How to Build Square Wood Columns
Hand-made columns can be decorative elements on their own, or they can cover existing columns or objects, such as pipes or ducts. This type of column is strictly decorative; it is not structural, or load-bearing. A simple square column typically consists of four boards joined along their side edges to create a hollow structure. If you can build a box, you can build a column.
The biggest challenge when building a column is assembling long pieces of material uniformly along their entire length. Resolve the problem with nylon strap clamps. wrapping the column during assembly to apply pressure equally on all four sides.
It's possible to assemble a column using bar clamps, but you'll need a lot of them to apply consistent pressure along the length of the column. Setting all the clamps takes extra time, and the glue may set too fast, making it difficult get good adhesion on the joints along the entire length of the column.
The material you choose depends on your application. If your column is under 96 inches in length, medium density fiberboard (MDF) is an affordable, paint-grade material that's easy to work with. Use hardwood plywood for a mid-range column. If the column is over 96 inches in length, use poplar or fir lumber for economy, or hardwood lumber for a high-end look.
Step 1: Determine the Size
The width is subject to your needs, but the length should be at least 1/2 inch shorter than needed, so the column has room to clear the ceiling when it's tipped up. (You can use molding to cover the gap after the column is installed.)
Step 2: Miter the Sides
Cut four pieces of material using a table saw. Tilt the blade to 45 degrees and cut a mitered edge on both long side edges of all four pieces.
Step 3: Glue and Assemble
Place the four pieces across two sawhorses. Add a sheet of plywood across the top to stabilize the workpieces, if desired. If you need access
to the bottom side of the workpieces, remove the plywood. Apply glue to the mating edges of two of the column pieces. Place the pieces together to form an L-shape. Shoot 1 1/4-inch pin nails randomly where needed to secure the two pieces together. Use pin nails sparingly. Too many can affect the ability of the clamps to squeeze the pieces together evenly.
Place 3/4-inch wood braces inside if the column boards bow or become hard to handle. Nail the boards to the braces. If you're assembling it over an existing object, don't use braces.
Assemble the remaining pieces in the same fashion, if you're building a freestanding column. If your column will cover an existing column or other object, complete the assembly with the new column in place around the existing object.
Step 4: Add the Straps
Wrap the column with nylon strap clamps placed 12 inches apart. Use a 1/2-inch wrench to tighten the clamps until glue oozes out equally along all four sides. Use a dampened cloth to wipe off excess glue before it dries.
Step 5: Sand and Finish
After the glue dries, sand the column smooth using 100-grit sandpaper. Finish hardwood items with stain and lacquer or paint. Use paint on MDF, poplar or common fir. Or, optionally, use stain and lacquer on poplar -- you'll be surprised at how good it looks.
Install the column using brackets or thin wood blocks, or use wood shims to fill the gap at the top or bottom of the column and screw the column to the floor and to the ceiling or other structure above. Alternatively, you can allow for a large gap and slide a premade base and/or capital piece above or below the column, securing the column to the base or capital. Hide brackets, blocks or shims with baseboard at the bottom and cove or crown molding at the top.
Columns are typically wrapped with baseboard at the bottom, and quarter-round, cove or crown molding along the top.