How to Build a Staircase

As you figure out how to build a staircase, you need accurate measurements. Get someone to help you measure everything. Working with another person will help you get the most accurate dimensions possible. 

If you have to make measurements alone, use a reliable laser measure. 

The first thing to measure is the “rise” of the staircase. The rise is the total distance from the floor to the top of the staircase. You can usually measure the rise using a tape measure. Include the thickness of any carpet, padding or subfloor in your rise calculations. This will help ensure the finished staircase’s treads are evenly spaced and uniform in size.

Other important measurements are:

• The tread’s depth and width. The depth of a tread is from the edge to the riser. The tread’s width is the horizontal length from one side to the other. 
• The riser, which is the vertical piece of wood or space between each tread.
• You’ll need to figure out the number of stringers your staircase requires. Typically, a stringer is required every 18 inches. Staircases are usually a minimum width of 36 inches, not including the handrails. A 36-inch-wide staircase would require three stringers. There would be one on each side and one in the middle of the staircase.  

You will use your rise measurement to calculate the slope of the stairs. The stair slope is the walking angle of your finished staircase. It’s also called the “rise and run” of the stairs. A stair’s slope determines how easy or comfortable it is to walk up or down the staircase. 

There are many ways to decide on the best slope for your staircase design. Here are some basic guidelines for calculating stair slope:

• For a standard slope, divide your total rise measurement by the number 7. This is the standard riser height. 
• Many building codes call for stair slopes that have an angle of about 37 degrees.
• Make sure the slope is in compliance with your local building codes. Check with your building permit or community affairs office for more details.

It's important to note that building codes allow for a variance, usually the bottom step (or both the top and bottom step), in case the math does not work out as an even number for all the risers. Also, building codes have a minimum and maximum rise dimensions for treads. Be sure to check local code for minimum/maximum measurement requirements as they relate to risers and treads. When the riser dimensions can't all be the same, this variance will need to be accounted for. 

When starting the staircase construction, you’ll need to decide how the stringers will connect to the upper and lower floor. Stringers, also known as stringer board, are the outer part of the staircase housing. They keep the stairs secured on either side. Pre-cut stair stringers are available in a variety of sizes to make this part of the project a bit easier.

Cut a notch along the bottom of each stringer for space to position it over a pressure-treated 2 x 4 cut of lumber. Methods for attaching stringers vary by local building code and your specific situation.

Wedge the 2 x 4 between the bottom notches and secure it with wood screws. 

If not using joining plate hardware, a notch can be cut in the top of the stringers and laid across a ledger mounted to the face of the landing where the stairs terminate at the top.

Tip: If you prefer to make your own stair stringers, use a carpenter square or stair gauges. Cut notches out of the frame and cut out the shape. You can use a circular saw to do this.

Again, the tread is the horizontal piece that connects the stairs. The riser refers to the vertical space between steps. This space may be filled with a solid piece or be open.

• Use a circular saw to cut the risers to length and width, if applicable, of each tread.
• Secure the riser to the stringers with wood screws. Start at the bottom and work to the top. 
• Using a construction adhesive to secure the treads and risers is good idea. It will provide a more secure hold. The adhesive will also help prevent squeaking in the future, as the stair assembly settles into usage. 
• As you install one riser, position and fasten the corresponding tread.
• Carefully climb to the next riser. Repeat until finished.

A staircase handrail or railing is both an attractive and practical addition. Most staircases have railing or a handrail on both sides. Others may have a handrail on just one side. Very wide staircases can have a rail that is in the middle. You can build your own handrail or buy a pre-made one that fits the style of your staircase.

You can mount a handrail to a wall or they can be integral to the design of your staircase. Depending on where you build the stairs, you may need to install stair railings to remain compliant with building codes. 

When there are walls on both sides of the staircase, mounting handrails will be fairly simple. Creating a railing that is part of the design of the staircase is a more complex endeavor. 

A staircase is usually at least 36 inches wide, which does not include the handrails. There should be at least 36 inches between handrails on either side of the staircase. Posts are typically bedded into the ground to support the rails.

When building a staircase, check the local building codes. There may be requirements for handrail heights and how to anchor the rails.