Measure the stair and purchase the railing
The design we chose slightly exceeds the building codes in many regions. We extended the railing beyond both the top and the bottom steps. While this isn't always possible, it allows you to grasp the railing sooner and hold on longer to maintain good balance. Before you go shopping for your rail, measure from the nosing of the top landing to the floor at the bottom of the stairs and add 2 ft. This is the length of rail material you'll need. You'll find code-approved handrail and the other materials you'll need at lumberyards and home centers. Hardwood rails like the oak rail we're using are more expensive. Pine and poplar rails cost less. In addition to the rail, you'll need handrail brackets, a package of two-part, 90-second epoxy, and about 4 ft. of 2x4. Buy enough brackets to install two at the top, one at the bottom and one every 48 in. between the top and the bottom.
Mark the studs and railing height
Start by finding and marking studs. In order to be safe, stair rails must be anchored securely to the wood framing behind the drywall or plaster. Here are a few tips for locating the studs. Start by inspecting the skirt board to see if you can detect a pattern of nails that may indicate studs. Then use a stud finder to verify the locations. Most studs are 16 in. on center, so once you find one, you can try measuring horizontally to locate the next one. When you find a stud, mark it with a strip of masking tape (Photo 1). We used blue tape for photo clarity, but easy-to-remove (low tack) masking tape would be a better choice to avoid damaging the paint or wallpaper. Mark every stud along the stairs plus one beyond the top and bottom risers. You'll decide later which ones to use. Studs aren't always where you want them. If no stud is available at the top, use metal toggle anchors to mount the bracket under the short horizontal section of rail. If the wall ends close to the top or bottom step, you won't be able to extend the rail. Instead simply return it to the wall.
In addition to finding the studs, you have to make marks at the top and bottom of the stairway to indicate the height of the rail above the stairs. To meet building code requirements, the rail should be mounted so that the top is 34 to 38 in. above the front edge of the stair nosings. We chose 36 in. Photo 2 shows how to find this point at the top of the stair. Repeat the process on the bottom step. Later you'll align the top of the rail with these marks and locate the rail brackets (Photo 7). Then you'll use the mark at the top to position the rail before you attach it to the brackets (Photo 7, close-up).
Cut the rail to length and fit the joint
The next step is to cut the rail and glue on the short horizontal section at the top. Since the rail runs parallel to the stairs, you can use the stair noses as a guide for cutting the rail to the right length and figuring the top angle (Photos 3 – 5).
Start by cutting a 45-degree angle on one end of the rail. This cut is for the short return to the wall. Rest the cut end on the floor and mark the top (Photo 3). Cut 16-degree angles on the rail and short horizontal sections. This is an approximate angle. You'll test the fit. Trim the cuts until you get a tight fit (Photos 4 and 5). Don't worry if you lose a little length on the rail. It'll just reduce the distance the rail extends at the bottom, which isn't critical. When you're satisfied with the fit, cut the short horizontal rail section to length with a 45-degree miter on the end. Make it long enough to extend a few inches past the next stud so you can add a handrail bracket under it.
Glue the joint with epoxy
The shallow angle makes it difficult to join the short and long rail sections with nails or screws. And dowels or other joining methods require a furniture maker’s precision. So instead we'll show you a simple method to join the two with fast-setting epoxy. Cut 2x4s on edge at the same angle as the rail and join them with screws driven at an angle (Photo 6). Then support the rail sections with the 2x4s as you press and hold the joint together. With 90-second epoxy, you'll be able to hand-hold the joint together long enough for the epoxy to grab. Concentrate on keeping the profiles exactly lined up and pressing the rails tight together to eliminate gaps. Then leave the joint undisturbed for at least an hour. Overnight would be better, since the epoxy doesn't approach maximum strength for at least 24 hours.
To protect the wood from epoxy that may ooze out, wrap the rail ends with masking tape (Photo 6). Trim excess tape flush to the cut end with a sharp utility knife. Then carefully remove the tape after the epoxy has set for five minutes. The finished joint will probably require sanding to even up the edges. Do this after the epoxy hardens.
Position the brackets and mount the railing
Photos 7 and 8 show how to mark the underside of the handrail at the stud locations and how to use these marks to align and attach the rail brackets. Position and install two brackets first, one close to the top and one close to the bottom of the rail. Photo 9 shows how to locate the exact center of the studs. This is an important step because the rail brackets must be centered on the stud or one of the two top screws will miss the framing. Shift the bracket slightly if necessary to center it on the stud. If you shift the bracket, make sure to adjust the height to keep the top aligned with the mark (Photo 8). You may have to patch a few nail holes, but this beats having a bracket pull loose. Install the top and bottom brackets first and mount the rail to them (Photo 12). Then add the bracket under the short horizontal section. Finally, sight down the rail and straighten it before adding the intermediate brackets.
Be careful when you drive the screws included with the brackets. The heads will break off easily if you don't predrill pilot holes. If you're driving the screws with a drill, mount the bit in a magnetic bit holder to extend it away from the drill. This will give you more clearance for driving the angled screws.
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Add the returns and finish up
With the rail mounted, it's easy to measure for and install the short pieces that return to the wall at the top and bottom of the rail (Photo 13). Measure from the long point of the 45-degree miter on the rail to the wall and add about 1/16 in. for a tight fit. Then cut the returns on your power miter saw. Cut them from longer pieces (at least 12 in.) to avoid getting your fingers too close to the blade. These returns are required by the building code, and for good reason. They eliminate the possibility that loose clothing or a purse strap could get hung up and cause a fall. Besides, they create a nice finished look on the ends of the rail. We attached the returns with wood glue and 4d finish nails, but you could also use the remaining 90-second epoxy. Once the rail is complete, you can take it off to paint or finish it by simply removing the screws from the U-shaped brackets. Since the screw holes are already drilled, it'll be easy to reinstall.