Underfloor insulation is an important part of having an energy efficient home. It helps to keep your floors warm in the winter and cool in the summer. It also reduces draughts and improves indoor air quality, which will help to save you money on heating and cooling costs. 

Insulating your floors reduces noise transfer from outside and can stop allergens such as dust, pollen, bugs and smoke from entering your home. Additionally, it has the potential to increase the future resale value of your home. It is also essential for anyone looking to increase their home’s efficiency and reduce their carbon footprint. 

And while adding underfloor insulation will save you between 10% and 20% of heating and cooling energy, the single greatest benefit of underfloor insulation is that it will transform the temperature of your floor from being the external temperature to being the internal temperature.  And that is what transforms the feeling of comfort on your floor.


Is Underfloor Insulation Important?

If you’re living in an elderly and poorly insulated weatherboard home or a brick veneer home on stumps, both with uninsulated timber floors, then the answer is a resounding YES.  Unfortunately, this is the norm for thousands of families, particularly in the temperate climate zones of South East Australia.   

How Big a Problem Is it Meant to Solve?

Not so much one problem, but a series of interconnected facets of energy use and comfort.

1. Expensive Heat Loss and Heat Gain

Victoria’s SEAV researched the average winter heat loss and summer heat gain for one of these blighted homes. That research is now part of the Australian Government’s ‘Your Home Technical Manual’:


And there you have it. Whatever the season, 10 – 20% of the energy you put into trying to make your home comfortable just disappears through the floor.

And in these days of galloping increases in gas and electricity prices, not to mention mortgage interest rates, who can afford that for long?

2. Timber Floors are Bad Insulators

Whether your house has floorboards or floor panels, all you have between you and the outside temperature is a thin layer of wood. And while wood is a reasonable insulator in thick log cabin walls, it does a poor job as a 19 mm floorboard, offering no more than an R value of 0.7.

If you’d like to explore in more detail the R value aspect of timber floors and what can be achieved through underfloor insulation, ecoMaster has you covered.


3.  Draughts 

Draughts are also known as uncontrolled ventilation. 

If you go back to the SEAV graphic, you’ll see that poor thermal performance is not the only disadvantage of timber floors. Over time, the timber floorboards tend to shrink away from each other and create gaps for draughts. If the house moves as well, these gaps and the draughts they create can be pronounced. And uncomfortable. And expensive to offset.

Air leakage, both out of and into the house, amounts to an energy loss of 15 – 25% in winter and 5 – 25% in summer.

If you install ecoMaster’s recommended polyester underfloor insulation and you do it the “ecoMaster way” so it’s tightly held to the underside of the floorboards and securely fixed to the floor joists, then:

  • many of access points for draughts will be cut off
  • condensation and mould growth caused by cold air entering the living space will be reduced.
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4. Outside Noise

In the same way, as properly fitted underfloor insulation reduces the channels available for draughts, it reduces them for external noise as well. Your living spaces will feel more like libraries.


5. Temperature Regulation and Comfort

Underfloor insulation promotes greater temperature stability throughout the home throughout the year- fewer cold spots, fewer hot spots, and more comfort.


Are There Any Other Advantages to Insulate more than just under the floor?

When considered against retrofitting wall and roof insulation, there are three advantages: 

  • providing you have enough headroom, fitting under floor insulation is relatively straightforward and perfect for the DIYer. Sure it’s dirty – and occasionally claustrophobic – but for a relatively modest sum and a weekend’s work, it’s done and dusted.  For good. 
  • unlike attic insulation, there’s no risk of falling through ceilings.
  • unlike wall and window retrofits, there’s no “making good” of the surrounding areas afterwards so costs are contained and predictable.

Is Underfloor The Whole Story?

No – if your home has little or no insulation, there’s obviously more you can do if you have the time and money to invest. 

But as far as making the most of the benefits underfloor insulation on its own brings to your home, you should seal draughts inside the house as well.

Insulating under your floors will stop most of the draughts seeping through floorboards, but complete peace of mind and wallet will only come when you seal the gaps between floorboards and between floorboards and between floorboards and skirting.

It’s far more an investment of time and patience than money. ecoMaster always recommends draught proofing – whether around openings in walls, ceilings or, as we’ve discussed, floors – as the simplest, cheapest first step in any DIY energy efficiency upgrade.

If you’d like to know more, here is a great guide on How to Draught Proof Your Home Like a Pro.

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People Also Ask: 

⇒ Is Underfloor Insulation Necessary?

The most recent changes to the National Construction Code (NCC) 2022 require all new build homes to reach a minimum 7 star rating.  This means that “whole home” approach to energy efficiency is required.  Whilst not strictly mandated, it would be almost impossible to achieve 7 stars without insulation under your floors for homes with timber or steel framed floors. The new NCC will commence on 1 May 2023, with a transition period to 1 October 2023 to assist the industry with its transition.

⇒ Does Underfloor Insulation Make Much Difference?

