This Old House Magazine: Standing Tall

Columns can decorate a facade and play a supporting role

By Jefferson Kolle
From This Old House Magazine
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Columns have graced public buildings and private houses since ancient times. Rising up elegantly, decorative columns call attention to themselves. Sometimes columns are structural as well as ornamental, supporting a wall, a roof, or a building facade. The aesthetic effect can vary: A row of columns adds formality to a building, while a pair points out an entryway or key detail. Although the classical designs of ancient Greek and Roman columns are as popular today as ever, don't feel bound to build the expected. Different column shapes have evolved since the days of the Parthenon: Late-19th-century Shingle Style buildings featured stone or shingled columns, and the porches of Craftsman bungalows often rested on dramatically tapered, pyramidal wooden columns.

Today, premade columns come in many sizes, shapes, and styles. In addition to off-the-shelf designs, columns can be custom made for more exacting house restorations. At the This Old House TV project in Manchester, Massachusetts, general contractor Tom Silva replaced the fluted columns on the home's front portico with custom replicas made from weather-resistant heart redwood. "It was as close to the originals as we could get," he says. "But all wood, even redwood, is prone to rot eventually, so care has to be taken to repel moisture." To that end, the new, hollow wood columns were ventilated with air passages in the base and the capital, and the interiors were coated with waterproofing material for added protection (see "Venting a Column," below).

Columns today are often made of rot-resistant man-made materials instead of wood. For the porch at the back of the Manchester house, Tom Silva chose columns made of a weather-resistant polymer. "To the eye they're indistinguishable from real wood, and a lot stronger," he says. These polymer columns (made by Fypon) have a load-bearing galvanized steel pipe inside, so they're strong as well as decorative. An 8-inch-diameter column can support loads up to 12,000 pounds—roughly twice as much as a similar column made of wood.

Lightweight and purely decorative, columns made of expanded polystyrene foam can hide structural wood, steel, or concrete posts. Composite-stone columns, made from resins, fiberglass, and marble dust, are extremely weather resistant and need no interior ventilation. Aluminum columns with a baked-on enamel finish are available in load-bearing and nonbearing versions.

The price of adding columns to your home will depend on the size and material of the column, its load-bearing capacity, and the amount of detailing. A plain, eight-inch-diameter, eight-foot-long wooden column in pine, hemlock, or fir costs about $160. Double that price for one made of redwood or cedar. A comparable column in polymer is a relative bargain—$200 or so for a plain, round eight-footer. Installation will add to the price, but, then again, what else can give your house, porch, or entryway the splendor of a Greek temple?

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Venting a Column
Hollow wooden columns must be vented to prevent built-up moisture from condensing on the inside and rotting the wood. Proper ventilation requires an opening at both top and bottom, providing a chimney effect for the passage of air (see illustration, right). As a rule of thumb, to determine the amount of ventilation needed, divide the column's diameter (or width) in half and convert to square inches. For example, a 10-inch-diameter column needs five square inches of vent opening at the base and another five square inches at the capital. To keep insects and small critters at bay, the vents should be blocked with copper screening.
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For additional moisture protection, This Old House general contractor Tom Silva coated the inside of the hollow redwood columns that flank the front entryway at the TV show's Manchester house (right) with Geocel—a rubbery waterproofing material that expands and contracts along with the wood as the temperature fluctuates.