R1.5 Wall Insulation


Is R1.5 insulation sufficient?

Investing in a higher R-value will help protect you from the burden of increasing energy prices. In cooler climates a higher R-value is generally recommend, even if your energy report requires a minimum of R1.5 wall insulation.


Insulation for home renovations

If you are recladding or replastering your home then you should consider installing insulation in your walls. The key is not to leave gaps, as this will greatly reduce the effectiveness of the insulation.


Choosing a brand

The most important factor to consider when buying insulation is not the brand but the R-value of the product. The higher the R-value, the better the resistance to heat flow and the greater the insulting effect. This will lead to higher energy savings.



R1.5 Insulation for Walls

Insulation companies in Australia have adopted two main standard widths of insulation, 430mm wide and 580mm wide. This is because the timber frames in most Australian homes are spaced at either 450mm or 600mm ‘centres’ – from the centre of one timber to the next. Assuming the house framing is spaced at either of these two dimensions, when installed your insulation will fit snugly between the joists or studs.

However not all houses are built to this standard and this creates extra work for insulation installers.

Dealing with Irregular Joist

Below are some examples and tips for dealing with irregular or non-standard joist spacing.

  • Less than 400mm between timbers – use 430mm wide batt, trim away excess
  • Between 430mm and 550mm – use 580mm wide batt – trim away excess, consider using wide pieces to fill gaps
  • Move than 580mm between timbers – use 580mm and add extra strip along side, or cut the batts sideways and install as short pieces.

And here’s another tip: Should you find yourself with some bags of 430mm wide insulation required for a 580mm space, simple cut the batt neatly down the middle, and install as two pieces. The length of each batt is 1160mm, so cutting it in half will give you two pieces, 430mm high X 580mm wide. Click here for more DIY tips.