Getting on Board

Composite decking continues to grow,

but some contractors say the product still needs work.

Source: REMODELING Magazine

By David Zuckerman

Whatever your feelings on composite decking, it's here to stay. The category continues to grow, carving out a larger share of the multibillion-dollar decking market every year. But the pace of that growth has slowed: Where the early years of this decade saw annual market-share gains of 30% (in dollar terms), between 2005 and 2006 composites grew just 18% in dollar terms and in single digits in volume terms, according to John Pruett, area leader for building products at Principia Consulting. Pruett says much of the slowdown can be attributed to a rise in manufacturing costs — Hurricanes Katrina and Rita took out Gulf Coast resin facilities, which led to higher prices. But a rash of product failures and consumer complaints have hurt, too.

Today, manufacturers are offering a greater diversity of composite products than ever before, including different wood-grain looks, colors, railing systems, and accessories; but prices remain high, and many contractors have yet to warm to the material. Though the market for composite rail systems still has considerable room to grow, Pruett says, there is uncertainty about when composite decking will reach a saturation point.

Another key question, Pruett says, is how long building products conglomerates such as Dow, Alcoa, and CertainTeed will continue to compete with the pure play manufacturers that currently dominate the market. Last year, the top three composite manufacturers — Trex, TimberTech, and Fiber Composites — accounted for 53% of the value of the $1 billion composite market.

Manufacturers say that composite decks look better than ever, and homeowners are buying, but many remodelers say they still prefer wood.

HOW MUCH MAINTENANCE?

Composites made huge gains in the early part of the decade by selling consumers on the idea of a maintenance-free deck. That claim, however, proved unfounded: Composites need to be cleaned and, in moist climates, sealed to reduce mold growth. A class-action suit brought by four New Jersey households against Trex resulted in a settlement, the terms of which prohibit the manufacturer from using the phrase “maintenance-free” in its advertising, as well as from claiming that its decks require no sealant.

Manufacturers now readily admit that composite decks must be cleaned and are, depending on the environment in which they're built, susceptible to mold and mildew growth. “It's low-maintenance,” says Trex spokes-woman Maureen Murray. “It's certainly not going to prevent the need for cleaning. I don't think any product that's outdoors could do that.”

Paul Bizarri, vice president of research and development at Timber-Tech, says his company and other manufacturers have made substantial efforts to improve mold and mildew resistance, replacing oak wood flour — which in some cases contributed to mildew growth through the bleeding of tannins — with maple. At the same time, he says, an effort is under way to lower consumer expectations and better educate distributors, contractors, and homeowners about the conditions that promote mold and mildew growth — essentially any climate other than California or the desert West and Southwest — and how to treat growth that does occur. For example, gapping, Murray says, is essential “so debris and water can fall through. Otherwise they accumulate in those little crevices and create a food source for mold and mildew.”

BEND, DON'T BREAK

While mold and mildew might be the foremost concern for homeowners when it comes to composite decks, when you talk to contractors, the conversation doesn't end there. Though composites receive high marks for durability, many remodelers who regularly install them say these products still leave much to be desired, and fall short of wood in a number of areas including look, feel, malleability, and structural integrity.

“We really don't like composites, as a general rule,” says Chaden Halfhill, whose Des Moines, Iowa, company Silent Rivers is a full-service design/build firm that earned a reputation for its high-design decks. “We understand why it exists, but it's not as pleasant to use.”

As a designer, Halfhill finds that the physical properties of composites hinder his creativity because the boards are less easily manipulated to create custom details. “You can't do a horizontal detailing because you need a certain level of verticality for it to support its own weight. And it's a bit harder to manipulate the wood because if you cut it down, its integrity decreases. You're limited by the nature of the material. Structurally, it can only do certain things.”

Sean Leonard, a project manager at Silent Rivers, says he dislikes composites' weight and flexibility, which make the boards difficult to work with, particularly on a hot day when boards are even less rigid. In addition, Leonard says that the lesser structural integrity of composite boards has forced him to adjust some of his standard practices. For example, notching and counter-notching — standard when building posts and rails as well as elevated structures such as pergolas and arbors — actually weakens composite boards.

We like to picture frame [our decks] and then bring the post inside the deck a little ways,” Leonard says. “And if we have double rims, like a flush beam situation, we'll be notching out our posts to the thickness of one of those joists; but if it's a composite post, you can't do that. It's not strong enough. We almost never mount on the exterior of a deck, and we're always going to double, so we always seem to be running into that problem.”

Solutions tend to differ from project to project, Leonard says, depending on the project and the customer's budget and taste. Most recently, he says, creating a custom steel rail system for the deck solved the problem.

Manufacturers are looking to address those concerns, Bizarri says, but face the dual challenge of reducing the weight of composites without limiting structural integrity. Recently, TimberTech introduced chemical foaming — a process common in the plastics industry — to its manufacturing process to reduce the weight of its composite boards.

“Essentially, you're introducing more air into the same space, which lets your product be lighter,” Bizarri says, of the foaming process. “It does affect the structural properties, so the long-term objective is to find properties that are strong enough to meet the needs of the application.”

TimberTech engineers are also working to apply processes used to make the company's composite fencing products, including foaming and inserting metal rods into extruded boards for horizontal applications. “There are challenges with structural integrity, especially in horizontal components,” Bizarri says, “but adding a metal insert with an extrusion process has worked in our fencing, so that's a way we're attacking it.”

High expansion and contraction rates make gapping and joining composite boards unpredictable.

A LITTLE GAP GOES A LONG WAY

Other contractors have run into trouble with the contraction and expansion that composites undergo as a result of seasonal temperature changes. “Composites will expand in summer and contract in winter,” says Kansas City remodeler Dick DeVuyst, owner of high-end deck specialist Outdoor Environments. “The installation technique must account for that. You have to pay particular attention to the temperature when you install it. It makes a difference in how you gap your end joints and butt joints, and how you miter your trim.”

One deck specialist in the Midwest had so much trouble with extreme movement that he swore off composites entirely and now refuses to work with them. The contractor, who asked not to be named because he is still negotiating warranty settlements with several manufacturers, says he lost $250,000 over a two-year period warranting composite decks. One deck he says, “pushed so much that it flattened the downspout completely up against the house — it moved 2 or 3 inches. “If you're going to move a product 2 or 3 inches and it's in wood with nails, you know you're pulling joists and pulling nails and breaking fasteners. It's some major stuff.”

Though manufacturers specify gap widths based on installation temperatures, the remodeler says, different boards may be installed at different temperatures. “If you have a stack of synthetic lumber out in the driveway and the top has been heated by the sun but the bottom's cool from the concrete, and you're pulling it all down that day, every board you put down has a different temperature. So you can gap it all evenly, but when you put it down it expands or contracts different amounts.”

DeVuyst says that he only installs with one composite brand, Trex, because, after years of installing it, he knows how it will react to temperature changes. “I like to stick to one [product] because I know what it does. The worst thing for a contractor like us is to go out to a job two years later and find everything's all out of place because we didn't gap it right.”

Bizarri, acknowledging some of composite's early troubles, places the product somewhere in the middle of its development. “We've made a lot of improvements, and the product will continue to improve,” he says. “Frankly, this category is evolving, and will continue to evolve.”

Leonard, the Des Moines remodeler, for all his dissatisfaction with composites in their current state, says he has faith in the power of the market to force manufacturers to make a better product. “They're going to have to be competitive in the marketplace, or they're not going to be there.” —David Zuckerman writes frequently on construction topics from his home in Brooklyn, N.Y.