Finish a Baseboard Run With a Mitered Return Instead of a Square Cut

The Problem

Where a baseboard run ends at a door casing, the casing is often thinner than the baseboard. Cut the baseboard square and the end grain faces into the room with the moulded profile — the ogee, bevel, or bullnose along its top edge — sliced through and exposed. Painted, that end grain absorbs more than the faces do and dries to a different sheen, so the cut stays visible after two coats.

The same thing happens where baseboard dies into a cased opening, a hearth, or a stair skirt.

The Technique

A return closes the profile by carrying it around the end of the board and back to the wall.

1. Cut the end of the baseboard at 45 degrees, with the miter opening toward the wall — the same cut you'd make for an outside corner.
2. Cut a matching 45 on a piece of offcut from the same stock, then cut it off square a few millimetres behind the point. You want a small triangular wedge whose mitered face mirrors the one on the board, and whose profile matches because it came from the same length.
3. Dry-fit the wedge against the board. The two mitered faces should close with no gap and the profile should run continuously around the corner.
4. Glue the wedge on. Don't nail it — it's too small and it will split.
5. Hold it with a piece of painter's tape stretched across the joint until the glue sets.

The board now ends in its own profile, with no end grain showing.