The joinery in baseboard forms the foundation for nearly all the joinery in finish carpentry, which makes perfect sense because baseboard is meant to replicate the foundation—the plinth—of a classical column. Though casing is the first molding profile noticed in a home, and often the first molding installed in a home, baseboard is usually the first molding that an apprentice carpenter learns to cut, and for good reason. The first big challenge in finish carpentry is learning how to identify and cut inside and outside corners—both miters and copes.
Please don’t try anything you see in THISisCarpentry, or anywhere else for that matter, unless you’re completely certain that you can do it safely.
Understand Baseboard Joinery
Most carpenters are never taught how to recognize inside and outside corner miters. Instead, they’re assigned a closet in the back of a home and told to figure it out on their own. That’s a tough way to learn, and it explains why many carpenters never learn the simple basics of miter joints. Watch most carpenters at work, and sooner or later you’ll see them close their eyes and try to visualize the direction they need to miter a piece of molding. Learn these basic rules—the Short-point-Long-point Method—and you’ll never wonder which way to miter your moldings, even when you’re cutting them upside down and backwards (yes, crown molding is next!).
|1. For outside corners, the short point of the miter is always at the back of the molding, against the wall, and against the miter saw fence—for outside corners, you measure to the short point of the miter and you cut to the short point of the miter.|
|2. For inside corners, the long point of the miter is always at the back of the molding, against the wall, and against the miter saw fence. For inside corners, you measure to the long point of the miter and you cut to the long point of the miter.|
Cope Inside Corners
There are a few reasons why carpenters should always cope inside corners. Wood swells and shrinks throughout the year, depending upon seasonal humidity. Coped joints don’t open nearly as much as miters. Cope joints are also faster to install than miters—the pieces of molding don’t have to be cut exactly the right length; in fact, coped material can be cut a little bit long. You never have to caulk a coped joint, not like you do a poor-fitting miter, so your hands will stay cleaner. And coping inside corners is a sign of craftsmanship. Learn how to cope molding, and you’ll be a craftsman.
|1. Miter joints aren’t forgiving. If a wall is bowed, or a corner out of square, a miter won’t close tightly. Miters require extra fiddling time. And they have to be cut exactly the right length.|
|2. Bumps ruin miters. A common bump of drywall mud at the bottom of a wall will ruin a miter, making it tough to close the top of the joint, requiring shims, messy drywall cutting, and more fiddling time.|
|4. Coped corners fit tight. Even if an inside corner is out of square by three degrees, a cope joint will fit tightly without any wasted fiddling time.|
Make a Cutlist
For right-handed carpenters, walk into a room, pick a wall and move to your left. Carpenters who use a coping saw in their left hand might find it easier to move toward their right. You’ll see why when we get to coping.
|1. Measure pieces precisely under six feet. This piece measures 45 1/8 in. and has an inside corner on the left and a butt cut on the right.|
|2. Mark the cutlist. Write the measurement in the center of the cutlist and write a “B” on both sides. We’re coping all inside corners, so both ends are butt cuts.|
|3. Measure short pieces a hair short. Sometimes short pieces are hard to install. I measure them a little short, especially when they butt against casing. If you measure them too long, you might move the casing.|
|4. Mark the cutlist. This piece measures 7 9/16+. The + sign really means an extra 1/32 in. The left end is a butt cut; the right end is a Cope (C), which means it must be mitered first.|
|5. Measure long pieces a little long. Add 1/16 in. for walls over 8 ft., and add an 1/8 in. for walls over 12 ft., then bow and snap the pieces in for a tight fit.|
|6. Mark the cutlist. This piece is butt cut on both ends because the inside corner on the left will be covered by a cope cut on the next piece.|
Measure Long Runs Carefully
Measuring long runs is difficult and the learning curve is steeper, or at least it used to be. Here are a few techniques that make the job easier:
|1. Read a bent tape measure. Most carpenters learn the hard way how to read a bent tape measure—by trial and error. But it’s never exact and always requires a little guess work.|
|2. Use a block. Avoid bending a tape measure by cutting a block of baseboard exactly 10 in. long. Measure to that block and then add 10 in. (WHOOPS! That tape measure should be reversed!!)|
Miter Outside Corners
Outside corners must be mitered. Because of that, the joints must be cut precisely to fit the wall. Measure these pieces carefully and expect to spend some extra fiddling time at each corner.
1. Measure precisely. To avoid drywall mud build-up near the floor, always measure near the top of the molding—if necessary, trace a faint line across the top of the molding.
|For pieces up to 8 ft., measure outside corners precisely; for pieces longer than 12 ft., you can add a little if the molding is thin and flexible.|
2. Use a protractor. Outside corner miters must be cut at precisely the correct angle. Use a protractor to read the corner angle. Divide the corner angle in half to get the miter angle.
|This corner measures 86 degrees—it’s really out of square, which isn’t unusual at all.|
3. Mark the cutlist. This piece has an inside corner on the right, which gets coped, and an outside corner on the left (OC).
|The outside corner needs a 43 degree miter (2 x 43 = 86 degrees). In order to cut that angle, the saw will need to be set at 47 degrees. (For more information, see Jesper Cook’s article, “Miter Angles and Miter Saws.”)|
4. Measure the next wall. Be sure to hold your tape measure near the top of the molding and measure to approximately the same height on the outside corner.
|Avoid having to bend your tape by placing the butt end on the inside corner.|
5. Mark the cutlist. This piece has a butt cut on the left, since it’s the first piece into the inside corner, and an outside corner (OC) on the right.
|Always write the measurement in the center of the cutlist.|
6. Measure one room at a time. Too many pieces on a cutlist will make the measurements and corner notes too small and difficult to read. You’ll confuse one piece with the next.
|This wall is the most common one found in homes. It has two inside corners. The right corner will be coped and the left corner must be butt cut.|
I have a lot of fun cutting molding at my miter saw. You should, too. In fact, if you’re not having fun, something is probably wrong. Having a cutlist makes the job much easier. It’s also much easier if the baseboard you’re using is short enough to cut in-position at your saw. With the molding standing up against the saw fence, the right end of the molding is the right-hand corner, and the left end of the molding is the left-hand corner.
