
Interior trim basics
The key to installing trim is learning how to measure, make miter cuts and cope baseboard. You'll need an accurate tape measure, a power miter saw and a coping saw. Buy a good-quality blade for your miter saw. The more teeth a blade has, the crisper the cut. An 80-tooth blade leaves a cut that’s as smooth as glass, making it well worth the investment. Coping saws have a narrow blade and tiny teeth that allow you to cut tight curves, and are available at any hardware store. Pick up a couple of spare coping blades - they break if they bind as you're cutting.
In this project, we predrilled the nail holes, which makes nailing easier and helps avoid accidental splits and bent nails. A pneumatic brad nailer and finish nailer will make the job go much faster and don't require predrilling, but are not absolutely necessary unless you're doing a large job.
1. Trim terms
Buying trim
Stock trim is available in a wide range of styles from most lumberyards and home centers.We chose a relatively wide (3-1/4 in.) beaded casing to go around the doors and windows. It’s 11/16 in. thick and costs $2.40 per ft. We used three components to create the base: a 1/2-in. x 3-1/4 in. “hook strip,” a 9/16-in. x 1-3/8 in. base cap, and a 7/16-in. x 3/4-in. base shoe. The three together cost $2.70 per ft. Combine other standard trim types to create wider and more detailed shapes.
If you don’t find a trim style you like or you’re trying to match a molding in an older house, look in the Yellow Pages under “Millwork.” Millwork shops can custom-produce almost any type of trim from most species of wood. Custom work, however, comes at a price; be prepared to pay as much as three times the cost of stock moldings, plus setup charges of as much as $200. In addition, you may have to wait four to eight weeks.
Most trim is made of solid wood or medium-density fiberboard with a wood veneer. Oak, pine, birch, maple and poplar are the most common types available. We chose maple for this project.
Sometimes you can find trim made of various types of plastic, most often prefinished in white, brown or simulated wood. This trim is far more stable than wood but cuts much the same, if not easier. What it lacks, however, is the warmth and varied grain pattern you can only find in real wood.
Trim is sold in a variety of lengths. Before going to the lumberyard, make a list of the pieces you'll need, adding a foot to each piece for cuts, then buy lengths that you can cut those pieces from without a lot of waste.
Prefinishing saves time
Once you get your trim home, sand and stain or paint the trim before you install it. This part of the project isn’t much fun, but it’s a lot easier to finish trim before installation, working on sawhorses, than afterward, lying on the floor with sandpaper and a staining rag. You can do a better job of sanding and finishing the pieces, with no danger of getting stain on the wall or floor. You can then apply the final coat of finish after you’ve installed the pieces and filled the nail holes, without worrying to much about coating the edges perfectly. Do all the finish work in a well-ventilated area.
Set up your saw in the room you're trimming
If sawdust isn’t a problem, cut your trim in the room where you plan to install it. Set up the miter saw in the middle of the floor with plenty of room on either side. Cover the floor with a tarp to prevent scuff marks and scratches. Use blocks the same height as the miter saw table to support long lengths of trim.
2. Mark a reveal line 3/16 in. from the edge of the jamb with a combination square. Use a sharp pencil and position the marks in the corners and about every foot along the jamb edge.
Use test pieces to get perfect miters
Check the miters at the corners with two short sections of casing cut at exactly 45 degrees (Photo 3). Even though the corners should be a perfect 90 degrees, often they’re not. In addition, if the jamb sticks out or is set back slightly from the wall, a 45-degree miter cut won’t fit tight. By holding the test pieces at the corner you can see exactly how your casings will fit. If you see a gap, adjust the saw slightly and cut both pieces at the new angle. Make small adjustments. Even one-quarter of a degree makes a big difference.3. Hold the test pieces on the reveal marks to check the fit of the miter in the corner. If the joint is even slightly open at the top or bottom of the miter, adjust the angle on the miter saw slightly, recut both pieces and check the fit again.
If the angle of the miter is accurate but a gap still appears along the face, the pieces are probably tipping back against the wall. Cut or file the backside of the miter (back cut). This allows the joint to fit tight on the face of the miter. Don’t worry about taking too much off the back; it won’t be visible.
Mark and cut the first side casing at the angle you established with your test pieces (Photo 4). Always cut the pieces a little long and check the fit; the power miter saw gives you the ability to cut very slight amounts off with a high degree of accuracy. When the inside angle of the miter lines up with the reveal mark on the top of the jamb, tack the casing in place.
4. Cut the side casing about 1/2 in. overlong and hold it in place on the door jamb along your reveal marks. Use a sharp pencil to transfer the top reveal mark from the head jamb to the side casing. Then cut the miter at the angle you established with your test pieces.
