How to Install Baseboard Trim
Intermediate · 1 day
Baseboard is the trim that quietly makes a room look finished — and the gap between an amateur and a pro job is all in the corners. Outside corners get mitered; inside corners get coped, which sounds intimidating but is just cutting one piece to nest against the profile of the other. Coping beats mitering inside corners because walls are rarely a true 90 degrees, and a coped joint stays tight even when the corner isn't square. With a miter saw and a coping saw, a single room is a satisfying day's work.
What you'll need
- Baseboard trim (use the calculator to size linear feet including waste)
- A miter saw and a coping saw (or coping foot on a jigsaw)
- A finish nailer (15 or 16 gauge) or hammer and finish nails
- A stud finder, pencil, and tape measure
- Caulk, wood filler, and a putty knife
- Sandpaper and touch-up paint or stain
Steps
Measure and mark the studs
Measure each wall and run a stud finder along it, marking stud locations with light pencil ticks above the trim line. You'll nail into studs so the baseboard holds tight.
Plan your cut sequence
Decide which walls get square-cut ends, which get coped, and which get mitered, and where seams will fall on long runs. Cut a 45-degree scarf joint where two pieces meet on a straight wall so the seam disappears.
Start with a square-cut wall
Cut the first piece square on both ends to fit wall to wall, set it against the wall, and nail it into the studs near the top and bottom edges.
Cope the inside corners
For an inside corner, cut the mating piece at a 45-degree miter, then follow the exposed profile line with a coping saw, back-cutting slightly. The coped end nests over the face of the first piece for a tight joint.
Miter the outside corners
Cut each piece of an outside corner at 45 degrees so they meet at a clean point. Test-fit and shave the angle if the wall isn't a true 90; a dab of glue at the joint keeps it from opening later.
Nail it home
Fasten each piece into the studs, top and bottom, keeping the trim tight to both wall and floor. Set the nail heads just below the surface so they can be filled.
Fill, caulk, and touch up
Fill the nail holes and any joint gaps with wood filler, caulk the top edge against the wall, then sand and touch up the paint or stain for a seamless look.
Pro tips
- Subtract about 3 ft per doorway and add roughly 10% for miter and cope waste — the baseboard calculator does both.
- Cope inside corners, miter outside corners. Coping absorbs out-of-square walls that would leave an ugly gap in a mitered inside joint.
- Caulk the top edge against the wall but leave the bottom against the floor uncaulked so seasonal floor movement doesn't crack the joint.
- Cut a few practice copes on scrap first. The motion is quick to learn and makes the difference between tight and gappy corners.
FAQ
How much baseboard do I need?
Measure the room's perimeter, subtract about 3 ft for each doorway, and add roughly 10% for miter and cope waste. The baseboard calculator returns the linear feet to buy.
Should I cope or miter inside corners?
Cope them. Walls are rarely a perfect 90 degrees, and a coped joint stays tight where a mitered inside corner would gap. Save miters for outside corners.
Do I nail baseboard into studs or drywall?
Into studs whenever possible, top and bottom, so the trim holds tight long-term. Between studs you can catch the bottom plate, but drywall alone won't hold baseboard securely.
Ready to estimate materials? Use the Baseboard & Trim Calculator →