For the Best Decking for a High Altitude, Look for UV-Resistant Materials

Best Decking for a High Altitude

Composite can be a perfect fit for a high altitude location if it’s durable enough to stand up to the increased UV exposure.

Designing structures for high altitude settings requires using materials able to adapt to the more strenuous climatic conditions. While wooden decking is more quickly broken down by the higher intensity UV rays at altitudes, with the right maintenance regime, it is possible to keep it in good condition for some time. I still have a couple loyal clients who invite me for weeklong working vacations every year to take care of the decks of their mountain vacation homes. The sun is so intense up there that the maintenance often does need to be that often and that involved.

However, I found there are some other materials that are able to handle the challenging weather conditions of high altitudes without as much maintenance as wood. Having spent a few seasons working for clients up in the mountains and the high desert, I can appreciate the value of reduced maintenance, and I like to think that I’ve also discovered the best decking for a high altitude. Here’s what I’ve learned through trial, error, and research.

The Effects of a High Altitude on Your Deck

For many of us, the first thing we think about when we hear the words “high altitude” is the cold, followed closely by snow. But in many ways, the sun is an even more powerful adversary the higher one climbs. It’s no great secret that UV rays literally dry out and cook materials over a long enough time span (think of your skin burning in the sun). Here’s why a high altitude is hard on your decking:

  • UV Rays Are More Intense: This is mainly so because, for every 1,000 meters in elevation gain, exposure to UV rays increases by 10%. If the local area is both mountainous and sunny, this effect is magnified. The effect is also stronger the closer one is to the equator.
  • Materials Break Down More Quickly: This increased exposure to UV rays increases the rate at which materials subjected to this radiation are broken down. UV rays weather materials by weakening and breaking down chemical bonds. One of the materials UV breaks down in wood are its lignins, which are important to maintaining wood’s structure.
  • Colors Fade More Quickly: One of the most noticeable effects of the way the sun breaks down chemical bonds is the fading and loss of a material’s color. This means that with extended time in the sun–particularly at high altitudes–wood grays, paint fades, and sealants give out.

The Best Decking for a High Altitude and How to Protect It

In my building work, I use two main materials for decks–wood and fully-capped composite. The strategies of protection for the two of them vary greatly. Protecting a wooden deck is a matter of selecting the best possible stain, paint, or sealer for the situation. Protecting composite decking is an exercise in picking out a brand with the most innately protective elements. Here’s how to keep both of these materials looking great at high altitudes. I’ll also talk about what I consider the best decking for high altitudes, and why.

How to Protect Wood from UV Rays

For many years, the most common decking material in my practice was certainly wood–cedar, redwood, pressure treated, ipe, or otherwise. These are a couple of the usual methods for keeping a wooden deck healthy, no matter which of these woods it’s made of.

  • Opaque Finishes: Finishes that are opaque, such as solid stains and paints, are the most successful at blocking UV rays from reaching the wood. The more tint there is in a stain or paint, the greater the protection it provides will be. These opaque finishes vary in how often they’ll need to be reapplied. Their longevity usually depends on whether they are oil-based or water-based stains. Of course, the relative merits of oil-based and water-based stains is a long discussion unto itself, but in general an oil-based product will last longer and work better than a water-based one.
  • Transparent Finishes: Some homeowners and builders choose a wood with the idea of showcasing its natural finish. When this is the desire, transparent or mostly transparent stains are used. Since these don’t have any pigment, they allow UV rays to penetrate into the decking board. If sun damage is a concern, this isn’t a particularly good option. However, when clients are adamant about this, I make a compromise by finding an oil-based stain with a small degree of pigment in it. Still, I don’t recommend this path for high altitudes, as the sun will deteriorate the wood more quickly than it should and the wood will require more frequent recoating.
Protecting Composite Decking from UV Rays

While protecting a wooden deck involves selecting the best possible protective coatings for the job, protecting a composite deck is a matter of picking the best possible version of composite decking, as this kind of decking material doesn’t require paints, stains, or finishes. So what should you look for in composites for your high-altitude deck? There are a few features you’ll want:

  • Fully Capped Boards: One of the great advancements of composite decking was the addition of a protective capping material which keeps the core board safe from the ravages of sun and moisture, preventing chipping, swelling, and warping. Initially, most decks only had the capping on the top deck surface. However, this did not prove to be enough to protect a deck from the elements. And while the surface is the most important part of the deck to protect in a high altitude situation, you’ll likely be getting lots of fog and snow as well, which can cause issues with moisture even on the underside of the board. For this reason, fully capped is the only way to go–it’ll make your decking water resistant as well as UV resistant, from any angle.
  • UV Inhibitors: Pigments similar to those found in some of the best stains and paints are simply “baked into the cake” of a good capping material. With the best products, this is done in a way that has significantly reduced color fade on many of the decks I’ve put in during the past few years.
  • A Warranty: Composites don’t tend to be dirt cheap, so when you’re making an investment in a good quality decking system, it makes sense to choose one with a good warranty. This is especially important when you live in a location that can be hard on building materials, such as thousands of feet above sea level. Some decking manufacturers have 25-year limited warranties that can give you peace of mind about your investment.

I never used to build composite decks, and until recently I certainly wouldn’t have considered them for a high altitude location. But advances in the design of high-quality composite means that it’s now an excellent substitute for wood that takes much less work to keep beautiful than wood does. A decking board with a resin cap, manufactured with plenty of UV inhibitors, can last for years while looking just as good as it did when it was first installed. While I still use both wood and fully capped composite decking to build decks at high elevation, when clients are interested in eliminating the work and expense of long-term maintenance (as is often the case with vacation or second homes), I steer them in the direction of the latter. If they choose composite, one of my first recommendations is Fortress Deck, as their boards use one of the most advanced capping materials on the market, designed to resist even the sun at high altitudes. Fortress decking doesn’t mold, mildew, or absorb moisture, either. After we get the deck installed, and other projects arise, I sometimes recommend taking a look at Fortress’ other products, like railings and fences. All of these building products are high quality and extremely durable, making them great choices for high altitudes.

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