Avoid splits—predrill nail holes
With maple, oak and other dense wood, predrilling your nail holes in the casing is a must if you're hand-nailing (Photo 5). Even with a softwood like pine, it's best to predrill to avoid splitting a perfectly fit piece. Use a 1/16-in. bit for 4d nails, 3/32-in. for 6d nails and 1/8-in. for 8d nails. You can also use a nail with the head snipped off as a substitute for a drill bit. The same size nail you’re driving works best.5. Hold the side casing in place. Predrill nail holes every 12 to 16 in., using a drill bit about 1/32 in. smaller than the nail size. Stay 1 in. away from the ends to avoid splitting. Drive 4d finishing nails into the jamb and 6d finishing nails into the wall.
Tack the casing into the jamb first, then to the wall. Wait until you’ve fit all the casings before you drive the nails in completely in case something doesn’t fit right and you have to remove the trim to recut it. We used 4d nails for the jamb and 6d nails for walls. If you’re using thicker casing, increase your nail size one increment, using 6d nails in the jamb and 8d nails in the wall. Your nails should penetrate the studs and the jamb at least 3/4 in.
TIP
On wood with a strong grain pattern, place your nails in the dark portion of the grain to make them less noticeable.
With your first corner fit perfectly, set the top casing aside and check the second corner with your test pieces the same way you did the first. Once you have established the angle of the miter, hold your top casing in place and transfer the reveal mark from the side jamb to your top casing (Photo 6). Cut the miter, check your fit and tack in place.
6. Cut the corresponding angle on the top casing, leaving the opposite side at least 1 in. overlong. Check your miter at the second corner with your test pieces, and adjust if necessary to fit tight. Then mark the opposite corner on the top casing at the reveal, cut it and tack it up.
TIP
Match your pieces of wood so the grain pattern and color are similar at the joints.
After nailing the top casing, mark and cut the second side casing, leaving an extra 1/32 in. for fitting purposes (Photo 7). Slide the casing into place parallel to your reveal marks and check your fit. If the miter is tight and the length is a little long, trim a hair off the bottom at a 90-degree angle until you get a perfect fit.
7. Cut the second side casing about 1 in. long. Then hold the casing backward and parallel to the door jamb. Make a mark where the edge of the side casing intersects the upper edge of the top casing. Cut the side casing about 1/32 in. overlong. Slide the casing into place. Check your fit, and then trim it to its final length. Once the miter fits, nail the casing in place.
Pinning will hold the mitered corners tight
When your miters fit perfectly, “pin” the corners (Photos 8 and 9) to help align the two casings and keep the joint tight. Use your finger to press the casings flush with each other. You may have to slip a small shim behind one of the casings to align them. Next predrill the corners for 3d finishing nails, one from the top and one from the side (Photo 8). If your casing is less than 1/2 in. thick, you’ll have to predrill the corners before tacking the casing up.8. Align the miters and predrill a 1/16-in. hole for 3d finish nails, one from the top and one from the side. Hold a piece of cardboard against the wall to prevent marring the wall while drilling.
9. Drive the nails into the casing gradually, alternating between the two nails so the miter doesn’t slide out of alignment. Use cardboard again between the wall and the hammer to avoid marring the wall.
Finally, work around the door, driving the nailheads slightly below the surface with a hammer and a nail set (Photo 10). Nail sets are sold in various sizes; choose one that matches the size of the nailhead you’re using. Set the nails deep enough to hold nail putty: A good rule of thumb is half the diameter of the nailhead.
10. Tap the nails just below the surface with a hammer and a nail set.
Case A Window
There are two basic ways to trim a window. One way is to “picture frame” the window, so that all four corners are mitered. This method is common on most newer homes, especially with casement windows. The second way is to install a stool and apron. Basically, this is a small ledge (a stool) at the bottom of the window with a piece of casing (an apron) under it. This method is normally found in older homes and is more often used on double-hung windows.11. Trim a window by cutting and tacking the top casing first. Then fit the sides and finish with the bottom.
Trim a window using the same techniques as with a door. Mark your reveal lines, use test pieces to check your corners, and transfer the reveal lines to the casings for cutting and nailing. When you “picture frame” a window, however, install the top casing first (Photo 11), then the two sides, and finally, the bottom. Fitting the bottom is the toughest part, because you have to fit both corners at once (Photo 12). But if you use your test pieces and always cut the casing a little long, you shouldn’t have any problem. Cutting the piece long allows you to adjust the miters if you have to. Once the miters are tight, gradually trim a small amount off with your miter saw until you have the proper length.
Trim out a window with a stool in the same order as you would a door, but with a few added steps. Install the stool first, then one side, the top and the other side. Install the apron under the stool last.
12. Fit one miter on the bottom, then overlap the opposite miter and mark it. Cut the miter 1/8 in. overlong, slide the casing into place and trim it down gradually while checking the fit.
