Classic Solutions for Column Repair
If you’ve got columns - interior or exterior - you’ve got a distinctive architectural feature well worth preserving. But, before you repair or replace them make sure you understand the finer nuances of their design, proportion, profile and materials.
Originating in ancient Greece and Rome, columns are architectural hallmarks of classical design. They are characteristic of Georgian, Federal, Greek Revival and Renaissance Revival style buildings, and they also appear variously interpreted on a range of 20th century houses. Columns are typically based on the five classical Orders descended from antiquity. The Greeks first developed the Doric, Ionic, Corinthian orders. The Romans later modified those three basic types and expanded the list to include the Tuscan and Composite Orders.
The Classical Orders
The Orders include the design of the column’s base, shaft and capital, and the entablature above it. The entablature is the ensemble of horizontal elements or the "beam" supported by the columns. These elements are called the cornice, frieze, and, the lowest horizontal member, the architrave. Proportion is key to a correctly detailed Order: the diameter of the column must be in proportion to its height and to every element of the entablature. Classical columns are broader at the base than at the capital. The column’s tapering - or entasis - begins one third of the way up the shaft. Too often, homeowners who are unable to find an appropriate replacement column will settle for an untapered, garden variety column that lacks the classic ratio of width to height, and the subtly important entasis characteristic.
The earliest written description of any of the Orders is in Vitruvius, a first century Roman architect, who describes the Ionic, Doric and Corinthian, with notes on the Tuscan. Fourteen hundred years after Vitruvius, the Florentine architect Alberti described the Orders by referring to Vitruvius’ writings and carefully observing the Roman ruins for himself. He added a fifth order-the Composite-which combines features of the Corinthian and the Ionic. A century later, Serlio, established the precise dimensions, profiles and proportions of the Orders in several books, which soon became the architectural bibles in Europe and England.
Exterior columns are integral to the porch/portico/veranda. If they are deteriorating, check your porch roofing and gutters to make sure they are not allowing rain water to collect around the column capitals or bases. Often water penetrates between the exterior wall and the structure of the porch. To prevent this, install metal flashing into the brick coursing or weatherboard of the exterior wall and fit it to the contours of the porch roof. A good flashing detail is essential to securing a watertight porch roof. Seek expert flashing advice if needed.
In addition to installing flashing, also, check beneath your porch framing for signs of rot or decay. Deteriorating porch joists or girders can cause the porch floor to sag or drop, which can lead to more serious fractures, cracks or occasionally outright porch collapse. Before treating the deterioration on your columns, consider how the effects of the same deterioration have affected the porch structure itself. Repairs should be focused first on the porch piers and floor framing system supporting the deck and columns above. It’s not unusual to find rotted porch decking and structural framing members in close proximity to the deteriorated columns. The choice of appropriate repair materials for the porch as a whole is also an important consideration. Repairs should be done in such a way that they blend inconspicuously with the surviving porch construction, and will weather in a similar way.
Wood vs. Fiberglass Columns
Many historically-sensitive, environmentally concerned homeowners are wary of synthetic columns. Fred Siewers III of Siewers Lumber and Millwork, www.siewers.com a 115 year-old company in Richmond, VA, sees advantages and disadvantages to both: "Wood is beautiful. It is the most humanly intimate of all material" he says. "Also, in the age of green building, it is a fully renewable natural resource. Wood will always have its place."
Siewers also notes the improved quality of many man-made wood substitutes, such as fiberglass and PVC. He thumps a fiberglass column with his fingers. "They even sound alike now. It’s hard to tell the difference." Many renovators choose man-made columns for the exterior and wood for the interior, Siewers says. "Fiberglass columns are rot proof, weather proof, insect proof, and highly durable. Commercial wood columns are available in stain grade (such as pine, walnut, oak and cherry) for interior use, or finger-jointed paint grade for exterior use. Cost is not a big factor, because most fiberglass columns are only slightly more expensive than wood columns of the same size."
