The Deck Handbook: Part 3
Exotic and Imported Deck Woods
In the ever-widening quest for wood that looks good, is structurally adaptable and resists rot and decay, imported hardwoods have become significant niche players. The most common are Ipe (pronounced "ee-PAY") and the old standby mahogany. Others include Teak, Cumaru, and Jarrah.
The advantages of these materials are their relative durability and longevity. They resist the usual ills that befall decking woods — fading, rot, discoloration, and deterioration — better than almost any domestic wood except cypress. The disadvantage is their relatively high initial cost. Some of these products cost ten times more than treated pine.
Ipe decks are most commonly found on the coasts. It is the deck wood of choice where price is not an object. It has deep, rich color tones that make it unique as a deck wood. It is virtually maintenance free and requires no coating or treatments to maintain its strength or structural integrity. A clear oil finish can be applied to maintain the natural color if desired. Otherwise, the color will fade over time to a silver gray.
Imported from South America, Ipe wood (also know as Cambara Decking, Brazilian Walnut, Greenheart, Jatoba, Purpleheart, Massaranduba, and Ironwood) is very hard (3680 Janka) extremely resistant to decay, insects, damage from ice, salt, abrasion, splintering, chemicals and fire. The superior strength, density, hardness, stability, and durability of Ipe hardwood make it one of the very best materials for an outdoor deck. And one of the most expensive. It is 5 to 7 times more costly than a treated pine deck.
Much of the Ipe imported into the U.S. is illegally harvested. Any Ipe you buy should be certified by The Forest Stewardship Council as plantation-grown and sustainable.
Mahogany is an old standby — possibly the original premium deck material.
Used extensively in the 1930s and '40s as deck and hull material for powerboats, mahogany's resistance to decay and durability in an exposed environment are well known. Mahogany, however, is not really a species of wood as much as it is an umbrella term covering a variety of woods with similar characteristics.
There are many different species and subspecies of mahogany, and some woods called mahogany are not true mahogany at all. Colors can range from white and yellow to light and dark red. True American mahogany, which comes from the West Indies, Mexico, and Central and South America, is dimensionally stable and decay resistant, with a beautiful red color that made it the staple of Chris-Craft wood powerboats a few decades ago. You are probably most familiar with this wood in fine furniture.
Philippine mahogany (Luan or Meranti), comes in all colors and even has a dark red variety that looks like teak. Luan has a wide range of decay resistance and only some varieties are suitable for decks. Its most common use is in inexpensive hollow-core interior flat doors. Luan must be maintained with water repellent to protect it and keep its dimensional stability. It is not as durable or dimensionally stable as real American mahogany. True mahogany lasts, if well maintained, up to 30-years. Luan somewhat less.
Teak (Tectona grandis) is one of the best deck woods. It is hard enough to resist dents and mars (1000 Janka), but not too hard to be worked with fair ease — although it does tend to eat up saw blades due to its high silica content. It is another of those woods that started life as a maritime product. It is still commonly used as a material for luxury ship decks and upscale outdoor and patio furnishings.
Teak's use in boatbuilding dates back over 150 years. Teak is naturally resistant to rot, fungi and mildew and has a relatively low shrinkage ratio, which makes it excellent for applications where it undergoes periodic changes in moisture. As a deck, it requires little maintenance. Over time it will weather to a soft gray. Because its growth rings wear at different rates (softer "summer" growth tends to wear first), it forms a naturally non-slip surface. Sanding is not recommended nor is the use of most modern cleaning compounds, which can remove the natural teak oil in the material and actually shorten the deck's lifespan. Marine experts typically use specially formulated teak cleaners or just natural seawater to clean the deck. The salt in the water helps the wood retain moisture.
But, old growth teak is getting harder to find and more expensive as the planet's tropical forests are depleted. Most teak now originates from plantations where it is grown as a crop. Indonesia is the world's largest supplier of plantation teak, followed by India. The Forest Stewardship Council certifies teak as sustainably grown and harvested. Absent the Foundation's seal, teak should not be purchased. Even plantation teak is very expensive — probably the most expensive natural decking material. In many applications, it is being replaced by synthetic teak or alternative materials such as purpleheart (Peltogyne paniculata), iroko or African Teak (Chlorophora excelsa), and angelique (Dicorynia guianensis).
