Wood is a remarkable material — infinitely varied, easily workable, biodegradable and renewable to boot. But it does have an Achilles heel: Compared to many other building materials, wood is quite perishable. Hence, using wood in architectural details subject to weather is really asking for trouble down the road.
In spite of this, architects and builders love to lavish their designs with projecting wooden beams, brackets, and other stickwork — a practice that’s only increased with the current revival of woodsy Craftsman-style architecture. But as beautiful as wood detailing looks on the day it’s installed, it’s only a matter of time before it gets walloped by Mother Nature. What’s more, since the quality of sawn lumber is not what it used to be, modern designs using wood are even more susceptible to decay than the original Craftsman buildings were.
Still, if you feel compelled to use lots of wood detailing out of doors, here are a few ways to give it a fighting chance:
- Use generous lumber sizes for pergolas, corbels, projecting roof beams and other exterior wood features. Sun and rain will decay all wood eventually, but heavy timbers will look good longer than spindly ones will. And since anything smaller than a four-by-four looks like a matchstick in the scale of the outdoors, design proportions will benefit too.
- Don’t detail exterior wood structures as if they were furniture. This is a favorite technique of contemporary Craftsman fans, but a shortsighted one. A redwood pergola loaded with fancy joinery may look stunning when it’s brand-new, but after a few years of exposure, all those lovingly fitted pieces will shrink, warp, twist and generally start looking pretty tatty. Therefore, avoid miters and other joints that depend on high tolerances and fussy workmanship. Plain old butt joints, lap joints, tenons or other beefy connections that use a simple square cut will hold up better over time.
- Don’t get too fond of the color of the wood you’re installing, because it won’t be around for very long. Heart redwood, for instance, has a beautiful pinkish tone when freshly cut, but in a few seasons will darken to a rather gloomy grayish black color. If this look isn’t your cup of tea, consider using a semitransparent or solid color stain from the outset (and where appropriate, save a little money on a lesser grade of wood). Using clear sealers or, worse yet, varnishes to try to preserve the color of fresh wood will only get you a bigger maintenance headache — you’ll be finishing and then refinishing from now until kingdom come.
- On horizontal wood surfaces such as decking, the best finish is probably none at all. Clear preservatives tend to wear out quickly in traffic areas, which then discolor in a most unsightly splotchy fashion. Once again, the only way to avoid this dog-run effect is to recoat the whole deck every few years. Since most people have better things to do with their time, a more practical solution is to skip preservative treatment altogether and simply get to like the look of weathered wood.