However, architect Doug Harnsberger, who specializes in architecture for historic structures, argues in favor of authenticity: "For scrutinized historic house rehabilitation and restoration projects, such as those seeking state and federal historic tax credits, selecting an authentic wood replacement column may be required to satisfy the specific rehabilitation requirements of the program," he says.
Harnsberger points out that the Secretary of the Interior’s "Standards for Rehabilitation" that apply in such certified historic rehabilitations usually will insist that any deteriorated wood columns be replaced "in kind" with closely matched wood columns. Substituting a fiberglass column for a wood column will not be an acceptable alternative under such an "in-kind" replacement expectation. In general, if homeowners are uncertain of the making the correct selection, Old House Authority suggests they get the best technical advice in advance of doing the repair work from their State Preservation Office (www.ncshpo.org/stateinfolist). In order to be confident about selecting the most appropriate "in-kind" replacement materials as part of a certified historic rehabilitation project, it’s best to consult first with experts at the State Preservation Office. [Another source for wood columns is Chadsworth http://www.columns.com/]
Plaster or Rendered Columns
Restoring authentic plastered or "rendered" exterior columns requires the skilled hands of an experienced plasterer to be successful. While reconstructing an entire classical plastered column is achievable, it may be prohibitively expensive to undertake. "Making custom plaster molds of the ornate base and capital, and a precise, matching profiling of the column’s shaft are time consuming challenges for the plaster artisan," Harnsberger says. "Spot repairs to an aged plaster column or resurfacing the entire column shaft with a new white finish coat of plaster are less expensive procedures that many homeowners can afford." Should you find some deteriorated historic plaster columns on the front porch of your house, Old House Authority recommends you consult first with a skilled historic plasterer to provide an informed restoration recommendation.
Sizing a Column
Siewers recommends dividing the opening height (in inches) by the divisor (from the chart below) of the chosen Order. The result is the column diameter in correct proportion.
An example using an opening height of 96":
|Tuscan||7||96/7=13.7||14" x 8’|
|Doric||8||96/8=12||12" x 8’|
|Ionic||9||96/9=10.7||10" or 12" x 8’|
|Corinthian||10||96/10=9.6||10" x 8’|
|Composite||10||96/0=19.6||10" x 8’|
Columns are available in round or square shape. Round columns are fluted or plain. Square columns are available in a variety of styles, including plain or fluted, applied panel moulding, recessed panel, or the craftsman-style column. Siewers says that stock sizes typically range from 6" to 30," although they can be custom milled in nonstandard shapes and sizes.
The Bottom Line
Historic wood classical columns communicate a direct connection to the ancient building traditions of Greek and Rome. Their essential wooden characteristics are part of that classic building tradition dating back many centuries. Furthermore, natural wood materials age more subtly than plastic, fiberglass or vinyl, all of which tout permanence but often show their age within a generation When someone tells you a material is permanent, what they really mean is that it can’t be repaired. Just look at some old vinyl siding or replacement vinyl windows that were advertised on the basis that they would never need replacement!
As a point of comparison, the lifespan of a new vinyl window may be considerably less than a well-made wood window. Harnsberger, who has overseen the restoration of many crumbling historic buildings, advises: "With proper flashing, caulking, priming and painting to protect wood windows from the effects of the weather, well made wood windows will endure often beyond a century of constant use. Amortized over such a long period of time, the value of high quality wood columns, like wood windows, may be far greater than their fiberglass or vinyl counterparts."
In sum, for reasons of its ancient historical associations, its greater architectural character, and for its long term value (when properly maintained), the classical wooden column remains the preferred replacement choice for the Old House Authority. Save the fiberglass column for use in new construction projects in the next wave of the Classical Revival, if indeed one is forthcoming. For the authentic historic structures of yesteryear, replacement with matching, authentic wood columns is the better choice.