What You Need to Know Before You Start

Replacing a baseboard is a straightforward project that most homeowners can handle with basic tools and a few hours of time. The job breaks into three parts: removing the old baseboard, preparing the wall, and installing the new one. You do not need special skills or expensive equipment—a pry bar, hammer, caulk gun, and miter saw (or a handsaw if you do not have one) will get you through the work.

The hardest part is usually the removal, because baseboards are nailed or glued in place and can splinter or damage the wall if you rush. The installation is simpler: measure, cut, nail, and caulk. If your baseboard runs around corners or doorways, you will need to make angled cuts called miters, which takes a bit of practice but is not difficult once you understand the angle.

Key Takeaways

  • Remove the old baseboard by sliding a pry bar behind it and working slowly along its length to avoid damaging the wall or cracking the board.
  • Measure the wall length, add 10 percent for waste and mistakes, and buy baseboard in the same profile (shape) as the original if you want a seamless look.
  • Cut the new baseboard to length with a miter saw set at 45 degrees for inside and outside corners, and at 90 degrees for straight runs and butt joints against door frames.
  • Nail the baseboard to the wall studs using 2.5-inch finishing nails spaced 16 inches apart, then fill nail holes and gaps with caulk and paint.

Removing the Old Baseboard Without Damaging the Wall

Start by sliding a 2-inch or 3-inch pry bar (also called a flat bar) behind the baseboard at a low angle, close to a nail. Tap the pry bar gently with a hammer to work it behind the board. Once it is wedged in, slowly lever the bar downward—do not jerk it, because that will crack the baseboard or gouge the wall. Move the bar along the baseboard every 12 to 16 inches and repeat the process.

If the baseboard is glued as well as nailed, it will resist more. Keep the angle shallow and work your way along the entire length before trying to pull it free completely. Once it is loose enough to move by hand, carefully peel it away from the wall. If nails are still holding it, tap them out from behind using a hammer and a small block of wood to protect the baseboard.

After removal, scrape off any old caulk, paint, or adhesive from the wall with a putty knife. Fill any large gouges or holes with spackling compound, let it dry, and sand it smooth. A clean, flat wall makes installation much easier and looks better when you are done.

Measuring and Buying the Right Baseboard

Measure the length of each wall where you will install baseboard. Use a tape measure and write down the measurement to the nearest quarter inch. If a wall is 12 feet 6 inches long, write it that way—do not round to 13 feet, because that will leave you with too much material and wasted cuts.

Add up all your wall lengths and add 10 percent to the total. This extra material accounts for mistakes, test cuts, and waste. If your total is 100 feet, buy 110 feet of baseboard. When you shop, bring a photo or a small sample of your old baseboard if you have one. Baseboards come in different profiles—some are straightforward rectangles, others have grooves or rounded edges. Matching the profile makes joints less noticeable and looks more professional.

Baseboard is sold in 8-foot, 10-foot, and 12-foot lengths. Buy the longest lengths that fit your walls to minimize the number of joints you have to make. If a wall is 15 feet long, buy one 12-foot piece and one 8-foot piece rather than three 5-foot pieces.

Cutting Baseboards for Corners and Straight Runs

Baseboards meet walls at three types of joints: straight runs (where the board continues in a straight line), inside corners (where two walls meet at 90 degrees inside the room), and outside corners (where two walls meet at 90 degrees pointing into the room). Each requires a different cut.

For a straight run, cut the baseboard square (90 degrees) using a miter saw or handsaw. Measure from the wall to the wall and cut the board to that exact length. For an inside corner, cut both pieces at 45 degrees so they meet in the corner at a right angle—this is called a miter joint. Set your miter saw to 45 degrees, cut the first piece, then flip the saw to the opposite 45-degree angle and cut the second piece. Test-fit both pieces in the corner before nailing.

For an outside corner, use the same 45-degree miter cuts, but the pieces will point outward instead of inward. If you do not have a miter saw, you can make 45-degree cuts with a handsaw and a miter box, which is a straightforward wooden guide that holds the saw at the right angle. Practice on scrap pieces first—miter cuts are the trickiest part of the job, and a few test cuts will build your confidence.

