Douglas fir gets nod in leaky homes rules

Southern forest owners are claiming a partial victory over a rethink on regulations to stop leaky homes.

A new building standard, due today, is expected to allow douglas fir to be used on internal framing after all.

The original proposal from the Building Industry Authority and Standards New Zealand had required all timber inside and outside a house to be chemically treated as protection against leaks and rot.

This was met with outrage by forest owners in the south, as douglas fir cannot be tanalised. About half of the country's 104,000ha of douglas fir, worth $500 million, are in Otago and Southland.

Forest managers of Ernslaw One Otago and Blue Mountain Lumber said the standard would mean douglas fir could be used in "low-risk situations" such as roof trusses and interior walls.

But they said the proposals for exterior walls, which will require external wall framing be treated, were poorly thought through.

"There is no need to have treated timber where there is a good second line of defence in the form of drained and ventilated cavities or, as in the case of weatherboard, where there is natural ventilation and drainage."

They said most problem houses had claddings without cavities to drain water away, inadequate window installations, and inadequate eaves to protect walls against driving rain.

The logical way to deal with this was to require drained and ventilated cavities, or state that where these were not in place, timber was treated.

- NZPA