Cumaru (Dipteryx odorata) is an exotic hardwood species native to South America. It is also known as Brazilian Teak and Southern Chestnut and is very similar to teak in appearance and durability.
It is extremely dense and rich in color depth. Cumaru has a yellow-brown color that varies from a light yellow to mahogany red. It will darken slightly with exposure to light over a few months. At 3540 Janka, it is about five times harder than pine, cedar or redwood and is generally considered one of the most durable of deck hardwoods. Its life expectancy in a deck is about 25 years, but survival for as long as 50 years has been reported in semi-tropical areas.
Sealing is optional but will extend the life of the deck. The wood naturally weathers to a silver-gray much the same color as weathered Eastern Red Cedar. It can be stained and fading can be halted at any time with a UV resistant sealer such as Penofin.
Cumaru wood is incredibly fire resistant, having a Class A rating (the same as steel and concrete).
Harvested from managed forest projects, it is considered a renewable and sustainable "Green" material. Denser and harder to work that the softwoods, it is considerably more expensive to buy and slightly more expensive to install.
Jarrah or Jarrahwood is the common name of two entirely different wood species. The first, (Eucalyptus Marginata) is an Australian import. Widely used in that country for decks and outbuildings, it is a temperate climate cousin of the Eucalyptus and has the reddish hue typical of that family. It is fragrant when fresh, durable, resistant to rot and insect damage.
The second (Manilkara Bidentata) is a tropical wood found in the Caribbean, Central and northern South America. Slightly browner than the Australian native, it is commonly known as Jarrahwood, Massaranduba, and South Atlantic Jarrah. It is not related to the Australian Jarrah although it is very similar in appearance and working properties.
Both species are dense and hard. The Australian wood tests at 1910 Janka. The tropical variety at 3190 Janka. For comparison, Western Red Cedar, one of the softest woods used in decks is 350 Janka, and Ironwood (Lignum vitae), the hardest known wood (so hard it was once used for battleship main bearings), is 4500 Janka.
Both varieties are hard-wearing with a surface texture that finishes well to a deep rich color. Straight-grained Jarrah looks something like a red-stained Douglas fir and like some composite decking materials (which are, in fact, modeled on Jarrahwood).
With strand-woven bamboo flooring growing in popularity, particularly on the West Coast, bamboo decking could not be far behind. Essentially the same material but with an outdoor adhesive resin binder, bamboo decking is just becoming available through U. S. distributors.
The ultimate in sustainable, renewable materials, bamboo is not actually wood. It is grass stalks that have been pulverized into strips, boiled in boric acid (to remove sugars and repel insects), then woven together and finally bonded using some form of phenolic resin under 2000 tons of pressure into a plank. It depends on its bonding resin for much of its resistance to deterioration.
It is frequently advertised as a green material. It really is not very green. Natural bamboo is green, but, unfortunately, is useless for decking. For decking (or flooring) it must be broken down into to its constituent fibers and reconstituted. It is the elaborate processing it goes through — using lots of rather eco-unfriendly chemicals and an enormous amount of power — that make it a suitable decking material. In fact, bamboo decking is best viewed as an engineered composite material using bamboo fibers as a filler rather than natural decking like true wood. It may be "greenish", but it is not really green. It's what the environmental folk call "greenwashed", and despite its reputation for greenness, is actually less green that most domestic and many imported deck woods.
Bamboo is a wear resistant product with a hardness in the range of 2800 Janka — much harder than most natural deck materials. However the hardness of the material is very dependent on the specific chemicals used and the manufacturing process, so hardness may vary widely.
Some manufacturers are pretty confident of its durability, however, offering a lifetime warranty.
Wood-Plastic Composite Decks
When composite decking first hit the market around 30 years ago; it was trumpeted as the best thing to happen to deck building since decking screws replaced nails. Company advertising promised a new era of nearly indestructible, maintenance free decks that would last your lifetime. Turns out, it just wasn't true. . . . (Continues)