Leave it to a chemist specializing in immune deficiency disorders to devise a pressure-treated wood that’s rot-proof, bug-proof, and so clean you could eat off of it. Its maker says it’s even safe enough to put in your mouth. But we’re not sure why you’d want to do that.
What you should do with it is build a deck, raise a garden bed, and erect that tree house you promised the kids. And sleep well knowing the wood won’t leach toxins or corrode the metal fasteners that hold all those weekend projects together.
The new lumber is called TimberSil, and it’s an alternative to wood preserved with potentially hazardous heavy metals like arsenic, chromium, and copper. Instead, TimberSil is infused with sodium silicate, a melted mix of sand and soda ash. The latter is a common ingredient in washing detergent. Once treated, the wood is baked in giant kilns to permanently encase its fibers with a flexible layer of innocuous glass. (Note that the amount of silicates used in the treatment process is too small to produce harmful dust when sawing, says TimberSil vice president Ron Hobbs. But standard respiratory and eye safety wear is recommended, as when working with untreated lumber.)
How it compares to other nontoxic options: Before TimberSil, borates were among the leading nontoxic wood-preservation alternatives. As This Old House Magazine detailed, borate treatment is toxic to rot organisms and wood-eating insects like termites but less harmful to humans than table salt. However, borates are water soluble, meaning they can leach out of wood that’s repeatedly drenched or in contact with the ground. TimberSil’s glass-encasing process aims to solve that durability limitation, making it suitable for outdoor applications like decks and garden beds without the risk of the preservative washing away.
Pro Tip: Tom Silva, general contractor for This Old House, has long advocated for pressure-treated wood in structural applications near the ground. “For sills and posts, it’s a necessary evil,” he says. “You feel a lot better being in a building or standing on a deck that is not rotting beneath you.” He recommends pressure-treated wood for all structural parts near the ground, including porch posts and posts in crawl spaces. Nontoxic alternatives like TimberSil offer the same peace of mind without the chemical concerns.
TimberSil arrives on the racks dry and ready to paint or stain. It offers more stability than other treated woods, which shrink as they dry, leading to cracks, splitting, and checks. And unlike its green-tinged counterparts, TimberSil retains its natural color.
TimberSil’s glass-infusion process also means it won’t leach toxins or corrode the metal fasteners that hold your projects together — a common problem with conventional pressure-treated lumber preserved with heavy metals like arsenic, chromium, and copper. That makes it an ideal choice for decks, raised garden beds, and children’s play structures where direct contact is a concern.
Because it’s essentially sealed in glass, TimberSil won’t break down in wet or moist conditions. “We’ve pulled the stuff out of the ground after more than a year and it comes out without so much as a nick,” says Hobbs. “After washing it off, it looks brand new.”
