Retrofit your deck with composite

I'm a little embarrassed to admit this publicly, but here it goes: I'm abandoning wood in exchange for a modern upstart. When I built the 800-sq.-ft. wraparound veranda on my house a dozen years ago, I used 2x6 eastern white cedar for the decking. The finish lasted better than most: three years in sunny spots and more than five seasons in the shade on the north side. But then the inevitable set in–a little peeling here, some grey wood peeking through over there and even some scratches. I'm definitely not into a barnboard deck, so refinishing was a must.

I stripped the deck, refinished the wood and restored that great look. This happened a couple of times, in fact. Trouble was, the ongoing refinishing process took more effort and money than I expected. A lot more. Which brings me to my confession: I pulled up all that perfectly good cedar from the good-as-new superstructure, gave the cedar away to a good cause, then replaced it all with composite. I may be embarrassed, but I'm also relieved.

Composites are a 50/50 blend of reclaimed wood fibres and recycled plastics. They offer finish-free deck performance, with nothing more required than an occasional wash. Although I did consider composites in the mid-1990s, when I built my veranda, the expense and appearance scared me away. But when you consider that the price you pay for composites gets you out of all the requisite finishing and refinishing, then the economics are more reasonable. Add to that the fact that better-looking composites are coming out all the time, and the deal becomes more compelling–even to a traditional wood guy like me.

Floor transplant

Before you decide if a deck-board transplant is for you, take a hard look at the condition of the joists, beams and posts you currently have. I was pleased to see that the design features I'd incorporated to speed up water drainage and drying of the joists, beams and posts had worked perfectly. Except for spiderwebs and old leaves, the underlying superstructure of my deck is as good today as when it went up in 1995. Not a speck of rot anywhere.

I like everything about the 2x6 cedar decking except the maintenance. That's why I chose a solid composite to mimic the thickness of cedar. Hollow, extruded composites are lighter in weight and less expensive than solids, but they don't look as nice in my book because you can't rout edges and ends. I opted to use Trex solid composite because I've used it before with good results. The plastic comes mostly from recycled grocery-store bags, and the wood fibres come from ground-up hardwood shipping pallets and furniture-factory scraps.

Starting over

The most tedious part of replacing deck boards is getting the old ones off, and for this job I had the help of an eager worker. My nine-year-old son, Joseph, asked to take on the work when I began my Trex transplant. I never guessed how fast he'd become after some practice.

Joseph's forte is unscrewing Robertson deck screws that have been weathered for a dozen years, with heads that carry the residue of two or three refinishing campaigns. "I definitely prefer an impact driver instead of a drill because the driver grabs screw heads much better than a drill," Joseph says. "I only clean screws that the driver bit won't grab on the first try." I gave Joseph a scratch awl to clean the screw heads. The pointy tip is perfect for the job. Sharpen the awl on a bench grinder as required to keep it in shape.

Installation station

You won't have spent much time installing composites before you discover that they're much more flexible than real wood. This feature means you need to pay attention to keeping them straight as they are fastened to the structure. It's especially important to get the first row correct, and for this you can't beat a tight string. Pull it from one end of your deck to the other, just slightly higher than the thickness of the deck boards. Put your first course of boards down, align them to the string, then anchor them straight. You might think that subsequent rows of boards will automatically be straight too, but that's not necessarily so. Before every second or third row goes down, take a look along the entire edge at deck level, from one end to the other. Have a helper pull the wayward board in or out until it's as straight as possible, then lock it down. I use a BoWrench and rubber mallet to wrestle deck boards into alignment. The work is easier than with real wood because composites don't have the same internal springiness.

As you work, understand that expansion can be an issue with composites. Unlike wood, composites don't change size much with fluctuations in moisture. Shrinking composites aren't likely to be a problem, but expansion caused by heat might be. It's essential that you include sufficient gaps between boards and at their ends. The amount of space required varies with different products, and with the temperature of the day you put the boards down. Ignore this detail and you could get a buckled, bumpy deck on hot days.

Most people don't anticipate how much work goes into maintaining wooden decking. They're surprised, then overwhelmed enough to live with grey, peeling decks. Just because you've opted for a wooden deck in the past doesn't mean you need to stick with it until all the lumber is compost. Composites offer a way out, even if they'll never be quite as classic as the newly finished real thing.




Invisible anchors

With material as expensive and long-lasting as composites, you should consider an invisible fastener system. Although a clean, fastener-free surface is much nicer than one riddled with screw heads, there are two problems that most invisible fastener systems have in common. First of all, most are expensive. They're also much slower to install than face-driven screws. The FastenMaster system I used isn't any cheaper than others, but installation is very fast compared to others. It's based on plastic clips that anchor to the underside of the deck boards with small, flathead woodscrews that are included in the box. Flip the deck board over, then drive longer screws through an angled hole in the edge of the clip and into the floor joist. Clips on the next board interlock with those on the ones you just screwed down. From then on, you simply drive the long, angled screws into the outer edges of the deck boards only. Each clip includes a flange that ensures consistent spacing. Also, since the screws that anchor the clips to the underlying floor joists are angled, they automatically pull the deck boards tight to the previously installed row. Each clip also raises the deck board 3/16" off the top of the floor joists, ensuring fast evaporation of rainwater.

Plugged in

There comes a point when even the best invisible fastener system can't be used. In my case, this was at the outer edge where the bullnosed deck board overhangs the edge of the deck, and on the last course of boards along the wall of the house, where there isn't enough room to drive the angled anchoring screws. My solution for both these situations is the same: counterbored galvanized deck screws driven down into the underlying floor joists, then covered with tapered plugs made from Trex. I used a plug cutter to make the plugs and glued them in place with weatherproof adhesive.

When making the plugs, you need to cut strips of the material so they're as thick as the plugs will be. When you cut plugs this way on the drillpress, they'll break away from the rest of the material as they're cut, with the wood grain pattern on the bottom surface. Stop the drillpress, pull out the plug with your fingers, then start the machine and cut another plug. This process takes longer than cutting wooden plugs from a thicker block (then cutting them free afterward as a group), but it's the only way to preserve the superficial wood grain on composites.

Added touch

Routed details add so much beauty and they take so little time. (In my opinion, these deck details are not used often enough.)

I have three routed profiles on my deck: a 1 1/2"-thick bullnose on all overhanging edges, a 45º chamfer on all board ends, and a 3/16" radius milled onto long edges, to re-establish the factory-rounded profile whenever it was cut off while making boards narrower on the tablesaw.


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