Cope Inside Corners
Coping inside corners isn’t nearly as difficult as people think. In fact, once the miter is cut, whether you use a coping saw or a jig saw, the cut can be made effortlessly—if you use the tools properly. Follow these directions and you’ll soon be coping molding perfectly. Make several practice cuts before attempting to cope a measured piece of molding. Remember, craftsmanship and safety go hand-in-hand: you can’t do fine work, and you can’t work safely, unless you clamp your work to a work bench, table, or work station.
Like every part of trim carpentry, there’s a few techniques that make installing baseboard a lot easier. But before you start kneeling on the floor, buy a good pair of knee pads or place a piece of carpet or foam beneath your knees.
Installing baseboard also forms a critical part of trim carpentry. The techniques used vary from wall to wall.
1. Fit the pieces tight but not too tight.
2. Use a block of wood.
|A snug fit is best. Don’t hit the molding with a hammer. Instead, use a short block of wood to nudge the molding into position. Often a little drywall mud built up in the corners is all that prevents a well-measured piece from fitting on the wall.|
3. Trace overlapping copes.
4. Notch overlapping copes.
|Once the angle of the miter is traced, set the utility blade on the line and wiggle it up and down, cutting the angle a little deeper. When the blade is about 1/8-in. deep, twist it sideways and the waste will snap out of the way.|
5. Position the cope.
|Now isn’t the time to lose patience. Don’t force the cope together, otherwise the overlapping miter might snap off! Use a 5-in-1 tool to lift the molding and align the cope joint before pushing the piece against the wall.|
6. Use a block.
|With the cope aligned, tap the back of the baseboard into position against the wall. A well-measured piece should be snug but not move the casing. The cope joint should close up almost water tight.|
Not all of finish carpentry can be taught through simple rules. Some of it must be learned through experience. Installing molding on long walls is one example. To get tight-fitting joints on long walls, carpenters frequently “pressure-fit” the pieces—they cut them a little long so the molding snaps into place and the joints “sound” perfectly tight. But learning just how much pressure to apply takes experience. Don’t be nervous. Experiment and you’ll learn, too.
1. Nail off baseboard at casing. Before pressure-fitting a long piece into position, securely fasten butt ends against casing. That’s the best way to prevent moving the casing. (See left photo, below.)
2. Snap in long pieces. Hold the center of long lengths away from the wall. Push the corner in, then remove your hand and let the molding snap to the wall. (See right photo, below.)
3. Mark for overlaps. Butt-cut ends do not have to be removed for notching. Just follow the miter with your utility knife and wiggle the blade in about 1/8 in. deep. (See left photo, below.)
4. Make notches deep. Don’t worry about cutting a notch too deep. (See right photo, below.)
5. Copes cover notches. A tight-fitting cope joint will always cover the notch.
Making tight-fitting miters on outside corners is critical. These joints are the first thing people see in baseboard, chair rail, or crown. Fitting outside corners requires a different set of techniques, and an “eye” for solving problems. Whenever you reach an outside corner, downshift into slow mode and start looking for anything that interferes with a tight-fitting joint.
1. Test fit every piece. Always test fit outside corners.
|Check that the cope fits perfectly, then make sure that the short point aligns exactly with the turn in the corner. Be prepared to trim a hair off the miter if necessary.|
2. Don’t waste mistakes. Mistakes happen! Rather than get angry with yourself and lose your patience (and then make more mistakes), say these magic words: “How’d I do that?” If you can understand why you made the mistake then you won’t make it again.
|Look back at my cutlist (See Miter Outside Corners, Step 4 and Step 5, above.) and you’ll see I wrote down the wrong measurement mark!|
3. Mark pieces in place. Some carpenters intentionally cut outside corners long so that they can mark them in place, without having to use a tape measure.
|Reverse the molding so the long point of the miter is touching the inside corner, and then track a line along the outside of the previous piece of baseboard.|
4. Solve problems. I’ve heard carpenters say that 90% of finish work is solving problems.
|If the miter won’t close, then find the problem. In this case, I can’t press the molding tight enough to the wall because of the drywall mud build-up near the floor.|
5. Scrape problems away. Use a 5-and-1 tool to scrape away drywall mud…
|…especially from inside corners that might interfere with fitting a nearby outside corner.|
6. Carve problems away. Don’t be shy! If corners have too much build-up, mark the top of the molding, then drive a 5-and-1 tool into the wall about 1 1/2–2 in. lower than the baseboard.
|Carve out the whole corner if that’s what it takes to make a tight miter.|
I like to fit baseboard before I begin fastening it. That way I’m not carrying a nail gun and hose with me while I’m fiddling with the drywall, notching inside corners, and generally preparing the molding.
|1. Fasten outside corners first. Some corners must be fastened as you fit the pieces. Long pieces that butt in to casing are one example; outside corners are another example. I use glue and 23ga pins to secure outside corners.|
|3. Fit all joints first. Never nail off any piece permanently until the joint is made with the next piece. You never know when you might have to lift a piece of baseboard just a little in order to get a perfect fit.|