Builder's Tip: This DIY project may require another set of hands at times. Holding the 6' level or long straightedge while marking pencil lines is easier with two DIYers working together.
Builder's Tip: Most often, a single piece of top rail will not reach from one side of the wall to the other. Therefore, two pieces must be installed on the wall, creating a seam, or scarf joint, between the two pieces. With today's modern miter saws a square cut for an in-line joint will suffice, but over time, wood shrinkage will create a gap between the two pieces. To avoid the visible gap and to "hide" the seam, a bevel cut with the miter saw is made. Set the wood flat on the saw base, rotate the saw blade 45 degrees and make the first cut. On the second piece of top rail, another 45-degree bevel cut will be made in order to "slip" the end underneath the first cut. To make this cut, the top rail piece must be turned upside down on the miter saw base. The two 45-degree bevel cuts at the seam's two ends now create a scarf joint. This cut minimizes the seam's appearance and eliminates a wood shrink "gap" after wood putty is applied.