Design, not the timber, leads to leaky buildings, says expert

Dr John Straube told an Auckland University symposium yesterday that the biggest problem was modern designs which exposed building seams to wind and rain - simple things such as not having eaves or proper flashings on windows, flat roofs and enclosed decks.

Better design of wall systems would ensure that water which got in could also get out.

Dr Straube, who has a joint role with the University of Waterloo's civil engineering department and school of architecture in Ontario, said using untreated timber in a modern building in which moisture and rain were not controlled was like using a canary in a coalmine.

"You put some untreated timber in a building, so you found out [about leaks] sooner," he said.

Moisture problems in buildings had occurred in various countries with both wood and steel framing.

Untreated timber was also used in many countries. But the qualities of such timbers varied. Dr Straube thought the best of untreated New Zealand pinus radiata was equal to the worst of Canadian timbers.

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