Install a Base
Begin by using a stud finder to locate the studs, and mark their location on the wall with a narrow piece of painter’s tape. Rough-cut the baseboard about 2 in. overlong and lay the pieces along the wall. Install the longest section first and work away from the ends until you reach an opening or door. This ensures that the last cut will be a simple 90-degree cut. (If you're installing one-piece baseboard trim with a profile, cope the inside corners - see below.)13. Rough-cut all the baseboards about 2 in. overlong and lay them in place around the perimeter of the floor. Start with the longest wall, cut the first piece to length and nail it into the studs with 6d finishing nails. Remember to predrill your holes. Continue around the room, cutting the inside corners at 90 degrees and butting them together.
In general, measure and cut each piece about 1/16 in. overlong to ensure a tight fit. If you don’t have a piece of baseboard long enough to cover the entire wall, splice two pieces with a “scarf joint” (Photo 14). Bow the casing slightly to fit between the walls and press it into place. This ensures a nice, tight fit. But don’t force the piece in. Trim a bit off and try the fit again.
14. If you have to splice two pieces on a wall, use a “scarf joint.” Cut a 30-degree angle on each piece; if the joint opens slightly, this angle will hide the crack. Select pieces with similar grain color and pattern so the joint is less visible. Always locate a splice over a wall stud.
15. If the drywall tapers in at the bottom of the wall or stops short of the floor, simply drive a screw at the bottom of the wall and turn it in until the head of the screw is at the same plane as the main wall. The head will prevent the baseboard from tipping in.
Continue around the room butting the inside corners . If one side of the corner tips in or out, use a drywall screw or shim to straighten it (Photo 15). When you come to an outside corner, use test pieces to find exact angles - usually slightly more than 45 degrees. Mark the lengths in place (Photo 16) and add shims if the wall tips in. Nail the pieces in place using 6d finishing nails. You can also put a small amount of glue at the miters and cross-nail them with 4d finishing nails, but remember to predrill to avoid splitting the ends (Photo 17).
16. Hold the base-board in place and mark the backside at the corner. Now cut the piece to length at the predetermined angle for an exact fit.
TIP
If you’re adding a base cap, as we are, overcut the miter slightly, leaving the backside slightly open (Photo 17). The front side will be tight and the cap will cover the gap.
17. Cut the second piece to length at the same angle. Predrill, glue and nail the outside corner.
Cut the base cap and base shoe with coping cuts
Install the base cap pieces in the same order as the baseboard. However, because base cap has a curved profile, you can’t butt the inside corners. Instead, make a “coped joint” by cutting off one piece square and cutting the adjoining piece to match the profile of the molding (Photo 20). Just follow the steps in Photos 18–21 and you’ll find it’s easier than it looks. Practice a few times on scrap pieces to get used to it.18. Run the base cap in the same order as the baseboard. To cope the inside corner of the base cap for a tight fit, first cut one end at a 45-degree angle as if you were cutting an inside miter.
19. Use a coping saw to cut along the edge of the profile left by the miter. Angle your coping saw back slightly (back cut) to get a tighter fit on the face of the profile.
20. Check the fit against the adjoining base cap in the corner.
21. Trim with a file or razor knife as necessary. After fitting the cope, measure the cap for length, cut the other end and nail it up.
Install the base shoe last. Base shoe is usually used on hard-surface floors to conceal any irregularities or gaps between the floor and the baseboard. Even if your baseboards fit perfectly tight to the floor, you can install the shoe to add another dimension to your trim. Install the shoe the same as the cap, mitering outside corners and coping inside corners (Photo 22). Be sure to nail the shoe into the baseboard, not the floor, so it won’t pull away from the baseboard when the flooring expands and contracts.
22. Install base shoe the same as the base cap, coping inside corners and mitering outside corners. Where the shoe meets the door casing, cut back the part that sticks out beyond the door casing at a 30 degree angle. Predrill and nail the base shoe to the baseboard with 4d finishing nails.
Finally, set all your nails and fill them with colored putty - the type that wipes in (either oil or water-based) and doesn't need sanding. Buy several different colors and mix them together as needed to match the wood color (Photo 23). This type of putty should only be put on wood after it's been stained and has at least one coat of finish - otherwise it won't match and may leave stains on the wood.
The last step is applying a final coat of finish.
23. Set the nails and fill the holes with colored putty to match the wood stain. We mixed two shades of putty together to get a good color match. Press the putty into the holes with your finger and wipe the excess off with a cloth.
TIP:
With light-colored wood, always mix the color on the light side; darker putty stands out.
More information
Make natural wood trim look perfectPainting woodwork
Trim nailer basics
Tips for perfect trim
How to install baseboard molding
Wood finishing tips
Remove nails without damaging trim
Install 3-piece crown molding
Coping tight joints
Do-it-yourself chair rail
Craftsman trim
Venetian plaster wall and chair rail
Build your own window cornices




























Sylvia G
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Untitled
Wonderful job on this.
Hasri Abdan
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Nice stuff
Beer
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Cool