How to Build a Staircase

As you learn how to build a staircase, get familiar with these basics:

A: Rise

• The distance from the floor to the top of the staircase.
• In this illustration, the total rise is 45 7/8 inches.

B: Top Step

C: Total Run

• The total run of a staircase is the total number of treads multiplied by the depth of the tread. You then add the nosing and riser thickness to get the total run.
• The run in this illustration is 60 inches.
• The total run has to be less than the total distance available where the staircase can be built.

D: Headroom

• The minimum clearance for a staircase is 6 to 8 feet overhead.
  

E: Tread

• The part of the stair you step on.
• The tread is usually at least 10 inches deep if the stairs have nosing.
• There should be no more than 3/8 inch of variance in depth between the bottom and the top tread.
• The typical minimum tread depth is 10.
• The boards used for the tread are usually 1 inch thick.

F: Nosing

• The part of the tread that protrudes over the riser.
• Each nosing typically overhangs the stair below by 3/4 to 1 1/4 inches.

G: Riser

• The vertical piece of wood between each tread.
• In this illustration, the risers are 7 1/2 inches.

H: Maximum Overall Rise of Step

• The rise of a single step should not be more than 7 3/4 inches.

Stringers (not pictured): The structures that support the treads and risers.

Note: Check your local building codes for requirements in your area before building a staircase.

Consistency is the goal. Variances between steps can cause people climbing the stairs to miss a step and stumble. The total allowable variance across the staircase is only 3/8 of an inch. A rise between 7 and 7-3/4 inches and a run depth of 10-11 inches are time-tested. People are accustomed to using stairs within these ranges.

Check your local building code for a full explanation of exact requirements as they may vary from what is stated here. This guide isn't intended to replace full knowledge of building codes.

Take accurate measurements and design the staircase before purchasing and cutting the lumber.

• The first step is to determine the total rise, which is the height of a stairway measured from the top of the subfloor at the upper level to the subfloor at the bottom level. Use a construction calculator or a contractor's app to enter the total rise.
• Next, you will need to calculate the number of stair risers. Then, divide the total rise by the target riser height of 7 inches to determine the number of stair risers your staircase should have. Round up to the next whole number to determine the actual height of each of the risers.
• The goal is to make all the risers identical in height, but not to exceed your local code's maximum height, which is usually 7-3/4 inches. To calculate this, simply divide the total rise by the total number of stair risers which will equal the actual riser height. If the numbers don’t work, try adjusting the number of steps up or down until the riser height falls within the range.
• The run, or depth, of each tread should be a minimum of 10 inches deep, and there will be one less tread than there are risers. Now, multiply the number of treads by the depth of 10 inches to get the total run. This is the total horizontal distance the stairs will travel from beginning to end.
• Knowing the total run will help you determine if you should add a landing. Add a landing with a few steps if the total run extends longer than the available space, or if the total rise is more than about 12-1/2 feet. Build the landing with a minimum of 36 square inches of flat flooring before the next set of stairs. You will essentially be building two separate sets of stairs.

With the calculations done, you'll be sure to purchase the correct amount of lumber. Get good quality 2x12 lumber that is straight dry and with very few knots. Or purchase laminated veneer lumber, or LVL.

To keep the steps evenly supported and prevent sagging, space stringers no more than 16 to 18 inches apart.

The example stairs have four stringers. Two outer and two inner. The inner stringers are placed 16 inches on center.

Skirt boards will be made from 1x12 lumber. Risers can be cut from 1x8 or 1x10, depending on the rise. Treads will be determined by the finished floor. Solid oak is a popular choice for finished wood floors. Other materials can be used if the floor is carpeted.

• Using a framing square with stair gauges, mark the dimensions for cutting out the notches for the rise and run.
• First, attach a stair gauge at the rise measurement on the narrow part of the framing square, called the tongue.
• Attach the other stair gauge on the blade or the wider side of the framing square where the run or tread measurement falls.
• Next settle the framing square on the board a few inches away from the end, making sure that the tread or run will be along the length of the lumber. Mark the lines for each rise and run.
• Use a circular saw to cut along the edge of the marks on the stringer. Don’t cut all the way to the intersecting point of the lines. Stop about 1/4 of an inch short of the opposite line then use a hand saw, reciprocating saw or jigsaw to finish the cut.
• Adjust the top riser measurement to account for the height of any finished flooring, so that the height of every step, top to bottom, will be the same.
• Now, cut the top of the stringer based on the stringer length calculation. For the bottom step, you'll need to square off the end so that it will sit flush on the ground floor. To do this, use the square to draw a line parallel to the top of the last step.
• Adjust the bottom riser cut on the stringer by the amount of the tread’s thickness. This is done because the very top step will be the finished upper floor, and there won't be a tread board. Also add the depth of any additional flooring material such as tile or carpet. Make sure the height is accurate. The stringer should sit flush with the floor and with the point at the top where it will attach to the existing structure, such as the header or a hanger board.

