To Deck or Not to Deck: Floors for Outdoor Rooms

posted in: Articles, Land Use, Publications | 1,122

This article was originally published in the New Life Journal.

Last month I sat down to write a column answering a question I get asked a lot: “What’s the best approach to building an environmentally conscious deck?” Instead, I ended up writing a preamble column introducing the concept of “outdoor rooms”.

The reason is that a deck is the floor of an outdoor room. Yes, even that rusty hibachi and those overturned plastic Wal-Mart chairs on that windswept tundra behind your house is a room, just not a very good one. Picture instead a living room with a door in the middle. On the tax map, half is “inside” the other “out”, but in reality it’s one big room that we migrate within based on the weather and our whim. Like the indoor part, the outdoor section has a floor, walls, and a roof. It’s a full-fledged, card-carrying room, part of the mansion of the outdoors. Versailles, the Acropolis, and a mighty redwood forest all with an internet connection and only 10 steps from the fridge.

For me, then, the first step in discussing decks is to place them in their context as the floor of an important room in your house. From that perspective here are my observations, opinions, and interpretive dance (sorry, for those of you not watching my webcam simulcast…you’ll have to check it out on YouTube.)

If you don’t design it, how can you know what to build?

Take a moment to imagine a room that you’d love to have. A bigger bathroom, a better kitchen, or a cozy study. I guarantee that your thoughts didn’t start with a rectangular floor of a defined dimension that you then imagined a room to fit around. Yet this is the process by which many outdoor rooms come into existence. A deck is built to an arbitrary dimension or simply to fit into a space and then…well, actually that’s it.

I say, forget the floor initially and decide what exactly the space is going to be used for. Is it public or private? Will you be cooking there? If so what? How much sun do you want? Do you want to encourage breezes or block the wind? How do you want to interact with rain? Is the outdoor room working with or embellishing an indoor room? Will this outdoor room interact with any other outdoor rooms? For example, a 2nd story deck automatically becomes the floor of an outdoor room below it, whether you want a room there or not. The difference between that space being a useless, dank eyesore and a useful, shady living room or outdoor workshop is simply the presence or absence of conscious design.

Size matters

One of the most basic tenets of green building is that “small is beautiful”. Smaller means fewer materials and less of whatever related pollution and other problems might be associated with their manufacture and installation. It also means more soil and vegetation left undisturbed, less maintenance, and, not insignificantly, less money expended. The same rationale is true for outdoor rooms, but the argument goes even further. Since the idea of an outdoor room is to be outdoors, the room itself should be only as big as it needs to be before transitioning to the “real” outdoors. An outdoor kitchen should transition smoothly to a kitchen garden, for example.

The best deck is no deck

Outdoor floors are exposed to a lot more moisture than indoor floors. Even a covered deck is going to get hit by rain or snow, let alone lots of water vapor from fluctuating humidity levels. Therefore, if your outdoor room is on the first floor, my advice is not to build a deck at all. Place your floor right on the ground by building a patio out of stone, slate, brick or some other variant. Yes, this will most likely cost more, but it will also last much longer and  won’t require the same maintenance. Patios can also be designed to slope gradually in ways that can eliminate steps and create smoother transitions between inside and out.

Local lumber

Obviously, there are situations in which decks will make more sense than patios. What should we build them out of? Until a few years ago, the common wisdom was to use wood that was saturated under pressure with a solution containing chromium, copper, and arsenic. For some reason, it took a while to determine that the known poison arsenic is still a poison when injected into wood, but eventually arsenic was taken out of the mix. Now, the pressure treating solution of choice seems to be copper oxide and “a quaternary ammonium compound”. Call me a Nervous Nellie, but I’m not comforted by this.

Enter locust tree, stage right. Locust is an incredibly dense wood that is naturally resistant to water penetration and insects. It grows straight and fast and is fairly abundant in our region, sometimes even considered a “weed tree” because it grows in damaged soils and is somewhat scraggly. Locust is a great material to use for both the framing and flooring of decks. The downside is that locust isn’t a huge tree and can be rough on saw blades, two traits that don’t put it on top of the favorites list for saw mills. (You can forget about ever finding it at Home Depot.) That means you may have to look around a bit to find some.  However, I’m sure that the more we ask for it, the more our local mills will want to carry it. One caveat: like any wood species, locust has its unique characteristics. Make sure that whoever is building your deck knows about locust or does some research on how to work with it.

Composite materials

There are a variety of “composite decking” materials presently being manufactured. Most contain recycled wood dust and either polyethylene or polypropylene plastic. Polyethylene is what grocery bags and milk jugs are made of and at least one manufacturer uses only recycled plastic from these sources. Some of these products contain PVC, others have anti-microbial and anti-fungal agents. To my ear, that translates to “against carbon based life forms”, a group that includes humans, so I tend to steer away from products proudly proclaiming that trait.

Composites won’t rot like wood and most have a gritty texture that gives them good foot traction. I don’t know of any of these products that have the structural strength to be used as deck framing. We’ve had good luck with some composites, so I think that locust framing with high recycled content composite decking without anti-anythings is a good combination for building a deck.

Oops, the long-winded blowhard alarm just went off. I’ve gone over my column word count allotment once again. One last comment: No matter what material you use, make sure that your outdoor floor slopes gently away from the house, so that water will too.

Until next month, remember it’s all good…except for the bad stuff.

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