The ultimate goal of any homeowner is to achieve year-round comfort with a well-insulated home. This comes with the added benefit of cutting cooling and heating bills, and in turn, reduces greenhouse gas emissions.

While it is possible to over-insulate, most Australian homeowners under-insulate rather than overdo it. If you think you’re in that category, don’t rush out and add more layers of insulation, because you will reach the point where too much insulation starts to have a negative effect – financially, environmentally, and for your health.

Can you spend too much money insulating your home?

When used correctly, installing insulation should save you money in the long run. But if you overdo it, eventually your house becomes so well insulated that adding additional material isn’t going to help. Any minimal insulating benefit you might gain is offset by the cost of installing it.

There is an ideal level of insulation for any geographical region around the country. Once you reach that point it is better to add heat or risk spending money on materials and not recouping your investment in a reasonable period or over the life of the house.

Is it possible to over-insulate your house?

Heat Loss Detection of the House With Infrared Thermal Camera

Heat Loss Detection of the House With Infrared Thermal Camera

Yes! It is possible to over-insulate your house so much that you block nearly all ventilation, and it simply cannot breathe. The whole purpose of home insulation is to seal your home’s interior to keep it warm in cold weather and cool in hot weather. But if it becomes too tightly sealed with too many layers of insulation, moisture can get trapped inside those layers. And that is when mould starts to grow.

Over-insulating your house also means it is harder to achieve a consistent temperature throughout the home because heat can become trapped. Additionally, blocking ventilation means you and your family will be breathing in lower-quality air, potentially leading to health problems.


It’s all about the R-Value

“R-Value” is a rating system that indicates how well a layer of insulation reduces heat flow. The greater the R-Value, the more effectively the building material or piece of insulation will resist the conductive flow of heat. This means that insulation with a high R-Value provides better thermal insulation.

It therefore follows that highly thermal insulation is good for your home, but each time you add another layer of insulation, that latest layer is doing less work because there isn’t as much heat flowing through it to begin with. The first few layers already provide most of the insulating, so the new layers don’t provide as much benefit no matter how high their R-Value is.

All building materials have an R-Value; and when choosing your building materials, it’s important to note that each different type will have its own specific thermal qualities. These thermal qualities will either increase or decrease the effectiveness of your insulation. The thickness of the material plays the greatest role in determining how effective it is, but the density and thermal mass will also play a part.

Consider the environment when choosing insulation

Properly insulating your family home has a positive environmental impact. By making your home more energy-efficient, you reduce the amount of energy your family consumes, as well as the amount of energy you waste.

But just as insulation costs money to produce and install, there’s also an environmental trade-off that happens when it’s manufactured. With reasonable amounts of home insulation and making good insulation product choices, that trade-off works in favour of the environment. There is a net reduction in energy usage.

However, if you’re over-insulating your home, you are effectively consuming those materials without any real environmental offset.

How do I know if I need more or less insulation?

To determine whether you should add more insulation to your home, you first need to find out how much insulation you already have in your home and where it is located.

You can hire an expert to assess your current insulation and they can recommend any changes and organise the removal or installation. If you prefer a DIY approach, you can undertake a review yourself by determining what type of insulation you have, and the R-Value and thickness of that insulation.

If your insulation strategy includes underfloor insulation – which it should if your home features raised timber flooring – then it’s well worth considering a quality underfloor insulation product that conforms with the Australian standard and offers an R-Value of at least 1.4.

Just remember – over-insulating your home is a very real thing, no matter which insulation products you choose to install. It could pay to speak to home insulation professionals before making your purchase.

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