I can’t count the times I’ve wandered out onto a southern exposure deck and found it cooked and grayed to the point of structural instability. Many times, these homes have been vacation rentals, which explains why some of the regular maintenance tasks slipped through the cracks over the years. Paired with deep water weathering, boards can gray on the surface and suffer from deeper structural damage below the surface.
Once upon a job site, I actually stepped right through one such grayed board. Solar weathering breaks a deck down in a different manner than weathering by moisture. When a deck sits under the intense rays of the sun, over time the supple, strong structure of the wood succumbs to the drying power of ultraviolet radiation. Having installed various kinds of decks in intensely sunny climates, I’ve discovered a few methods and materials which can keep a deck in good shape for the long haul.
The Weathering Challenge of Direct Sunlight
UV rays are the active agent of solar weathering. As I mentioned above, these rays literally cook and dry out the cellular structure of wooden decking boards. Thankfully, only the fibers near the surface of the board are affected, but UV damage still leads to an unattractive surface and opens the deck up to moisture infiltration. This domino effect can lead to more serious damage and structural instability, as with the deck that I stepped through. As you might expect, decks that are oriented to the south are the most intensely weathered, followed by decks exposed to the intense western sun.
Solutions to Direct Sunlight on Wood
There is actually quite a lot that can be done to address the challenges brought by direct sunlight on wood decking. While the decking boards themselves can be cared for, the environment of the deck can also be altered to keep the deck from undue deterioration. All in all, there are few steps that I almost always take in sunny situations:
- Frequent Application of Good Stain: While some woods are weaker in the sun than others, all woods benefit from a stain with heavy tint. It’s the tint in the stain that protects the board from UV radiation, and generally, the heavier the tint, the better. Spending money on the best possible stain and applying it every other year is a pretty simple way of keeping a deck in good condition.
- Shades, pergolas, vines, and other coverings: Another method of deck protection, that also adds beauty to your deck area, is to provide some shade. Awnings, roller shades, and bamboo blinds can all be used to provide shade (and create a cozier deck). If clients don’t mind waiting a year or two, I love building pergolas or trellises, and training a variety of vines up and over the deck. I’ve found that a thick covering can lower the temperature by several degrees.
The Best Decking for Direct Sunlight
There are a few good, time-tested materials that fare well under the hot sun. The list below contains the ones I think survive the sun best. Types of wood that cope with sun well are usually dense, with tight grains, which keeps them from splitting, cracking, and splintering.
- Teak: Teak is actually better known for its water resistance. It’s fairly ubiquitous all around the equator for its resistance rot and mold. However, unlike the also-popular hardwood ipe, it handles intense sunlight with vigor. With a good oil or stain, teak will retain much of its dark color for some time as it gracefully grays. However, if any maintenance is skipped, teak will very quickly begin the graying process.
- Eucalyptus: Endemic to Australia, eucalyptus trees produce another dense, tight-grained board that does not readily split. It’s also highly water and pest resistant due to its high oil content. Even without its protective bark, eucalyptus has proven itself highly resistant to UV rays. The drawbacks of using eucalyptus are that it’s relatively rare and expensive, is so hard that it has to be pre-drilled, and is generally sold in random lengths, leading to lots of extra work when it comes time for installation.
- Acacia: Also known as locust, acacia has been used around the sunny Mediterranean for centuries to make furniture, pergolas, tool handles, decking, and even houses. Like the other woods on this list, acacia requires a good sealing, and even a lightly tinted stain will go a long way in warding off the sun.
- Fully Capped Composite: As far as sun-loving decking goes, this is the new kid on the block. A modern material comprised of recycled materials, this decking is designed to resist the elements, though some types do that better than others. One line of composite decking was actually developed to deal with the intensely sunny climate of South Africa, where there’s an average of 10 hours of sun a day. Look for composite decking with a full capping (that’s the protective substance that seals the board) that has UV inhibitors built into it. The benefit of composite is that while even the most solar-resistant wooden boards require regular staining and oiling, fully capped composite decking doesn’t any of that maintenance to keep the boards in good shape, structurally and aesthetically. This characteristic makes composite a great decking choice for beach houses, as well as homes in sunny climates. The latest versions of composite are getting more and more realistic as well, and you can now even get composite decking that looks like ipe for that tropical hardwood look without the inevitable fading.
I’m a big believer in composite as the best decking for direct sunlight, but it’s important to understand that not all composite boards are of equal quality. The earlier versions of composite decking had difficulty with the sun, losing their color and having the capping material peel off of the board. The best, newest versions of composite decking contain UV resistant compounds within their capping material. This has created a decking board that won’t gray or fray under the rays of the full sun.
I’ve been able to use all of the materials listed above and more in my building career, including white oak and red cedar. If wooden decks are conscientiously maintained, they may last up to two decades. If well shaded, perhaps even more. Most of the advanced composite decking I’ve put in, though, isn’t yet 15 years old, and with no sun-protecting maintenance performed on them, they’re as strong and beautiful as the day they were installed. That’s an outcome that takes quite a bit more work with a material like teak or acacia.
With composite decking though, as with anything, it’s important to pick a quality brand. At the top of my list is Infinity Decking, manufactured by Fortress Deck. They make a unique, bamboo-based composite that does all of the things I mentioned above–stays strong and beautiful and resists fading. Fortress also produces a wide range of other innovative building materials, so if you’re in the market for fencing, railings, or ornamental hardware, take a look at their full catalog.