Energy Rating Basics

Defining the terms

The standard method of attaching weatherboard or sheet claddings to wall frames for decades has been to wrap the outside of the wall in a sarking or building wrap then screw or nail fix the cladding straight over this, allowing no sort of ventilation cavity. The wrap used to be a foil, but in recent years vapour-permeable wraps have become the norm. This is still the minimum required standard in the building codes as of NCC 2022.

The alternative method of fixing requires the addition of cavity battens. These are 20-35mm battens which get fixed over the wall wrap. The cladding then gets fixed over the battens, leaving an air-space which provides ventilation.