Home Improvement

Published on Thu, Mar 13, 2008 by Jack Kintner

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Home Improvement

By Jack Kintner

Decking materials vary in cost, suitability

Cedar is the traditional material for northwest decks. Easily worked and attractively colored, the wooden planks used for a deck surface cost well under half the next most suitable alternative, composites made from a combination of recycled plastic material and wood material, usually shavings of some kind.

The trees that this wood comes from, technically known as western red cedar, are northwest icons, and were used extensively by natives for millennia for everything from boats to clothes to artistic carvings to huge flat planks with which they built portable houses of impressive size.

Since they contain natural defenses against rot and insects, some tribes developed ways of extracting a log big enough to make a canoe out of an old-growth giant without sacrificing the tree itself.

Cedar’s easy workability is also why people are looking elsewhere for suitable materials, because it dents and chips so easily. For piers or other waterfront construction fir is more commonly used because of its durability.

Both woods need regular maintenance and sealing to keep from deteriorating, which begins to make the case for composite decking material, especially for the walking surfaces, the part you see when the work is finished.

Even though the initial cost is higher, the cedar deck will eventually catch up with the composite deck in cost because of the dramatic difference in the cost of maintenance over time.


Some brands of composite material for use as decking surfaces are made by combining a blend of plastic and waste wood fibers. Others are just plastic.
The ‘boards’ cannot splinter and don’t need to be stained or painted. Aside from being more expensive, though, they’re also heavier than wood and must be pressure washed or scrubbed annually to prevent mildew.

Another way that composite material costs more initially is that since it’s not as stiff as wood it needs more support.

If you’re rebuilding an old deck you can expect to add stringers to the support system if replacing wood with composite decking as the composite boards are usually not designed to span more than 10 to 12 inches.

Some brands do furnish beams made of composite materials, and others design their boards out of plastic that is stiffer and able to span greater distances because of their design.

The problem with some of the plastics and composites is that they expand and contract much more with temperature than wood, which means that the attachment systems are crucial to getting a satisfactory result. Otherwise they’ll
tend to work loose and begin squeaking when walked on.

Greener building

Another reason to use composites is that one is reusing materials that have already been harvested once from their natural sources, in this case oil for the plastic and trees for the wood chips. Since the material is impervious to water and there are no weather worries, aside from making sure the material is firmly attached to its support system, one can get quite creative with deck designs, incorporating such things as integral planters, solar lighting, hot tubs and curving, multi-layer surfaces.

Wood still has a place in deck design, of course, in both the underlying support structure and especially as a visual or structural highlight. A curving front edge, meanwhile, can be accentuated with a curved railing.

A view can be preserved by making a deck railing out of panels of welded wire, or hog fencing, that’s powder coated to prevent rust. Framing each one with wood tends to help them blend in better with the support structure. Or wood can be used for trellises that provide summer shade, especially when combined with climbing plants such as grape vines or Wisteria.

There comes a time in the fall when your outside deck living will have to come to an end because of weather. Jerry Thramer at Innovations for Quality Living in Bellingham said that there are several new kinds of outdoor zero clearance wood fireplaces that can extend the time that one can comfortably use an outside living space. Zero clearance means that the fireplaces can be framed or somehow embedded in the deck design. This must be done, because of the weight, with wood, but you can use a composite deck as a support system if it’s engineered correctly.

If your home is not served with gas you can now get small liquefied propane (LP) gas tanks of about 150 gallons that sit on their own little concrete pad right next to the house – no need for a long trench to the far corner of your lot, in other words.

A 30,000 BTU fireplace, enough to do a reasonable sized outdoor area the size of a normal living room, say, burns just a gallon of LP gas every three hours at 95 percent efficiency.

That means two things: the fireplaces are so efficient there’s no chimney at all, and they’re very cheap to run. A normal 150 gallon tank will run a unit like this for 450 hours, about 18 days if burned non-stop, so it would easily last a season.
“People sometimes ask about putting them inside,” Thramer said, “which I don’t like because gas burning puts out a fair amount of moisture. You don’t want that inside your house, but outside it actually helps, because humidity helps spread the heat and makes you feel warmer.”

All the components on these new fireplaces are stainless steel so there are no problems with rust. Another application for stainless is a new kind of firepit that begins with a stainless steel donut that can be buried under non-flammable material to have flames emerge from rocks, glass or whatever your imagination can think of.

“Just leave a hole in your deck and put a fire ring in it and let your imagination run wild,” Thramer said, “like one we just finished installing that has volcanic rock around the ring to support it and then glass on top of that. It’s very striking.”

The stainless steel fire rings come in one to four foot diameter sizes and start at less than $100. “The gas company will deliver the tank, and we pipe from there to where your unit is. It’s a very effective touch that’s inexpensive to buy and operate,” Thramer said.