Materials for the Great Outdoors
Whenever we start thinking about an outdoor project, from decks to furniture, our thoughts tend to turn to the traditional lumber choices of cedar and pressure-treated lumber. The truth is that there are many alternatives to these choices that can not only offer you more flexibility in your outdoor designs, but also can boost the quality and longevity of your projects. In this article we are going to take a look at some of the traditional wood and “wood-like” choices, as well as a few you may not have considered before. I’ve stuck with materials that can be worked with regular woodworking tools, but in your project planning you should also think about some other alternatives that work great outdoors such as concrete, stone, glass and tiles.
Along with cedar, pressure treated lumber is a very common option for outdoor usage. It does have one large advantage over cedar though; it’s generally much cheaper.
White oak has been used outdoors for centuries. It doesn’t rot easily, but does have a tendency to darken quite a bit when moisture reacts with it. Keeping it finished properly goes a long way to counteracting that. (Photo by A&M Wood Specialty)
Great Outdoor Accents
Though they can be pricey, mahogany (left), purpleheart (centre) and jatoba (right) stand up to the elements well. Along with a few other woods their bold colour make for wonderful accents.
Like its solid wood cousin, pressure treated plywood is great for areas that might see some moisture, but aren’t visible. It comes in a number of thicknesses.
This piece of medium density overlay consists of one piece of 7-ply plywood sandwiched between two very thin layers of waterproof MDF. Some manufacturers produce MDO with MDF face and back layers of different thickness.
Azek is available in many different trim options, so you can match the trim in your home to your deck. It will last for years without any maintenance whatsoever. (Photo by Azek)
Composites are made partially from wood and partially from a synthetic product. There are many companies that produce composite boards, and all are slightly different. (Photo by Trex Company)
Pressure-treated: This old standby, often the wood of choice for deck work, is softwood that has been chemically treated to resist rot and insect damage. While it is a functional and inexpensive choice for outdoor projects, many people are unaware that the pressure-treated lumber available today is much different than that of a decade ago and requires special treatment. Once treated with toxic chemicals such as arsenic, environmental concerns have resulted in a new breed of copper treated lumber. While less toxic than its predecessors, it is extremely hard on some metal fasteners, with stainless steel being the fastener of choice for longevity. Also, you’ll want to ensure that no aluminum comes in contact with this new pressure treated lumber, as it corrodes extremely quickly. For flashing and hardware, stick with painted steel.
Red/white cedar: Probably the most popular choice for outdoor furniture. At one time this attractive and rot-resistant wood was used to build entire decks, but as costs escalated, most builders now choose a compromise for decks. At a cost two to three times that of pressure-treated, it is quite often used in conjunction with its green-coloured cousin, being used only where it’s visible, such as for decking and railings over pressure-treated framing. Cedar is strong enough to build most outdoor furniture, and if left unfinished fades to a classic silver-gray colour.
The hard alternatives: Just because it’s used outdoors doesn’t mean it has to be softwood. White oak, for example, has a long history of outdoor use … in fact, it was often chosen to build the wooden sailing ships and piers of old. Patio furniture in quarter-sawn white oak would look fantastic and last for years. Mission-style anyone?
Ipe is a relative newcomer to the scene that is quickly gaining popularity with woodworkers and carpenters alike. Also referred to as “Brazilian walnut”, this attractive teak lookalike is heavy, dense, strong, and virtually indestructible (it even carries a US fire rating equal to concrete!). Mainly imported for decking, it makes an excellent mid-price choice for outdoor furniture projects as well. Be forewarned though, it will require pre-drilling for any fasteners and will have a tendency to dull your tools. On the upside, because it’s naturally oily and very hard, it requires no added finishes to protect it, and a light sanding and a rinse every few years is the only maintenance required to keep it looking great.
Exotics and accents: There are other hardwoods that work great outdoors, but due to cost are often used for smaller projects or as an accent on larger ones. These woods include purple heart, most mahogany, teak, blood wood, and jatoba (Brazilian cherry). Picking one of these exotics to add to your outdoor projects can add visual flair and really make your project stand out.
Believe it or not, there are sheet goods specifically made for use in outdoor projects. While these may not be commonly found at the big box stores, most lumber yards will either stock them or be able to order them in for you.
Pressure-treated plywood: This is standard spruce plywood that has received the same chemical treatment as pressure-treated lumber to help it last as long as possible outdoors. Available in 4×8 sheets and in common thicknesses, it’s an ideal choice for outdoor construction, especially for applications where it won’t be seen, such as shed floors.
Waterproof MDF: Yup, the sheet material that we love to hate is available in a waterproof version. It looks and works very similarly to regular MDF, but uses waterproof resins to allow it to be used in the great outdoors.
MDO: Medium Density Overlay is a “sandwich” consisting of two thin sheets of waterproof MDF wrapped around a core of plywood. Originally developed for making outdoor signs, it works great for any application where you will be painting the final project.
Azek/PVC Sheeting. This stuff is the final word on longevity for any outdoor project. Available in thicknesses from 3/8″ to 1″ and in sizes up to 4′ x 20′. The material works very much like wood and can be routed or cut with standard woodworking tools. Like wood, it can be glued, screwed or nailed into place. And because it is 100 percent plastic, there is no wood fibre to rot, fade or discolour.
I’ve noticed that regardless of what the decking is made from, if it isn’t solid wood many people call it “composite decking”. It’s important to understand, however, that composite is a very specific type of decking that is composed of plastics and wood fibre or sawdust, hence the term “composite”. There are pure plastic and PVC selections available as well, and the non-composites tend to be my choice for most projects, although in the past I have installed pretty much every type of manufactured decking.
Off the top of my head there’s polyethylene, polypropylene, PVC, hollow, solid, wrapped, etc., and to get into the pros and cons of each type would take an entire article in itself, so here we’ll just look at how you can use it.
Obviously decks come to mind, but I’ve found it generally works very well for pretty much any woodworking project where you would normally use 5/4 cedar or PT decking. I’ve used it for docks, utility trailer sides and decking, table tops, rural trash can boxes and even Muskoka chairs and benches. The uses are pretty much endless, and there’s the added benefit of having your completed projects look as good in five years as they did the day you built them, and with virtually no maintenance.