Wood Fences

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Best and most elegant woods for fencing come from evergreen softwood containing resins that naturally repel molds, termites and other boring insects. The best known is California redwood; heartwood of this tree will last for 25 years or more without treatment.

But, being in demand for outdoor furniture, siding, decks and railings on upscale homes, redwood is expensive. Also, this wood doesn't tend to last as long in regions outside of California. Not quite as costly, but not cheap—and often hard to locate because it is sold primarily to outdoor furniture and fencing manufacturers—is Western white cedar (most of it from Canada).

Aromatic red cedar, cherry and a few other resinous furniture woods would make good fences, but are better used in cedar chests and dining-room tables. Red cedar and cherry are extensively used on both the East and Pacific coast. Wood that's good for naturally long-lived fence posts—and that you might find in your own woods or at a local rough cut sawmill—include black locust, the mid-western nuisance tree (with its huge, messy but inedible fruit), the Osage orange, catalpa, red mulberry and sassafras.

Old-timers prolonged the in-ground lives of fence posts by charring the ends in an open-pit fire. Then they'd sprinkle rock salt into the hole as soil was being tamped around the posts. The char and salt lasted and kept bugs honest for a good while. You can do the same with your homegrown posts—just don't add salt anywhere near the garden or young fruit trees.

But don't plan to dig a pit and soak your own posts in chemical preservatives. Once common "Penta" and creosote pose environmental and human-health hazards, and the Environmental Protection Agency has restricted their use to professionals. Rails and infill boards can be cut from large, straight specimens of these rot-resistant tree species as well as hemlock, white pine and the oaks. But the latter woods will need periodic treatment against airborne molds and should be stained lest they discolor.

Do not use common hardwoods or conventional dimension construction lumber for fence. When new to the country, I built a big, wire-roofed flying pen for chickens from poultry netting strung on a frame of sturdy sugar maple saplings. Within two seasons, the posts rotted and snapped off at ground level. Pine and spruce lumber will build into sturdy homes, but—left outside—will discolor to an ugly brown before rotting, unless stained and treated periodically with fungicide. But, with a stain, spruce will last as long as 12 to 15 years. The most economical fence stock you'll find is pressure-treated (PT) lumber—those bilious, green-dyed beams, round posts and flat boards you find stacked outside most lumber yards. Made from construction-grade soft woods such as Southern yellow pine or Douglas fir, PT is saturated through with CCA, a copper-arsenic compound that is a mild, but long-lasting poison and repellent to bugs and molds. It should be noted that environmental purists worry that CCA—which slowly leaches out of the wood over the years—will harm nearby plants.

While the risk of any significant environmental damage is minute, don't ingest edible plants grown close to your fence (better safe than sorry). Also, you should always wear a respirator when cutting PT wood. For the longest-life, get posts that haven't just been dipped in green stuff, but are certified to have been pressure-treated to 40 pounds per cubic foot.

While many fence companies will guarantee 40 to 50 years for PT fence life, it's probably closer to about 20 years—still a long time. It doesn't matter if the wood is still dripping wet; indeed, wood is fresh-cut and true when it goes into the pressure tank and you are better off nailing it up wet and straight than waiting for it to dry and warp or twist. Do beware of cut-rate PT lumber from roadside wood yards, however. Small, local processors have been know to skimp on treatment. Buy name brands or take the word of a well-established lumber yard.

Expect to pay approximately $6 to $7 for an 8', 4" square PT post (due to skyrocketing prices of this past spring), and $12 for a 6 x 6 x 8. A 2 x 4 x 8 length of PT rail stock will cost a dollar and change, a 2 x 6 x 8 perhaps twice that. When choosing lumber, don't be afraid to pick through the piles, insisting that a new bundle be unstrapped if you can't find enough good wood.

Look down the long, narrow edge of a board to detect warps and twists. Reject any boards with large cracks, loose knots or black rot holes in them. PT wood will bleach to a lovely ashgray in time, or—after drying for a season—will accept any stain or paint. You will not find 1" nominal (actual measure 3/4") PT to build into infill boards, but many yards stock "5/4" (actual thickness 1") boards in varying widths. Square or round-edge ("eased") deck flooring in a 6" width makes a good board fence—especially if you find a large supply of picked-over long boards that you might get at a discount, then trim out the bad sections.

Or, you can use 3" or 4" pickets pre-cut from cedar, redwood or no-name imported wood that comes as is or pre-primed in white. Posts must be PT or naturally rot-resistant wood. PT wood is also best for rails and infill, though any strong, sound wood will last if kept out of contact with the ground and if treated with sealer or mildew-proofer. But if you plan to paint your fence, you can scrounge rails and infill boards by looking in demolition dumps, around remodeling projects, and in building materials recycling outlets. Random widths and even thicknesses look fine when infilling a fully boarded or a "shadow" fence—where boards are spaced apart about half their widths on both sides of the rails, boards on one side covering spaces on the other. This design lets air flow through, but if high enough can offer an effective barrier for privacy.

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