Let’s Talk About R-Values

Whilst we’ve briefly talked about how insulation batts are rated, there’s actually a lot more to the equation. Insulation, such as glasswool, depends on stopping heat flow. Whether that be keeping the warm weather out and keeping your house cool, or, keeping the warmth in your home when the weather outside is cool.

The R-value is used to represent each insulation type’s thermal resistance – the higher the R-value, the better it is at insulating. Today, we’re going to be having a look at R-values in depth – as well as some other elements that factor in when improving your home’s thermal resistance.

The ups and downs

There are actually three different ways that insulation is rated: up, down and total R-value. The up R-value – also known as the winter R-value – concentrates on how effective the insulation is at keeping heat within your home and is mostly applicable in winter when you need to keep your home as warm as possible.

The down R-value – otherwise known as the summer R-value – does the opposite of the up R-value. More relevant during the summer and warmer seasons, this specific R-value is a reflection of how effective insulation is at keeping heat out of your house.

The most commonly shown R-value, however, is the total R-value and is a combination of both the up and down values. These come together to give you the total thermal resistance of the batt or roll. Unfortunately, it then gets a bit more complex when you account for factors such as thermal bridges and other materials’ R-values.

Minimum R-values

Different areas will have different climates which means that the minimum R-value that your home must meet will shift. The climate zones are rated from one to eight – with one being the hottest and eight the coolest. For example, Melbourne is in climate zone six predominantly, with the rest of Victoria ranging from anywhere between six and eight.

This means that the minimum total R-value will have to be 2.8 for your wall insulation, 2.25 for your floor insulation and anywhere between 4.1 and 5.1 for your roof – depending on if it’s a dark or light colour. You can find the full table of minimum R-values for all climate zones in Australia here.

These are just the minimum values, however, and you can still opt for higher values which will increase your home’s thermal efficiency. You should also know