Is over-insulating a home possible?

wall insulation batts in a house

A correctly insulated home should save energy and costs, whilst creating a comfortable environment all year round. It’s important for homes to strike a balance between under-insulation and over-insulation to achieve this state. This is why cities and regions around Australia are classified into ‘climate zones’; all new buildings require a certain grade of wall insulation batt quality (dictated by the zone,) to prevent temperature leaks, and ensure energy efficiency. But what about old homes?

Energy efficiency has historically been overlooked when designing and building homes in Australia; it wasn’t until 1993 when a Nationwide House Energy Rating Scheme was introduced. Insulation is a key part of a house’s energy efficiency.

What does insulation do?

So, what do roof, floor and wall insulation batts do? Well, heat naturally flows from warmer areas to cooler areas. To simplify the science, insulation can keep your house warm in the Winter months by reducing the escape of hot air from the house to the colder air outside. Meanwhile, in summer, it prevents the hot air from coming in and traps the cooler air inside.


Whilst it is possible for a house to be over-insulated (and we will get back to this point later,) it is far more likely that Australian homes are under-insulated. 24% of electricity use in Australia is from residential buildings. In residential buildings, electricity is used for water, cooking, appliances etc. but shockingly, a study in 2014 found that space conditioning such as heating and cooling takes up 50% of electricity usage in Victorian homes. Proper insulation should bring this percentage down dramatically, meaning increased comfort and massive savings on your electricity bill. So, while insulation may increase the upfront cost of a home, over ­­the long run, it will save money if completed correctly.

Luckily, we know a few people that are experts in Insulation batts in Melbourne. Our team at Insulation Essentials has over 30 years of experience in the construction industry and understands how important environmentally friendly and energy-efficient home design can be.


Now to the big question, we know houses can be under-insulated, but can they be over-insulated. The answer is yes, but it is not particularly common. There are two downsides to an over-insulated house, the first is cost. One of the key benefits of a good installation is it saves you money in the long run. If you have spent thousands of dollars on extra insulation batts to not much extra benefit in terms of energy efficiency, then your house could be considered over-insulated. The other downside is mould. Moisture can get trapped in between the insulation layers if your home is too tightly sealed and no air can escape. The moisture combining with the fibres of the wall insulation batts/ timber/ plaster and other materials can lead to mould build-up. If there is not enough airflow this can lead to a lack of ventilation and lower quality air being circulated through the household. The key to insulation is about finding an effective balance.

The R-Value

So, how can a homeowner find out if they have struck the right balance and have the correct insulation? Well as mentioned earlier, your house will be in a dedicated ‘climate zone’, Melbourne and the Port Phillip region, for example, are a part of climate zone 6. This means that insulation across houses in these areas should have an R-value of 2.25 in the flooring, 2.8 in the walls, 4.1 in very-light coloured roofs, 4.6 in light coloured roofs, and 5.1 in dark-coloured roofs.

If you suspect your house’s insulation is below standard, or over-insulated, the best method of finding out is via an insulation audit from a professional. An insulation professional can help you determine the R-value of your current roof, floor and wall insulation batts or rolls and whether you need extra installed or removed. It is recommended to consult with a specialist to assess your home insulation before making any DIY adjustments in case you end up wasting money or over-insulating your house: generating poor financial and health outcomes.

If you need a floor, roof or wall insulation batts or rolls installed in Melbourne, whether you are building a new house or completing renovations; consider purchasing some of our quality insulation products. Insulation Essentials offers a range of batts and rolls available in a variety of R-values to suit whatever projects you require. Find out more by visiting our store.

If you require some insulation in Melbourne, then please give us a call on 03 8339 7111. You can also contact us by filling out the enquiry form found on our website.