How much does Underfloor Insulation Cost?

The true expense of underfloor insulation isn’t just measured in dollars but also in the effort required for installation. Investing in high-quality underfloor insulation and ensuring it’s installed meticulously is essential, as it impacts the overall effectiveness and longevity of the insulation. Choosing superior products can seem costlier upfront but pays dividends in the long term by providing enduring comfort and energy savings.

This makes the initial investment and the installation process crucial — not just a one-time expense but a foundation for a lifetime of comfort in your home. Ensuring the insulation is perfectly installed maximizes its efficiency, reducing ongoing energy costs and enhancing the living environment sustainably for years to come.


DIY installation of underfloor insulation is an effective way to save on labor costs, offering a manageable project for those inclined to hands-on home improvements.

While it’s not considered a technically difficult job, it does require a willingness to engage in some manual labor and navigate tight spaces beneath your home. This effort, however, can lead to significant cost savings as you eliminate the need to hire professionals.

By investing your time and energy, you not only reduce the initial expenditure but also enhance your understanding of your home’s thermal dynamics, potentially leading to better maintenance and efficiency of the insulation over time.

Next Steps:

If you aren’t sure if underfloor insulation installation is for you, check out the DIY Guide where we show you do to achieve a professional result.

Professional Installation

Opting for professional installation of underfloor insulation does come with a higher upfront cost, but it can be a practical choice, particularly for those who may not have the time or physical ability to undertake the installation themselves.

Professional installers can complete the job quickly and efficiently, saving you considerable time and ensuring the insulation is installed correctly for optimal performance.

This is especially beneficial for those who prefer a hassle-free process without the physical demands of crawling in tight spaces or handling installation materials.

Next Steps:

After 20+ years of installing underfloor insulation, we not longer provide that service.  However we have partnered with a number of professional organisations across Australia to provide professional installation.   

Connect with insulation installers near me.

How Much Underfloor Insulation Do I Need?

Are you wondering how much insulation you need to insulate an area of your home? We’ve got you covered. 

This Easy-to-Measure guide is designed to support you in measuring and calculating the amount of packs required to cover your space.

This makes the initial investment and the installation process crucial — not just a one-time expense but a foundation for a lifetime of comfort in your home. Ensuring the insulation is perfectly installed maximizes its efficiency, reducing ongoing energy costs and enhancing the living environment sustainably for years to come.

How to Measure My Home’s Floor Area? An Easy-to-Measure Guide

  • Consider your home from a bird’s eye view and divide it into manageable shapes. (If your home is a square or rectangle, you can calculate the entire area in one sum.)
  • Measure the area of each shape by multiplying their length by their width, this will give you the square meterage (m²) for each section.
  • Add each shape’s area together to find the total area of your home.
How to Measure Your Home Floor Area
How to measure joists for insulation cost and installation

What is a Joist?

A joist is simply the timber that runs directly underneath your floorboards.  

The measurement you need is the distance between one joist and another.  In this case – it is 430mm wide THEN ADD 20mm to the joist width.    

Why should I add 20mm??  
It is so much better to have your insulation a little wider than the space to allow to ease of installation.  An explanation of the installation process can be found here   


For a joist spacing of 430mm you would want to order 450mm wide insulation (this is the general joist spacing in Victoria).

For a joist spacing of 410mm, you would want to order 430mm wide insulation (this is generally the joist spacing in NSW, ACT, SA and QLD). 

But there are exceptions to this, so please pop under the floor and measure the distance.  

What if My Joists Spacings are Different? 

If your joists are different to these, you can either – trim your insulation,  or go to the Turn and Tear method – which is how professional installers cater for variable width joists

What is a Joist “Centre”

Builders generally talk about joist centres – which is just the centre of one joist to the centre of another.  Conveniently, this is exactly the width of insulation you should order for a perfect fit.  

So now you should have the width of insulation that you need for your home. 

Which Insulation Brand is the Right One for Me?

With the right width of insulation, you can then work out which brand of insulation you would like to use
Click here for more information about the different products available.

We have done the research, so you don’t have to.  After 20+ years of insulation experience, we don’t see the point in offering every product (some of them really aren’t useful choices for underfloor insulation – so we don’t recommend them – or sell them).  We only offer the best products for underfloor insulation here:  

How Many Pack of Insulation Will I Need?

Once you have decided which product to use, just click on the product name on the ready reckoner.  It will tell you how many packs of insulation you need based on either  building squares (which is an imperial measurement and no longer used in Australia – but some people still talk in “squares”) or in square metres (which is the standard measurement that is used in Australia).

You will be taken to the where the latest price will be displayed. 
Enter the number of packs that the Ready Reckoner has indicated that you need and the online store will calculate the cost for you. 

What is in a Pack of Insulation?

Each manufacturer has a different number of rolls of insulation per pack – it will either be 2 or 3 rolls. 
So please check the specifications on the Products page carefully to ensure you select the correct width and the correct number of packs 

How Much Will Underfloor Insulation Cost?

It depends upon the area you need to insulate and the product that you choose. Please be aware that the price of insulation MAY fluctuate, so check on to get the latest pricing per pack 

To calculate the cost of your underfloor insulation, either: 


Example 1:

  • You need to insulate 100 square metres 
  • You are based in Melbourne and have a suitable vehicle to collect your order from Preston. 
  • You have decided to use Value Poly R2.5 450mm wide  
  • The ready reckoner has told you that you need 14 packs 
  • So at $71 per pack x 14 packs = $994 
  • Delivery is free as you are collecting from Preston.

Example 2:

  • You need to insulate 150 square metres 
  • You are based in Sydney and would prefer to have your insulation delivered to your door.  
  • You have decided to use PolyMax R2.5 430mm wide  
  • The ready reckoner has told you that you need 17 packs 
  • So $150 per pack x 17 packs = $2,550
  • Delivery is $175, so total price is $2,725.

If you need help placing your order, or have any questions, please contact us on 1300 326 627, jump on the chat at or contact us here