How to protect your wood deck from the suns harsh rays

August 2024 · 5 minute read

My wood deck sits in the sun all day with no shade. It’s now treated lumber and requires sealing every other year. I’ve tried lots of different sealers all with the same results. I’m tired of all the work, and I need some wood deck resurfacing ideas. I wonder if you have any experience with the exotic hardwoods like tigerwood. My husband and I are also thinking about composite decking, but it’s quite pricey. What has been your experience with wood decks, and what would you do if you were me? — Diane K., Morgantown, W.Va.

You’re in the same boat as many homeowners. In fact, I was in this boat up until a year ago. Allow me to share 40 years of experience in 1,000 words.

I’ve built countless wood decks. They’ve been all sizes, shapes, and I’ve used all sorts of different wood species. The exotic hardwoods are some of the hardest to install because many of them are so hard and dense, you have to pre-drill all the fastener holes. Keep that in mind if you do decide to use that material. By all means get a sample piece and play with it to see how hard it is to install.

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My guess is that a majority of the wood decks out there have treated wood decking and railing systems. Currently, treated wood is the least expensive material to use.

Though treated lumber may resist wood rot and insect infestation, its downside is that it can’t resist the punishing effects of the sun’s ultraviolet (UV) light. What’s more, wood is hygroscopic, and it expands and contracts with respect to moisture content.

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If you don’t seal treated lumber with some coating, the UV light will destroy the natural color pigments and the lignin that bonds the wood fibers together. Just as our skin needs sunscreen to prevent sunburn, so does wood.

Paint is perhaps the best UV protector for treated lumber, but it lies like a film on top of the wood and peels easily. Many solid-color stains are really just paint, so don’t fall for that marketing trick. If you’ve ever had a painted deck that has peeled, you’ll only make that mistake once, as it’s a nightmare to refinish and re-coat.

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Many deck sealers have the consistency of traditional penetrating wood stains, and one would think that they’d soak into the wood fibers. They do soak in, but I’ve discovered that many of them are also film formers.

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Some of these stains leave a thin hard resin coating on the top of the wood, and this thin layer tends to peel in two or three years. If you do stain, it’s best to get one with a medium colored pigment. The pigment particles sacrifice themselves to the UV light before it gets to the wood fibers.

Over time water can also destroy treated lumber. This is why you need to keep treated lumber sealed so that water can’t penetrate it. If water is allowed to soak into lumber, it causes the wood to swell. When the wood dries out the wood shrinks. This movement creates tiny cracks in the lumber.

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The next time it rains, the water can soak in deeper using the cracks as a pathway. The expansion and contraction movement is amplified because more of the wood is expanding and contracting. The cracks get wider and deeper, and eventually the treated lumber starts to resemble a 50-year-old fishing pier.

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Even the best deck sealing products don’t hold up well against the harsh UV light. I did my own extensive testing of many major brands of deck sealers about four years ago. Some failed within 90 days. The best one lasted two years before it finally started to peel a little bit. By the end of year three, the best performing sealer looked bad enough that it was time to strip it and start over. It’s a huge amount of work to strip or sand a wood deck and reseal it.

I believe this is why many homeowners have gravitated to the composite decking and railing systems. At this point, these materials have been around for almost two decades. As with all materials, the first and second generations were not the best. Sometimes it takes a few attempts until you finally get it right, and I believe now a few of the composite decking manufacturers have worked out the kinks.

Last year I was tired of my decking and failing wood-railing system. It needed work, and I had gotten to the point that I no longer wanted to deal with periodic sealing. I went with a major brand decking that offered a capped system. The core of my composite decking is a blend of wood fiber and plastic, but the top wear surface and the edges are capped with a virgin vinyl that’s both embossed and has coloration to simulate real wood graining.

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My wife is a harsh critic of anything synthetic in building products. She has never liked any of the composite decking materials until she saw this one. The samples in your hand or small mock-up decks at the lumberyards don’t look that appealing, but once the product is installed on the deck and you look across it, it does look realistic. My wife approves of the composite we have and loves to sit on our deck in the afternoon.

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My new railing system is also care-free, and it was easy to install. I would recommend that you take a serious look at all the top-of-the-line composite deck and railing products and see which one appeals to you. You won’t regret switching over. Be sure you select one that has a hidden fastening system. I don’t have any visible fastener holes anywhere on my deck or railing.

If you have an asphalt shingle roof, check out Tim’s new book “Roofing Ripoff.” Tim discovered a way to extend the life of your roof for decades. Go to: RoofingRipoff.com. All of Tim’s past columns are archived for free at www.AsktheBuilder.com. You can also watch hundreds of videos, download Quick Start Guides and more.

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