Timberapex - Choosing Timber Species for a Hot and Humid

People assume you can build a timber frame anywhere and it will behave the same. Then they watch a spotted gum post stay dead straight through a wet season while a softer species behind it twists like a wet plank. Humidity is the part of the equation most homeowners never think about until something starts moving. Around Cairns we swing from humid forty degree days to cool dry nights, and the timber has to live through both without gapping at the joints. Hardwoods like ironbark and spotted gum are dense, and density is what buys you stability. They take longer to dry, they cost more per lineal metre, and they are harder on the saw blades, but they hold their shape. Blackbutt sits in the middle and costs less, which is why it turns up so often in floors and framing. We check moisture content on every load before it leaves the yard, because a beam that was dried badly will move no matter what species it is. For saunas and bathhouses the answer goes the other way. Western red cedar is soft, light and handles heat without checking, and it stays comfortable to sit on. You would never frame a house from it. Timber choice is not about picking the best species overall, it is about matching the species to the job: structure, lining, decking and benchtops all want different qualities. One practical tip before you buy anything. Ask for the grade and the moisture reading in writing, and ask whether the timber was milled locally or shipped in. A supplier who cannot answer those two questions is not the one we would use on a home that has to stay straight for forty years.

Choosing Timber Species for a Hot and Humid Climate