A comprehensive guide to underfloor insulation

31 May 2021

Home insulation DIY projects often focus on exterior walls, ceilings, and other parts of the house, but one part of the house that can easily get overlooked in insulation projects is the flooring.

When looking to insulate your home to make it more comfortable and economical year-round, while also adding value to the property, it pays not to overlook underfloor insulation and to address how the space under your floors is affecting the comfort of your home.

What is underfloor insulation?

Like other forms of insulation, underfloor insulation provides an effective barrier to the flow of heat through suspended timber sub-floors and helps reduce your reliance on heaters in winter and air-conditioners in summer. Such artificial heating and cooling methods add to your electricity bill while contributing to greenhouse gas emissions.

Does underfloor insulation actually make a difference?

When installed correctly and when quality products with high R-values are used, underfloor insulation certainly makes a difference in terms of making your home more comfortable naturally year-round and reducing your electricity bills.

It’s worth noting that even if the rest of your home is insulated, without underfloor insulation your floors will still be letting in air draughts and allowing heat to leak out. And underfloor insulation can also provide acoustic advantages for your home by dampening the sound of footsteps on your wooden floors.

The various types of underfloor insulation

There are four main types of underfloor insulation products. Each one uses different kinds of materials and methods to deliver underfloor insulation for your home.

  • Foil Faced Insulation

A rigid insulation panel featuring a fire retardant expanded polystyrene core covered with an aluminium layer of foil on both sides.

  • Glasswool Underfloor Insulation Batts

Glasswool batts feature millions of tiny air pockets to effectively slow down the flow of heat. Made from recycled glass materials.

  • Polyester Rolls

Polyester rolls are a type of bulk insulation that traps billions of air pockets within their structure to break up the heat path. Made from recycled plastic materials.

  • Expanded Polystyrene (EPS) Foam panels

Expanded polystyrene rigid foam boards are a cost-effective and energy efficient underfloor insulation solution to effectively make your home more comfortable year round. Certain EPS foam board products are uniquely designed to be easy to install.

How underfloor insulation adds value to your home

Installing underfloor insulation can add long-term value to your home by making it a more cost-effective, efficient, and comfortable place to live. Here are five ways quality underfloor insulation adds value to your home.

  • Reduce drafts: By creating a barrier that wind cannot pass through.
  • Prevent heat loss: By reducing temperature change.
  • Reduce unwanted moisture: By creating a ‘vapour barrier’ that prevents moisture gathering on the underside of raised wooden floors.
  • Pipe protection: By providing added protection when the water in your pipes reaches freezing temperature.
  • Make summers manageable: By naturally controlling the temperature inside your home.

Underfloor insulation as a DIY project

Depending on what type of underfloor insulation product you choose, you may be able to install it yourself as a DIY project. One such example is expanded polystyrene foam panel products. Installing this type of underfloor insulation is simply a matter of:

  • Measuring the distance between your joists.
  • Cutting the panel to size if required.
  • Sliding the panel between the joists and pushing it so it’s nestled flush with the floorboards. 
  • Fixing supplied fittings in place at the panel’s corners.

If you’re planning on installing your new underfloor insulation as a DIY project, it’s worth choosing a product that is non-toxic, such as rigid expanded polystyrene boards.

How effective is underfloor insulation?

Underfloor insulation helps keep your home cool in summer and warmer in winter by creating a barrier that shields your home from air that flows up through your floorboards. If you have no insulation at all under your floor, you’ll be surprised by how much change you’ll feel with underfloor insulation. Using a high R-value underfloor insulation product coupled with the correct installation method, you’ll benefit greatly from investing in underfloor insulation.

The cost of underfloor insulation

Compared to other methods and materials for insulating your home, underfloor insulation is an affordable solution, particularly when done as a DIY project. Some underfloor insulation providers have an insulation calculator on their website that can help you determine the materials cost for your underfloor insulation project.

Where to buy underfloor insulation?

Underfloor insulation products can be found at most hardware stores, such as Bunnings, Home Timber & Hardware, and Mitre 10. In some cases, underfloor insulation can also be ordered direct from the supplier.

Trusted for more than 20 years, Expol Underfloor Insulation is the ideal rigid board for insulating under timber floors. It is easy to install, available in four convenient joist widths (560mm, 470mm, 410mm, 360mm), and a popular option for DIY underfloor insulation projects.

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