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 that the thicker the actual insulation product is, the better it will be at insulating.

Another factor to consider is that the materials your home is built from, such as brick or weatherboard, will also have their own R-value – which is combined with the insulation’s R-value to meet the required minimum.

R-values in building materials

Whilst nowhere near as high as glasswool insulation batts and rolls, for example, materials such as solid brick will still have an R-value. When calculating how much thermal resistance your home will have, you’ll be taking into account both the insulation and building materials and combining them to calculate the total R-value.

Weatherboard walls, for example, have an R-value of only 0.45 and cavity brick walls are around 0.5. As you can see, insulation is absolutely essential as common building materials do not have the thermal resistance to keep you warm in the winter and cool in the summer.

Thermal bridging

Thermal bridges are an example of something that can negatively affect your home’s thermal resistance. Essentially, thermal bridges are areas in your home that allow heat and energy to escape. This could be due to two connecting materials of low thermal resistance or even damaged insulation.

There are three different types of thermal bridges that can occur in your home:

  • Repeating thermal bridges – which are almost-identically common bridges that occur throughout your home and are generally due to the design of the house.
  • Non-repeating thermal bridges – these often occur when there’s a gap in the outer walls, roof or general thermal envelope of the building.
  • Geometrical thermal bridging – is the result of the shapes that the design of the home implements.

Thermal bridging can mostly be remedied either completely or as much as possible by installing insulation strategically in areas such as cavity walls or under new sidings.

Looking for glasswool insulation?

Insulation Essentials are premium insulation suppliers operating in Melbourne. We stock a wide range of insulation products – such as glasswool – in our online store in varying R-values so you’ll be able to pick the right insulation product to suit your home.

Our highly knowledgeable staff will be able to help you select what’s right for you if you’re unsure and are also able to deliver and install the insulation for you.

If you’re looking at purchasing some glasswool insulation, then please call us on 03 8339 7111. You may also contact us via the enquiry form found on our website.