Installing the New Baseboard

Start at one end of the wall and work your way along. Position the first piece of baseboard against the wall and use a level to make sure it is straight (not tilted). Nail it to the wall using 2.5-inch finishing nails—these are thin nails that leave small holes that are straightforward to hide with caulk and paint. Drive nails into the wall studs whenever possible, because studs hold nails better than drywall alone.

Wall studs are typically 16 inches apart. If you know where they are, nail directly into them. If you do not, use a stud finder (a straightforward electronic tool that costs $15 to $30) or tap along the wall with a hammer until you hear a solid thud instead of a hollow sound. Space your nails 16 inches apart along the length of the baseboard, and drive at least two nails per board. Sink the nail heads slightly below the surface using a nail set (a small metal punch)—this creates a small hole that you can fill with caulk.

As you work your way around the room, test-fit each piece before nailing it. If a miter joint is tight and fits well, nail it. If there is a gap, do not force it—pull the board off and recut or adjust the angle slightly. Small gaps can be hidden with caulk, but large gaps look sloppy and are hard to fix.

Filling Gaps and Finishing

Once all the baseboard is nailed in place, fill the nail holes and any gaps between the baseboard and the wall with paintable caulk. Use a caulk gun and explore a thin, even bead along the top edge of the baseboard and along any joints. Smooth the caulk with a wet finger or a caulk tool to blend it into the wall and baseboard.

Let the caulk dry according to the manufacturer's instructions—most brands dry in 24 hours. Sand any rough spots lightly with 120-grit sandpaper, then prime and paint the baseboard to match your wall or trim. If the baseboard was already painted, you may only need to touch up the new sections and the joints.

Check your work by running your hand along the baseboard. It should feel smooth and solid, with no gaps or loose sections. Miter joints should be tight, and the baseboard should sit flat against the wall from top to bottom.

When to Call a Professional

Most baseboard replacement is a do-it-yourself job, but a few situations call for professional help. If your walls are very uneven or wavy, a professional can shim the baseboard (add thin pieces of wood behind it) to make it sit flat and look straight. If you have ornate or custom baseboard that requires complex cuts or joinery, a carpenter can handle it faster and more accurately than a first-timer.

If you discover that the wall studs are rotted or soft when you nail into them, or if the wall is wet or moldy, stop and call a contractor. These are signs of water damage or structural problems that need to be fixed before you install new baseboard. Installing trim over a damaged wall will hide the problem and make it worse.

Frequently Asked Questions

Can I install baseboard over old paint or caulk?

No. Old caulk and paint will prevent the new baseboard from sitting flush against the wall, and it will look crooked or have gaps. Scrape off all old caulk and loose paint before you install the new baseboard. A putty knife and some elbow grease will do the job.

What if my walls are not straight?

Slightly wavy walls are normal. The baseboard will follow the wall's contour, and small gaps can be hidden with caulk. If the wall is very uneven—more than a quarter inch over a few feet—you may need to shim the baseboard with thin wood shims to make it sit straight. A level will show you where the high and low spots are.

Do I need to remove baseboards before painting the walls?

It depends on how carefully you want to paint. Removing baseboard takes time but gives you clean edges and makes it easier to paint the wall and the baseboard separately. If you leave the baseboard in place, use painter's tape along the top edge to protect it from paint drips.

How do I handle baseboard at a doorway?

Measure from the wall to the inside edge of the door frame and cut the baseboard to that length with a square (90-degree) cut. The baseboard will butt up against the door frame. If the door frame is not perfectly square, you may need to make a small angle cut to fit the board snugly.

What is the difference between finishing nails and regular nails?

Finishing nails are thinner and have smaller heads than regular nails, so they leave smaller holes that are easier to hide with caulk and paint. Regular nails have larger heads that are harder to conceal. For baseboard, always use finishing nails—they cost a few cents more and make a big difference in the final appearance.