How to Build Stairs—A DIY Guide
Cutting the Stair
Now that we have directions on paper as to how to build our stair, it is time to begin cutting. Carpenters always measure twice and cut once, a good rule to follow when cutting stairs. Stair building can be expensive; you only want to purchase the materials once, so purchase and cut wisely.
When you start the project, make sure your work area is clean and well lighted. Working in comfortable surroundings makes a difficult task a little easier.
Lay out the stringers to begin the actual stair project. Do this by setting the rise and run of the stair on the framing square. The framing square clamps should be adjusted to 7 3/8 inches by 10 inches. Next, mark off the number of treads and risers that are needed for this stair. Always start with the first riser and end with the top riser, and draw in the second floor line. At this point it is helpful to count the number of risers so there isn’t a layout error. Repeat this procedure for all three stringers.
After you have marked the treads and risers, it is time for the final adjustments to the stair stringer. As with any well-planned work of art, tweaking the design may be necessary. In order for all of the risers to be in code-compliance, adjusting the top and bottom risers may be necessary. In our example when a 1-inch-thick tread will be added to the bottom tread cut, our bottom riser will be 1 inch too high. The opposite is true at the top. When we add the top tread, its thickness deducts 1 inch from the exposed riser height. To correct this situation we will deduct 1 inch from the bottom riser cut at the floor-level portion of the stringer.
After you have successfully laid out the stringers, cut off the triangular portions. A power saw is the best tool for this task, but be careful not to cut beyond your marked layout lines, which will weaken your stringers. The final cutting of the triangles can be cut out with a handsaw. After all three stringers are cut out, place them together to make sure they all match. Three perfect matches are what you want to achieve. Anything less than three perfect stringers and you may want to consider going back to the drawing board.
With three good-looking stringers on your bench, you can now take the left and right stringer and position them on top of the 1-by-12-inch skirt boards. On each skirt board, trace the cut where the stringer meets the floor and the top riser. Cut these lines out and also make a plumb cut on the bottom of this board at the height of the baseboard. Attach the skirt boards to the two stringers. These two stringers are now finished and can be nailed on top of the drywall. If no drywall is in place, fill out the stringers to the thickness of the drywall. Always, always, nail or screw to the studs. The center stringer is now ready to be mounted to the top header and attached to the blocking at the floor.
Now that your stringers are in place, it is time to double-check all of your cuts. Check the tread cuts for level and plumb. Check your measurements in every direction, left to right and front to back. Check the top and bottom riser–does it allow for the finish tread height? The top riser should offer a tread thickness of more than 7 3/8 inches and the bottom riser should be tread thickness less.
If after you have double-checked all of your cuts, and you are satisfied that you’re on the right path, it is time to rip the risers to the correct heights and nail them into place. Don’t forget to glue and nail them for long-lasting durability. Your treads should be 11-1/4 inches so they will not need to be ripped, just cut them to length, glue and nail into place.
Your stair is now complete except for the wall or handrail. Because our example stair is located between two walls, we will need to put a wall-mounted handrail in place to meet code compliance. Mount the handrail at 34 inches above the leading edge of the tread. It should be 198 inches in length and contain a wall rail bracket screwed into a stud or backing, every 4 feet. In the case of an open rail section to one side of the stair, it is easiest to mount the balusters on an angle cap.
You are now ready for inspection!
Stair building is an art. Do not expect to be able to learn it all in just one article. Many experienced carpenters have difficulties building stairs. So if you’ve pulled your hair out a little trying to achieve a quality stair project, you’re in good company. Be patient and with a little practice, you’ll be making your way up in the world on the steps you’ve just built.
Side Note 1:
1. To create a softer edge where the carpet breaks over the tread edge, route the edge with a 1/2-inch round overbite prior to installing the treads into the stringers.
2. If your material is spiltting, predrill your holes. This can also help prevent squeaking in the future.
3. Glue blocks can be placed at the underside between the tread and riser intersection.
4. Another very important but sometimes overlooked item is to seal the underside of your stair. This will prevent the stair from squeaking and warping.
Side Note 2:
Riser: Vertical surface between two treads.
Carriage stringer: Support for the treads and risers; usually cut to have the treads sit on the horizontal plane and the risers nailed to a vertical cut.