Yes – without underfloor insulation your floor will be the same temperature as outside.  With underfloor insulation, your floor’s temperature will be closer to your inside temperatures.  Underfloor insulation will make a noticeable difference in both the comfort and energy efficiency of your home. 

⇒ Is Underfloor Insulation Effective?

Underfloor Insulation helps to reduce heat loss from your home, making it easier to maintain a comfortable temperature throughout the year and reducing your cooling and heating costs.  Additionally, underfloor insulation can help reduce noise transfer from external sources into your home.

⇒ Does Underfloor Insulation Help in Summer? 

Yes, underfloor insulation can help in summer by providing an insulating barrier between your home and the heat outside.  Underfloor insulation will assist in retaining your air conditioning inside your home, as well as significantly reducing draughts that come through the floor.  In extreme cases of gappy floorboards, you may need to seal your floorboards as well as installing underfloor insulation.  

⇒ Where Do I Find Out More About Underfloor Insulation? 

The team at ecoMaster have put together a MasterClass on Underfloor Insulation.  This is based on 20 years and installing 20,000 homes with underfloor insulation.  We were installing underfloor insulation even before it became “a thing”.  

That MasterClass can be found here. It discusses:

  • the pros and cons of different types of insulation
  • how to choose insulation with the most robust qualities (water, fire, compression)
  • the best installation techniques plus videos on how to achieve the best outcome for your home whilst keeping your insulation securely in place and keep rodents out! 

There is also a whole specialist website dedicated to underfloor insulation.  It can be found here

⇒ Does Underfloor Insulation Really Work?

Yes, underfloor insulation does work. It helps to reduce the amount of heat lost from a home in winter and helps to retain your cool air conditioning in summer.  As a broad generalisation, the biggest user of energy in your home is heating and cooling and underfloor insulation will reduce the amount you need.  Underfloor insulation will also help you create a more even temperature distribution throughout your home.  In 20 years of installing underfloor insulation, we have not had a single client who wished they had not had the insulation installed. 

⇒ How Important is Underfloor Insulation in Australia? 

If we’re looking at this from just a Regulatory viewpoint, it would be impossible to build an Energy Compliant home, on stumps, without underfloor insulation.  

From a residents’ viewpoint underfloor insulation is essential for keeping Australian homes cool in our scorching hot summers and cosy in the coldest of winter.  

An effectively insulated underfloor helps to keep your heating and cooling bills low.  Moderating indoor temperatures also reduces the risk of asthma by reducing thermal variation in your home.  Allergies may also be reduced by the increased control of draughts that allow allergy triggers in your home (such as dust and pollen). 

⇒ Is Underfloor Insulation a Good Idea?

Yes, underfloor insulation is a good idea. Underfloor insulation helps to reduce heat loss in winter and heat gain in summer from and to your home.  Reducing the need to heat and cool your home will also reduce your energy bills and carbon emissions.  A surprising side effect is the reduction in outside noise coming into your home.  Finally, it adds an extra layer of protection for people who suffer from asthma (by reducing thermal variances that can trigger an attack) or allergies by reducing dust, bugs, smoke and pollen gaining access to your home.

⇒ How Effective is Underfloor Insulation? 

Underfloor insulation is a very effective way to reduce energy costs in your home. Sustainability Victoria have shown that it can reduce the amount of heat lost, and gained, through your floor by up to 20%, resulting in significant savings in energy bills. 

Additionally, underfloor insulation helps maintain a consistent temperature within your home, making it more comfortable for your family. The effectiveness of underfloor insulation also depends on factors such as how well the rest of your home has been protected from the outside elements.  This would include effective draught proofing (please – not door snakes!), roof and wall insulation, as well as shading and window treatments. 

⇒ When is the Best Time to Install Underfloor Insulation? 

Any time of year is a good time to install underfloor insulation.  

  • Installing in cooler months:

Generally this is the busiest time of year to install underfloor insulation as the majority of the population recall just how cold it can get and seek to find ways to get warm. This increased demand can lead to shortages of insulation as well as staples (the preferred fixing method).  As a resident, you will probably feel the impact of underfloor insulation more significantly in winter.  But, installing underfloor insulation during winter can be miserably cold and unpleasant.  Take a friend. 

  • Installing in hotter months: 

Generally this is a quieter time of years to install from an insulation manufacturing viewpoint, so shortages of insulation are less likely.  Underfloor insulation can prevent hot air from entering via floorboards, making your home more comfortable in summer. Having said that, most people look for air conditioners in summer and forget about trying to retain the coolth.  Being under a floor in the summer is gloriously cool. Take some tunes and enjoy this cool time with a friend. 

What’s Next?

We hope this article has helped explain the basics around underfloor insulation that can be installed during the construction phase, or retrofitting after a home has been built.  Installing the appropriate level of insulation is a major step on your energy and thermal efficiency retrofit journey to make your home more comfortable all year round, reduce your costs and carbon emissions.   

Next, explore some easy ways to Install Underfloor Insulation.

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