How to Curve a Wood Baseboard

Baseboard runs in residential construction of the past 50 years have been mostly arrow-straight. In older houses that pre-date the mass-produced tract era, curves were more common. A smooth, convex bend often described baseboard corners instead of a hard, 90-degree angle. If you're stuck in this century replacing curved baseboard from the early part of the last, you'll have to learn to bend. For the do-it-yourselfer, wood is usually bent in two ways: steaming or kerfing. Steaming requires a steam box, time, patience and occasional scalded fingers. Kerfing -- cutting small slots of wood out of the backside of the baseboard to make it bendable -- can be accomplished with a table saw and a kerfing blade.

Measuring tape
Table saw
3/32-inch kerfing blade
1 3/4-inch baseboard nails
Polyurethane wood glue
Wood putty
Putty knife
Wood stain

Instructions

- 1
  Select prime hardwood baseboards with straight, clear grain and no defects that will cause splitting.
- 2
  Measure and cut the baseboard in a length sufficient to span the curve.
- 3
  Determine the correct kerf spacing. Cut a stick of lumber of the same thickness and approximate hardness as the baseboard material. Measure and mark the radius of the curve to be spanned. Using a table saw with a kerfing blade, cut a standard 3/32-inch kerf three-quarters of the way through the thickness of the stick at one end of the marked radius. Secure the stick at that end, and the apply enough bending pressure on the other end to close the kerf. Measure the deflection of the stick when it is bent. The result is the proper amount of equal spacing between kerfs.
- 4
  Measure and mark the placement of kerfs to span the entire curve, on the back of the baseboard material.
- 5
  Cut the kerfs into the baseboard with an 8-inch table saw equipped with a 3/32-inch kerfing blade. Set up the saw to cut across the entire width of the baseboard and through its thickness, to within 3/16 inch of the surface of the other side.
- 6
  Test-fit the baseboard in place. Bend it around the curvature and mark the spots where additional full cuts must be made, such as lap cuts to meld it into adjoining straight baseboard or straight cuts to butt against a door frame. Remove the baseboard and make the necessary cuts.
- 7
  Apply a coat of polyurethane wood glue to the wall and the back of the baseboard with a putty knife.
- 8
  Press the baseboard into place on the wall, working the kerfed portion around the curve to fit. Secure with 1 3/4 inch baseboard nails -- spaced up to 4 inches apart vertically and 10 inches apart horizontally. Do not drive nails into the kerfs.
- 9
  Place weights or pressure blocks against the baseboard overnight to set the glue.
- 10
  Apply wood putty with a putty knife to seal kerf slots visible from the top of the baseboard. Allow the putty to dry overnight, then sand it to a smooth finish.
- 11
  Stain or paint the curved baseboard to match the existing baseboard.

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