficiency by creating a thermal barrier to prevent heat from entering in summer and escaping in winter. Suitable for new and existing homes, including pole houses, Expol ensures year-round protection from extreme temperatures.
Made from high-quality, Australian-manufactured expanded polystyrene, Expol includes flame retardant properties and is free from CFCs. It is designed to fit snugly between timber floor joists, with concertina cuts on both sides, allowing for up to 20 mm of compression. Non-allergenic, safe, and easy to install, Expol Underfloor Insulation is widely available across Australia through various stockists.
Where to buy Expol DIY underfloor insulation
Expol products are available at leading hardware stores and other selected outlets nationwide.
Expol Black R1.8 is currently only available in Victoria and South Australia. Buy Expol online here or at Bunnings and other leading hardware stores.
Please contact us directly at 1300 AU FOAM if you require further information.
