Vinyl and plastic ‘wood’ gaining in popularity
by Owen Yost, Landscape Architect

For the last several years, an ever-increasing number of companies have been selling plastic (or vinyl) lumber and semi-finished products. The mega-home improvement stores are even getting in on it. It’s often recycled, and is meant to be used in place of real wood — primarily outdoors. (Although they are somewhat different chemically, "vinyl" and "plastic" are grouped together here, since many of the more-common attributes are identical.)

Plastic lumber is sold in typical lumber dimensions, 2x4, 2x6 etc. Many stores even sell finished plastic and vinyl products such as fence sections, arbors, planters and benches — made to look just like wood. Typically, real wood is used outside for decks, fences, boardwalks and so on. However, even if you like the way wood looks, you may want to explore the use of plastic for a project that will be wet frequently. You see, the one big advantage is that it doesn’t rot.

Since its creation in the ’80s, plastic lumber has undergone quite a few changes, after a very shaky and feeble start. Unfortunately, impressions made back in the ’80s still persist. Now, it has many big advantages over real wood, but it has drawbacks too.

Typical wood for outdoor use may contain preservatives, which may be harmful to the environment. Yet, without this chemical preservative, most untreated wood will rot in a relatively short time. Often, rotten wood isn’t replaced in a timely manner, which is why there are so many sagging fences and things around here. The naturally resistant types of wood, such as redwood and cedar, will last a lot longer outdoors (although they rot eventually, too), but they’re more expensive, and may not be available at lumber yards anyway.

Plastic lumber doesn’t rot. This means you won’t have to replace any weak, rotten boards. It won’t splinter or crack, either — even in direct sunlight. (I should point out that high-quality wood that is properly installed and maintained should not split or crack for many years.) So you’d better be in love with the original design of your vinyl or plastic deck (or whatever) since it could be around for a long, long time.

Some plastic lumber, particularly the finished products like deck railings, come pre-colored — impregnated with a certain color throughout. However, plastic lumber isn’t porous, so unfortunately it can’t be reliably painted or stained, which can dramatically highlight real wood.

Most plastic lumber products can be slightly slippery when wet, even though a wood-grain pattern is sometimes molded into the surface. So think hard before using it near a pool, spa or any other surface where water might be present. Real wood, on the other hand, tends to soak up excess water, dries out faster and is usually cooler if you’re barefoot.

Structurally, plastic lumber is not as strong as real wood. That means that the supporting parts of the project (beams, joists, etc.) will need to be spaced differently. To achieve the same strength, you may need a quarter more plastic lumber than wood lumber. Currently, most building codes do not have specific standards for plastic lumber, although good designers will "overbuild" anyway.

If designed or built incorrectly, a plastic deck or fence may sag, especially in heat and sunlight. And since all plastics, by their nature, weaken with exposure to heat, a deck may get its weakest just at the time it gets the most use — the summer.

Material cost can vary widely. Most plastic lumber costs at least twice as much as chemically treated wood, but the cost gets a little lower every day. Some day in the future, the costs may be equal. Though the initial cost is higher, consider the fact that it won’t need to be replaced for a long time, and it may never have to be painted or waterproofed.

The labor cost is typically higher with plastic lumber. Most carpenters and contractors aren’t used to working with plastic lumber and lack certain tools, so they will charge accordingly. When this cost also gets lower, you may be able to make a choice using other guidelines.

My advice — since every project has different requirements, and every homeowner has a different budget and different level of expertise — is to figure it both ways. Only then can you decide the best way to go.

Owen Yost is an area landscape architect specializing in designing low-maintenance landscapes while incorporating native plants with hardscape. He is a member of the American Society of Landscape Architects, Keep Denton Beautiful and the Native Plant Society of Texas. His Denton office is at 4516 Coyote Point; call 940-382-2099 or 940-383-9655 or e-mail him at Yost87@charter.net