How to Make a Scarf Joint Video

In this video, Mark Donovan of HomeAdditionPlus.com shows how to make a scarf joint using a miter saw.

When installing baseboard trim or molding, you may need to cut a scarf joint to join two pieces of trim or molding together. Scarf joints are typically used along long wall lengths where one piece of baseboard trim or molding is simply not long enough. Using a miter saw you can easily make a scarf joint.

To make a scarf joint first measure the length of wall to determine the amount of baseboard trim or molding required.

Then determine the best location for the scarf joint. Often the seam is made where it is less likely to be seen, albeit if done right the scarf joint will be nearly impossible to see anyways. Frequently a scarf joint is made somewhere to the left or right of wall center. Next, make sure the two ends of your baseboard trim or molding pieces are square. You may simply want to trim off their edges with a 90 degree angle square cut. Now cut one of the boards to the desired length, however on one of the ends make a 45 degree angle cut, across the grain. Use a medium grade sandpaper to smooth the cut edges.

Cut the second board to length, however on one of the ends cut it at a 45 degree angle in the opposite direction. By cutting this trim piece in the opposite direction you will be able to make a scarf joint, or lap joint, when placing the two trim boards together. Again, lightly sand the cut edges of the second piece of baseboard trim or molding.

Install the baseboard trim piece with the 45 degree angle cut facing inwards, towards the room center. Nail it to the wall using finish nails and make sure you nail it into wall studs. Apply a dab of wood glue along the open face 45 degree cut.

Next, install the second piece of baseboard trim such that its 45 degree angle cut overlaps the other baseboard trim piece. Again nail it into place and use a damp rag to wipe off any excess wood glue. Stain or paint the trim, and with that you’ve completed making a scarf joint.