Condensation and Non-combustibility Considerations in sarking
Pliable building membranes (also known as ‘sarking’ or ‘underlay’) are primarily used as one or more control functions as a water, thermal, vapour or air control.
The new code has two new key amendments for sarking; firstly the NCC 2019 allows the use of sarking (provided it meets the applicable criteria) to be used in non-combustible external wall applications.
Secondly, where a sarking is used for external wall application in building types 1, 2 and 4, it must be vapour permeable for climate zones 6, 7 and 8.
Development Applications and Building Permits approved using NCC 2016 should not be affected by this change, and may use the wall wrap included in the original specification. From the 1st of May 2019, the change will become applicable for Development Applications and Building Permits approved after this date; however this may vary by state and local governing body.
Click here for Fletcher insulation bulletin outlining the key changes in the NCC 2019.