New requirements for building timber frame homes in New Zealand have been released in response to the country’s leaky homes crisis.
The Building Industry Authority’s (BIA) design changes, intended to make homes more weathertight, could save an estimated NZ$800m over the next 25 years as a result of not having to repair leaky buildings.
The Weathertightness Solution requirements adopt the “4Ds” principles of water management in buildings – deflection (keeping rain away from sensitive areas using eaves or flashings), drainage (providing paths for water which gets behind cladding), drying (removing water which leaks through cladding, using ventilation) and durability (making sure construction materials are appropriate for their use).
A risk management approach to weathertightness protection will also be introduced, more cladding types will be allowed and extra detail for designing around problem areas such as decks, balustrades and balconies will be required.
The cost impact of changes on a simple brick home will be about NZ$500, while it could be as high as NZ$5,000 or more for a timber frame home.
