Not All Decks Are Created Equal
Jul 31, 2016 10:59PM
By Matthew Schlueb
If you are anything like me, the summer season starts off with a list of projects to do around the house before summer's end. A list that grows, more often than shortens.
If this third month of summer enters with a deck project still in the planning stages, the following are a few things you might consider in selecting an exterior decking material:
There is no substitute for the romance and feel of a natural wood. Manmade composite decking options may be lower maintenance, but have a synthetic look and feel—no soul, in my opinion. If natural wood doesn't appeal enough to your sensitivities, unlike petroleum-based composite materials, wood is completely renewable when sustainably grown and harvested—even with a carbon footprint that sequesters rather than contributes to climate change.
As far as maintenance goes, if hosed down at the end of each season on a bright sunny or windy day so that it dries quickly, wood will last for years. If you don't like a naturally weathered, soft silvery grey appearance but prefer wood's virgin color tones, a water-resistant, UV-preservative stain applied every two or three years is all that is needed. Personally, I’ve found the satisfaction and relationship created by maintaining a deck over the years has been rewarding, the kind of thing gained by tending a garden.
If you are sold on a natural wood deck, it's important to understand that the material is in a state of continual change. So-called ‘rot’ is really a beautiful and necessary step in a tree's contribution toward the larger web of life on our planet. Decomposition returns and replenishes the soil with a lifetime of nutrients collected during the photosynthesis process. As sunlight and wind dry out fallen wood, it will expand and split, exposing entry points for water. This results in further swelling, supporting mold and fungi growth, which, along with insects, consume the fibers as a food source.
When a deck is in contact with ground soils or climbing vines and other vegetation, the process accelerates. Our tendency as the owner of a wood deck is to slow this natural process to appreciate its full beauty and integrity—but do not be under the illusion that this grand cycle can be altogether stopped. The slower woods—the ones taking their time in this cycle of life (i.e., those that have greatest ‘rot’ resistance)—are not surprisingly more costly in our capitalistic marketplace. Black locust, Mexican teak, south Florida ipe, California redwood and bald cypress top this list.
Other beneficial characteristics to look for in selecting wood are a tight grain, which makes the wood denser and heavier but stronger; the slower heartwood, which is usually darker than the sapwood; and quarter sawn (vs. flat sawn), making it less likely to warp or cup. If only flat sawn is available, be sure to lay the boards with the crown (bark side) up to prevent water ponding.
Black locust is the most local of all the wood species, found growing in our Midwestern temperate region. Ranging from a pale greenish yellow to darker brown in color, this wood darkens to a russet brown with age. Although grains are typically straight, this high density hardwood makes it difficult to nail or screw. However, this also makes it second only to hickory as the strongest and stiffest domestic timber, unsurpassed in stability. Best of all, it is one of the least threatened species with regards to deforestation, so with my clients, it is usually my first recommendation.
Mexican teak has high density and excellent stability but low availability, so it is best when needed in small quantities. Part of that low availability is a result of a slow growth technique on plantations to mimic the soil and precipitation characteristics of the old growth tropical forests in Southeastern Asia, which resulted in teak's legendary grain pattern and golden brown color. Its low availability and typically small pieces both contribute to it being one of the highest priced woods on the market.
South Florida ipe is a tropical hardwood that is extremely hard and very high density with excellent stability, but is also low availability. Its dark rich crimson color heats up to the touch in full sun. A smooth finish and tight grain results in no splinters but heavy boards that are difficult to cut and drill, which is why it is typically installed with hidden clips or biscuits. It does not take stains well, but accepts finish if weathered a couple months to leach out excess oils.
California redwood is a low-density softwood that easily damages from heavy foot traffic. Lightweight and stiff with good stability, it resists warping, checking and splitting. Its open-celled structure contains little or no pitch or resins, absorbing and retaining stains easily. However, it is the natural beauty of the light to rich dark red color that adds to its popularity and has resulted in its depletion down to only 1 percent of the old growth stands remaining in the Pacific Northwest.
Bald cypress is a softwood conifer native to the southeastern United States, thriving in flood lands and swamps. It is light yellowish brown in color, sometimes with pockets of darker wood resulting from wetland fungi attacks. A medium density wood with good stability, it is widely available and therefore not a threatened species for extinction.
Western red cedar is a softwood with low density, good stability, but a tendency to splinter. It has a natural hardiness that changes its moisture content to closely match the atmosphere. Light brown to salmon pink in color, often with random streaks or bands of darker red brown areas, it is highly available but avoid old growth as it is in danger of extinction. It has a moderate resistance to decay, with a mixed resistance to insect attacks.
European larch is a softwood conifer that is widely available, harvested as construction lumber with good stability. Natural resins offer a moderate resistance to decay, but have a tendency to gum up saw blades. This wood ranges from yellow to a medium reddish-brown in color. Knots are common, but are usually small in size.
Southern yellow pine has the lowest natural resistance to decay, and when pressure treated, exceeds all other natural woods. Low density and high strength make it the strongest of all softwoods, although it is susceptible to splits, twists and shrinkage. These facts combined with wide availability and low cost make it the most popular wood sold. Naturally golden yellow in color, its heartwood does not accept preservatives and is therefore not decay-resistant, appearing tan or pink instead of the green color of treated sapwood. Because of the chemicals used to pressure treat it, always use gloves and a mask when handling and never burn it.
For more information on selecting the right wood for your summer projects, contact the Forest Stewardship Council (FSC), a nonprofit organization certifying lumber that is harvested in a legal and sustainable manner.
Matthew Schlueb is a registered architect and owner of SCHLUEBarchitecture. For questions or comments, contact Matthew at firstname.lastname@example.org. This article is part of an ongoing series addressing architectural issues for homeowners.