Insulation is one of the hidden heroes of modern home design and can make all the difference when trying to build a comfortable, energy-efficient home. Given this hefty responsibility, though, it’s important to choose the right types and specifications for your climate. Sound overwhelming? It doesn’t need to be. Even an understanding of the basics can make that choice a lot easier, or at least help you keep up in conversations with your builder. Let’s get into it.
WHAT DOES INSULATION DO?
To understand how insulation works, it’s first important to remember that heat naturally travels from warm areas to cooler ones, until the temperature in both spaces is the same. Insulation works to slow this process so that indoor temperatures remain stable for as long as possible. Most insulation does this by creating air pockets that slow the transfer of conductive and convective heat, while others use reflective surfaces to block radiant heat. Both methods help maintain a comfortable indoor temperature and reduce energy consumption.
TYPES OF INSULATION
Different types of insulation are designed to be installed in different parts of the house. Let’s have a look at the most common types:
Bulk Insulation
Bulk insulation uses pockets of air to slow the transfer of heat in both directions. If it’s hot outside it’ll help stop heat from seeping inside, and if it’s cold outside it’ll help stop the indoor heat from escaping. It’s versatile and comes in several forms:
Batts or Blankets: Made from polyester, fibreglass or wool, these rectangular batts or blankets can be pushed between the studs in walls and ceilings. Polyester batts, such as those from Polymax, are our favourite for their durability and sustainability. They’re made from 80% recycled materials, don’t cause skin irritations during installation, and maintain their shape over time. Fibreglass is a more affordable option, but it can irritate skin and doesn’t last as long. Wool is another option that’s eco-friendly and flame-resistant but offers slightly lower thermal performance.
Rigid Board: Common in cavity brickwork or under suspended slabs, rigid boards are made from polystyrene or similar materials. They’re pest- and water-resistant and maintain their shape better than batts.
Spray Foam: This polyurethane-based foam is sprayed into cavities where it expands to form an insulating layer. It’s great for tricky spaces but can be costly and requires professional installation.
Recycled polyester batts.
Rigid board in cavity brickwork at Ardross Street.
Reflective Insulation
Reflective insulation has an aluminium foil surface that reflects radiant heat. It’s highly effective at blocking this heat from entering the home but will do little to stop heat from escaping. For this reason, it’s great in warmer climates and most often used in conjunction with bulk insulation.
Anticon
Anticon is a reflective blanket that’s installed under metal roofing. It’s not legally required in Australia, but we consider it a non-negotiable in all Arklen projects. This is because it helps prevent condensation and protect the rest of the roof structure against moisture damage. It also provides the last barrier against the heat of the sun on the roof.
Colorbond roofing being installed on top of Anticon roof insulation.
A BIT ABOUT R-VALUES
R-values measure how well an insulation product can resist heat flow. The higher the R-value, the better it is at insulating. In Australia, the National Construction Code specifies minimum R-values depending on your climate zone. In Perth’s climate zone (zone 5), for example, walls must have a minimum R-value of 2.8, while ceilings require at least 4.1. If you want a better performing home you can, of course, exceed these minimums.
These days, one of the best ways to test how well your insulation will perform is with a thermal assessment. The specifications of your home are input into a modelling software that will then predict the thermal performance of your home. At least one thermal assessment is required in Australia to ensure your design meets the minimum 7-star efficiency rating. It can, however, be used to model different insulation types and R-values to help you find the most optimal combinations.
TRADE SECRETS
Now, let’s dive into some of the trade secrets that we’ve picked up over many years in the building industry:
Don’t compress it: Squashing your insulation may seem like a good idea, but this will only reduce the number of air pockets that are required to make it work. Always ensure batts fit snugly without being compressed.
Consider acoustics: Insulation isn’t just for temperature control—it also reduces sound transfer. You can even buy acoustic batts, which are denser than standard ones and will reduce both noise and heat transfer. These can be great to reduce the sound of traffic or simply just to improve privacy between rooms.
Insulate your pipes: In multi-storey homes, plumbing pipes can act as conduits for heat transfer and noise. Insulating them, or using pre-insulated pipes, can significantly reduce these issues.
Align batt sizes with stud spacing: Standard batts are designed to fit between common stud spacings—typically 450mm or 600mm on centre (measured from the centre of one stud to the next). Planning your stud layout around these sizes ensures a snug fit without needing to waste time trimming the batts.
Double up if needed: If you can’t find insulation with the exact R-value you need, don’t worry. Layering two lower R-value batts (e.g., two R2.5 batts to achieve R5) works just as well.
MAKING THE RIGHT CHOICE FOR YOUR HOME
Just as with any other material, your insulation should be chosen with consideration for the cost, performance, and long-term benefits. Investing in high-quality materials, such as polyester batts, might cost more upfront, but will likely pay off later down the line thanks to its durability and improved energy efficiency. As always, your builder should be able to explain your options and help you choose the insulation types that will be best for your particular home. And we hope this guide will make those conversations easier for you to understand. If you have any questions, though, don’t hesitate to reach out and we’ll be happy to help.