Going Green with a Black Locust Deck
So began an interesting project. Laura White and her husband Jamie were committed to building an environmentally-friendly deck, one free of chemical treatment. The original deck site was situated partly over their well, so they were concerned about possible contamination of their water by the wood treatment leachate. They consulted an EPA website and decided that a non-treated decking product would be their best choice.
Laura googled "green decking" and found information about Ipe ("ee-pay") and found that the properties of Ipe were well suited for decking. However, the price of Ipe , and the the fact that it has to be harvested in tropical locations and then shipped around the world, bothered the Whites, and they continued to look for other options.
They next considered wood-plastic composite decking but the Whites preferred the natural look and feel of solid wood. That's when they heard of a local project, a nature walk made from black locust lumber at the Shaver's Creek Environmental Center in the Stone Valley Recreation Center. They liked what they saw, and decided to pursue the dream of building their deck from black locust.
What their research turned up convinced them that black locust was the deck for them. Black locust has been used for centuries as fence posts and rails , because of its weather-resistant properties. Tales of 50-year old black locust fenceposts are common. Its durability has been recognized and researched for many decades. But beyond its durability, black locust has many environmental benefits. It is a preferred tree for honey bees, and grows nitrogen-fixing bacteria on its root system. It is an pioneer species that grows well on poor and rocky soils, so it often plays a beneficial role in land reclamation and soil stabilization projects. And especially appealing to the Whites, it is a local species to much of the Eastern United States, milled at many small, local hardwood sawmills. "We just felt that natural, local products are really 'greener' than many so-called green products marketed today," said Laura.
"Laura, I received your inquiry on black locust. This is a link you could start with, a company in Shirleysburg.
If they don't have what you're looking for, they can probably put you on to someone who does. Good luck, great idea, like to see your deck when it done!"
Laura and Jamie contacted the local mill owner, and found that he had a sufficient inventory of black locust to build their deck, at roughly one-third the price of Ipe! They contacted their neighbor and local contractor, Frank Bencsik, and the project took shape. Frank had a few comments about the project; it was the first deck he had ever built from black locust. He was initially concerned that the lumber would go through saw blades like candy, but that didn't materialize. "I had to change blades a couple of times; when you hit a hard knot sparks would fly from the saw," he said. "But nothing as bad as I expected. The bigger problem was trying to organize the decking from random width/random length lumber...no two pieces were the same size. I had to do a lot of shaving to get everything to look good." In time, the deck was completed, but the Whites faced another decision.
"Now for one more question...What (if anything) is recommended as a treatment for black locust? I get the sense from the internet that the stuff is so naturally rot- and insect-resistant that people don't generally treat it at all, but I don't want to risk making a mistake and putting nothing on it when it really should have something put on. Does it need some sort of treatment to prevent splintering as it ages? to prevent carpenter bee damage? Thanks in advance for any advice you might have."
"Great to hear that your deck project is coming along, Laura. To the best of my knowledge, your deck shouldn't need any treatment, but you may want to maintain it with a high-quality clear water repellent to keep it looking nice. Ultraviolet rays from sunlight and cyclical wetting from rainfall dull all deck materials over time, some faster than others. Since you won't be painting your deck, and want to enjoy its natural beauty, the more water-resistance and UV protection you can maintain, the nicer (and more slowly) it will weather. Of course, the value of black locust is its durability, so you could just let it weather naturally and forget the treatments if you don't care for the trouble and expense of the maintenance. Just expect the natural "sheen" of the deck to fade a little more quickly without treatment. Splintering shouldn't be a problem, and I imagine carpenter bees will stay away...it tastes bad and it gets harder over time. They have a lot better places to make their nests. The key time to watch for them would be in the first year...the wood hardens quickly and after that time they would need carbide jaws to carve out their niches. So just make sure to keep any bees away next spring/summer, and you'll be OK after that.
Be sure to invite me down to see the finished product...can't wait to see it. I've never seen a black locust deck before. Is your carpenter grumbling about how hard the wood is?"
Eighteen months later...
Hi, Chuck! My apologies for taking so long to get back to you. I wanted to include photos with my reply, and I'm afraid it took me longer to deal with them than it should have. I've compressed the files a bit, but if they're still too cumbersome for your system to handle, please let me know and I'll compress them even further or mail them in a few separate chunks. (By the way, the benches shown in the photos are also made of black locust, from the scraps left over from the deck construction. Man, are those things ever heavy!)
We're thrilled with how the deck/ carport has turned out. The locust survived the carpenter bees just fine this past season. While a wooden shed 20 feet away was being decimated by a giant swarm of them, the deck was completely untouched. We didn't even see any trying to make an attempt at it.
Our weather-proofing job could have gone more smoothly and yielded better results. On the advice of a local paint store owner, we applied Wolman's F&P Finish and Preservative -- Natural, in an attempt to prevent UV-associated graying. It ended up being a little less "Natural" than we'd anticipated, changing the color of the wood from honey to a more reddish tone -- still nice, but not quite what we'd expected. Our main problem arose not from the product itself, however, but from the freak 10-minute rain shower that came out of nowhere just a few hours into the 24-48 hour drying time. What a mess! We had a nasty slurry of partially cured finish and water that my husband finally ended up removing/ spreading around with paint rollers and old T-shirts. Needless to say, we had to recoat it, but the weather didn't permit this for quite some time. So the finish is now fairly uneven-looking. (To save time, my husband only recoated the decking and the bottom few inches of the sides, which didn't help the evenness of the appearance either.) Anyway, we love the deck itself are living with the imperfections of our finishing job.
A great job of "going green" by Pennsylvanians Jamie and Laura White. The amount of work they did in research made the project especially satisfying. Congratulations to them for highlighting for us a remarkable use of a remarkable wood.
"Hope this all helps!"
In response to this TechNote, Andy Winebrenner of York County, Pennsylvania sent me this interesting epilogue...
Chuck: I was highly interested in Laura White's Black Locust deck project. I, too, built a Black Locust deck in 1994, as part of my new home. Now, 15 years later, my Locust deck is still perfect! Initially, the golden color turned to a handsome brown, then darkened further over the years. I was in the paint business as part of my hardware store, and experimented with many different finishes, domestic and imported, and easily concluded that the Locust was far more durable than any conceivable finish. Today, my locust has darkened considerably (looks great to me!) but I've lightly sanded a small sample area down to the original golden hue, just to show all exactly what's truly under the darkened surface. I'm now 73, and it is very apparent that my beloved Locust deck will surely outlive me!
Beyond the locust deck you will probably be interested in this: I owned a Woodmizer sawmill prior to building, and sawed out all of my exposed beams, most of my flooring, all of my siding (board and batten white pine), the interior trim, and some handsome walnut for the kitchen cabinets, etc. But most importantly, I got Woodmizers shingle attachment, and sawed a Black Locust roof!! 4'', 6'' and 8'' random widths. My home is rather small (2400 sq.ft.) but required 10,250 shingles! Was quite a project to saw, and a real challenge to install. I obtained a stainless steel ringshank nail with special non-split tip that worked well, despite the hardness of the Locust. Now, 15 years later, the roof is just as perfect as the deck,and about the same color!! I have a great love and respect for all species of wood, (I used 13 different species in my home) but, needless to say, my absolute favorite is Black Locust!
Well, it looks like Black Locust is a wood well worth the extra effort, both from a "green" standpoint as well as for the satisfaction it provides its users. If interested, do a little research yourself, and if it looks like the right fit for you, give it a try!
Chuck Ray, Ph.D.
Penn State Wood Products Operations Specialist