• Set the stringer temporarily in place to test fit. It also guides the measurements for the cutouts needed to fit the first stringer, which will be along the wall before attaching the stringer nearest the wall.
• Add a 2x4 to the stringer where the skirt board should sit. Now, use the first stringer to trace the outline for cutting the remaining stringers.
• Attach the stringers to the header board with the joist hangers or 3-inch screws or nails. In the example, the inside stringers are set 16 inches on center.
• If a landing is needed, cut and lay temporary treads so that you can move up and down the stairs to complete the landing. Measure, cut and attach the stringers on the landing using the same method as the long stringers.

With the stringers installed, you are ready to cut and install the skirtboard for the open end of the treads and risers.

• The first step is to install the 1x12 skirtboard along the wall. Set the skirt just deep enough to prevent an open gap and be sure to take into account the thickness of the tread and riser.
• Make your mark at the top and bottom of the run then use a level to mark the vertical lines. Snap a chalk line to mark the angle of the skirtboard. Extend a measuring tape along the chalk line to determine the length of the board.
• With the gauges on the framing square set to the rise and run, mark and cut the skirt board. If the skirt will meet a baseboard along the floor, make a vertical cut here at the tip so that it will correctly meet the baseboard.
• Slide the skirt board down against the wall and secure it by nailing it into the studs.
• Next, cut the second outside skirt, and temporarily tack it into place. Scribe the returns. This will ensure an accurate outline of each rise and run. Use a level to scribe the line for the vertical rise and continue this all the way up the board until the outline is complete.
• Cut the risers in the skirt with a 45 degree miter so it will meet the miter of the riser boards.
• Reset the saw to 90 degrees for the tread cuts, which will not need to be mitered.
• Stop the cut about 1/4 of an inch short so that the intersection can be cleanly cut with a jigsaw or multi-tool.

With the cuts completed, fit the outside skirtboard and nail it securely in place.

• Take accurate measurements for the first couple of risers then set the saw at a 45 degree angle for the cut where it will join the mitered skirtboard.
• Set the saw back to 90 degrees for the inside cut against the skirtboard along the wall. Prepare to install the first riser board by applying a bead of construction adhesive along each end of the stringers, followed by wood glue along both joining miter cuts.
• Now, attach the board, wipe away any extra glue and nail the joining edges together. Check that it's flush and level, then finish nailing the riser board with finishing nails.
• Measure, cut, glue and install the next riser board.

The next step is to cut the tread boards. There will be one less tread than risers since the top of the staircase will start with a riser below the upper floor landing. Treads must have either a built-in bullnose or rounded edge. Nosings are required to overhang at least 3/4 of an inch, but not more than an 1-1/4 inches. Temporarily dry fit the first tread so that a pilot hole can be drilled through the back of the riser and into the tread.

• Apply construction adhesive to each stringer where the treads will be fastened. This will create a tight bond and help prevent squeaking as the stairs settle.
• Apply a bead of wood glue along the back edge of the tread and then lay the tread into place.
• Next, screw the riser to the tread from behind by driving a screw through the pilot hole you've already drilled. This will pull the boards together and keep a tight connection.
• Finally, nail the tread to the stringer with finishing nails. Measure and cut the next set of risers and treads and then continue the process up to the final riser at the top of the stairs.

To finish off the project, you need to install a handrail. You can choose from many styles of newel post ball finials and railings.

• A common staircase width in a house will only require a handrail on one side, but wide staircases will require one on each side.
• A staircase with an open side, like the example, will require a guard rail.
• Hand rail brackets should be attached to wall studs to hold the rail securely.
• The height of the rail from the floor should be from 34 to 38 inches.
• The rail must stand at least 1-1/2 inches off of the wall.
• The rail itself should be appropriately sized so that it can be gripped. This dimension varies based on the rail design, but a round rail should be between 1-1/4 and 2 inches in diameter.
• The rail should be continuous for the entire length of the staircase.
• Guard rails should be at least 34 inches tall.
• Balusters or rails must be close enough to each other that a 4-inch sphere can’t pass between them.