Rising damp

Have we learned our lessons from the leaky buildings fiasco?

How far has New Zealand come since leaky buildings started making front page headlines in early 2000?

As a country have we mastered the art of constructing weatherproof buildings yet? Or have we still got a way to go in terms of learning from the mistakes we made with untreated timber, moisture management and liability?

Prendos director and registered building surveyor, Philip O’Sullivan has been on the front line of these issues for the last 20 years.

He gained first hand experience of moisture problems and timber decay as a BRANZ accredited advisor in the late nineties, when he first saw a pattern of building problems that he knew would lead to what’s now known as the leaky building issue.

This led him to develop and promote the principles and practices that would eventually be introduced into the industry to ensure greater weathertightness, solving the leaky home issue. He worked hard to educate and eventually influence industry, the government and the public.

Still more work to do

Heading towards retirement now, Phil says we’ve come a long way, but there will still be nasty surprises in store for some home owners.

“In terms of timber framing, that’s been resolved since 2005 more or less and it got better after that. We’ve gone back to the past and are using boron treatment.

“That was a treatment that was developed in the 1950s, post war and that proved very, very good for a number of years. We lost it for a few years, and that was a disaster.

“So there’s a whole range of houses and buildings with non-durable timber inside them. But anything built post 2005 has got good durable timber; there’ll be the odd exception. Generally, as of today, the durability of the timber is very good.”

Twelve years of building without treated wood

Phil says houses built between 1993 and 2005 would have a “question mark” about whether adequately treated timber was used to build them, and therefore may not be durable.

He hastens to say that weather tightness isn’t water tightness.

“It’s not about keeping water out, it’s about managing moisture, because water will always get in. It will always find its way through and therefore it’s a case of letting it drain and evaporate before it can do damage, and making sure the parts it gets to are sufficiently durable while they dry out.”

He explains that in the case of timber, having it treated gives you a massive difference in how it performs.

If it gets wet for a day or two and dries out it doesn’t matter. Where as if it’s untreated timber it can rot and carry on rotting. “Every time it rains, there’s decay, it starts up again and away it goes.”

The other major progress he points out was building in drained and vented cavities. However, not everyone realises how important they are, yet.

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