How to Build Basement Stairs

Building basements stairs can be a long and frustrating task. But by taking your time and following some basic tips and directions, you can have your new basement stairs built correctly and within a reasonable amount of time.

Preplan your stairs

Check with local building codes to see if there are any restrictions or guidelines that you must follow when building your new basement steps. Some areas require a certain slope to basement steps to make them safe to use. If you don’t follow local building codes and something happens, you could be liable. And quite often, if building codes aren’t followed, your home insurance won’t cover it if something does go wrong.

You need to check on how much space you have for the stairs and where they will be situated. Depending on where you want the stairs to end, and local building codes, you may have to build your basements stairs in an L shape, or with a small landing. The easiest option is building the stairs straight down.

Get the measurements for your basement stairs

First thing you will need to do is get the measurements for building your basement stairs. With the help of an assistant, measure the distance from your basement floor straight up to the subfloor of the floor above. This will be your total rise. Next, mark out where the stairs will end in the basement. Measure from that mark to the floor on the first floor. This will be the total run.

Convert the total rise into inches and divide by seven, which is the riser height. The answer will give you the number of risers that you will have in your staircase. If you end up with a number that is not a whole number (i.e. 15.7) just round up to the next number.

The number of risers will also give you the number of treads (steps) that you will need. If your calculation gave you 16 risers, then you will need 15 treads. What ever number of risers you have, subtract one to get your tread number. (Because you start off with a riser, you won’t need as many treads).

Convert the total run from feet to inches and then divide that number by the number of treads you will need. This will be the width required for your stair treads. Adding together the riser height and tread width should result in 17 or 18 inches.

Lay out stringers for your basement stirs

The stringers are basically the frame for your stairs. Using a framing square and square gauges, you will draw an outline of where you will need to cut to build your stairs. Using the proper measurements for the tread width and riser height, trace out where the stairs will fit in. Once done, double check to make sure that your measurements are correct.

Build your basement stairs

Nail in 1 X 12 inch skirt boards to where your stairs will end. Making sure to cut out small notches in the bottom of the stringers so that they fit, nail the stringers to the skirt boards.

Cut your risers and treads to size. Once cut, attach them to the stringers, making sure to attach them with both glue and nails to secure them.