The question: When we had our deck built, we were told it would last forever. But each year a few more boards crack or rot and they’re expensive to replace. I suspect it’s not real mahogany. What do you think? Please don’t tell me to treat it. The whole idea was that this expensive hardwood would be maintenance-free, and besides, I’m all about that weathered look.

 

No matter what you’ve been told, mahogany is not forever. It will crack and dry over time if you leave it be. Even pressure-treated wood gets splintery if you don’t protect it.

I feel strongly that people should clean and treat their decks every two years. Yes, taking care of your deck will make it look new, and I know that won’t sway you if you like the wood to gray out. But it drives me crazy that people don’t see the environmental cost of ignoring and replacing the tropical hardwoods we use so often here on the Outer Cape.

I like the brushed-on oil-based treatments best. Think of it like waxing your car so the water beads up on the surface. The oil-based products wear slowly and won’t chip off unevenly the way water-based treatments can. And if you’re committed to the grayed-out look you can add a little gray tint.

You don’t want to put oil on top of mold, though. First you need to clean the wood well. Bleach-based cleaners used to be the only option, and that’s not exactly environmentally friendly. I’ve seen a lot of dead plants around the edges of decking thanks to bleach solutions. But now good hardware stores stock eco-safe peroxide-based options. They’re pretty easy to use. Or I call on Street Appeal in Harwich for this step.

I’m not for power-washing, unless you’ve got a serious buildup of mold on your decking. A good scrubbing is easier on the wood’s surface.

This kind of maintenance is the only way to make a wood deck last and I think it’s the responsible way to go. Look for a few clear days ahead and get it done this fall, or do your homework now and plan it first thing next spring.

This week’s Dovetail Joint question is answered by Todd Schwebel, a licensed contractor who lives in Truro and has been building and repairing houses — everything but roofing — here for 30 years.