Renovation & Design

Outdoor wood projects demand careful thought, research

Postmedia/Different types of wood for exterior projects require different levels of maintenance, as well as specialized fasteners, including vinyl-coated, ceramic-coated, galvanized, zinc-dipped and/or stainless steel.

Now that it's summer many homeowners have outdoor projects on their minds. The most popular are decks and fences, and the most popular material for these types of projects is wood, by a long shot.

When it comes to outdoor wood projects and materials, the three big contenders are pressure-treated or PT wood, cedar and composite. They each have their pros and cons, but what it usually comes down to is what do you have more of? Time or money?


Pressure-Treated (PT) Wood

Pressure-treated lumber is wood that's been treated with chemicals to make it resistant to rot and insects. Between composite and cedar, PT wood costs the least, which is probably why it's so popular. The main thing to keep in mind is that you can't use it indoors -- it's strictly an exterior product -- you can't burn it because of the chemicals in it, and you need special nails and screws.

Back in the day, arsenic was used to treat PT wood and make it weather-resistant, but that was replaced with copper. The problem is that when PT wood gets wet the copper in it will start to corrode metal fasteners, including nails, screws and deck hangers.

You also need to be careful if your project requires flashing. Most flashing is aluminum, and exposed aluminum will corrode if it comes into contact with moisture, especially wet PT wood. Regular galvanized nails and screws won't hold up for long either. You'll start to notice staining around the screws and hangers, but eventually, they'll corrode completely and could lead to structural failure.

Stainless steel fasteners will not corrode but they're expensive, which doesn't make them practical -- especially if you're trying to save some money by going with PT lumber. Your best bet is to use vinyl-coated "green" wood/deck screws. These are resistant to the chemicals in PT wood and some even have lifetime guarantees.

To keep PT wood looking good it needs regular maintenance -- sanding, sealing, painting or staining. It's less maintenance if you stain it rather than paint it, but if you want longevity with little to no maintenance consider another material.



Cedar looks and smells great, and it's a popular building material for exterior projects for a few reasons:

One: It won't warp when exposed to moisture, which is good for the outdoors.

Two: It's naturally resistant to rot and insect damage, so no dangerous, corrosive chemicals or off gassing.

Three: It requires less maintenance than other types of wood, like pine or spruce -- even PT wood. All you have to do is clean it at least once a year with a mild detergent and water. Just don't use a pressure washer. Cedar is soft and a pressure washer can damage it.

Four: You also don't need to treat it with preservatives, unless it comes into direct contact with the ground, which it shouldn't if your structure is properly built -- you never want wood touching soil.

Five: It's resistant to temperature-related stresses, which makes it good for outdoor projects where temperature changes and splitting are common.

But cedar has one big drawback: It's expensive -- more expensive than PT wood, no question. If you like the look of cedar but you can't take the cost, one way to save some money is to build your structure and support out of PT wood and use cedar for railings and surface planks. This will give you the look and smell of cedar, and some added strength and support.

Just remember: Use stainless steel, zinc-dipped or ceramic-coated "brown" wood/deck screws when working with cedar, and if you decide to stain it you will have to maintain it regularly. Cedar doesn't need to be stained -- it weathers to a grey-looking colour, which some people like. But if you want to keep it looking like new it will take some elbow grease every two-to-three years.


I didn't like composite wood when it first came out but it's improved over the years. Composite wood can be made from a combination of different ingredients, like polyethylene or polypropylene mixed with glass, wood fibre, wood flour, as well as other wood and recycled products.

It can be textured to look like real wood, and different types are resistant to UV, fading, stains, insects, splitting and/or warping. But it will cost you -- up to five times more than PT wood.

No matter what type of material you decide to go with, do your research, hire the right pro and know exactly what it will take to make it last. For example, if you're building a deck, most contractors will tell you the joists need to be 41 cm on centre, but 30 cm is better to prevent warping and dipping, especially when it comes to composite wood.


--Postmedia Network Inc. 2014


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