The allure is understandable. Not only does timber cladding offer a warmth and texture that other materials cannot hope to emulate, but it also changes over time in a way that is aesthetically pleasing rather than unattractive. Finally, it performs for decades without complaint if done correctly. But to do so requires a number of decisions that will have a profound effect on the finished product in both form and function.
Species Selection Changes Everything
Western red cedar is by far the most popular timber for a number of very good reasons. Not only is it naturally resistant to rot due to the presence of oils in the wood itself, but it also remains stable even in extreme conditions of temperature and humidity. Finally, it silvers over time in a finish that is so closely associated with modern design that it is difficult to think of any other timber for the purpose. The downside is that it is very expensive and becoming harder to source in a sustainable fashion. This is causing many to look for alternatives.
Siberian larch is very similar but less costly. The grain is denser and the weathering process is very similar but not identical. The initial finish is a lovely golden brown that gradually silvers over time. Because it is harder than western red cedar, it also holds fixings better—a factor that may be important if the timber is to be fully exposed.
European larch is another option that is closer to home and so may offer some advantages in terms of transportation costs and benefits. The downside is that it is not quite so durable as the Siberian version. However, if treated correctly, it is a very good performer for cladding purposes and especially if not fully exposed to the worst of the weather.
Thermally modified timber is a relatively new arrival on the scene but is quickly proving itself to be a very attractive option. The process involves heating the timber in a controlled atmosphere that changes the very fabric of the wood itself. Species such as ash and pine, and even our own homegrown softwoods, become possible candidates for external use. The colour is a very attractive dark brown and remains consistent over time rather than changing in the way that natural weathering does. Then there is the matter of treated and not treated. Pressure-treated wood can add longevity to woods that might not naturally withstand exposure to the elements. However, there is a drawback in terms of appearance, as a greenish or brownish colour is inevitable. Not treated means you rely completely on the natural resistance of the wood and any finish you might add.
The Long View
Well-used, timber cladding provides a building envelope that improves with age, not degrades. The silvery finish of naturally weathered cedar or larch has a depth and character that an installation of brand new materials cannot hope to match. Even with a well-maintained finish, a certain air of “lived in” character will soon be apparent, something no factory-applied finish can hope to achieve.
The trick is to select a material, profile, and finish that works in context, as well as a level of maintenance you’re actually prepared to undertake. There’s no point specifying a low-maintenance weathered finish if the client will have a fit if they see colour change, just as there’s no point specifying a high-maintenance oil finish if you know you can’t afford to maintain it.
If you get those basics right, then timber cladding will deliver something that’s sadly rare in modern building products: a facade that truly ages well.