What does R-Value mean? How much do I need?

banner image of man installing wall insulation. Blog post explaining what insulation R-value is.

What to consider when choosing an R-value

The R-Value – or R-Rating of thermal insulation measures how resistant the insulation is to heat transfer. A higher R-value means a higher insulating rating – i.e. a higher resistance to heat transfer. New buildings are general specified at the design stage as requiring a certain R-value.

Photo of a woman with a Knauf Earthwool Wall Insulation pack with an R-value of R2.5

Before recommending the insulation R-value, consideration will be given to things such as the climate zone, (temperature variations, humidity etc) the design of the house including which building materials are used, and the effect of any shading and direct sunlight on the building. R Ratings for insulation will often correspond closely to the thickness and density of the insulating material.

Use the recommended R-Value

If your existing home currently has no thermal insulation installed in the ceiling, then installing insulation of any R-Value will in most cases significantly reduce the amount of heat transfer into your house in summer and the amount of heating which escapes your home in the winter. It’s important to note that doubling your R-value will not necessarily double your energy cost savings. If your home has been specified as needing an R3.0 insulation in the ceiling, upgrading to an R 6.0 will perhaps double the insulation cost, but it’s unlikely that this cost would be saved back by further reductions to your energy bills. As a rule of thumb, we recommend you work off what has been specified, or, on the assumption that electricity prices will continue to rise – you may consider upgrading to a slightly higher R-value. To discuss your recommended insulation R Value needs, please Contact Us at any time.

  • Knauf Earthwool® Roof Batts

    $ 4.45$ 12.02 p/m2 inc. GST
  • Knauf Earthwool® Wall Insulation Batts

    $ 3.01$ 11.44 p/m2 inc. GST



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