How To Build Stairs

How To Build Stairs

Here’s a step by step method for planning, measuring and building stairs. Stair construction is simple and fun with the right formula.

First of all, I need to say that stair construction isn’t a job for complete novices. There is a certain level of carpentry experience needed to build stairs that are strong and attractive. If however, the project is a backyard deck or a playhouse that requires stairs, then this is a good time for those with less experience to learn. However if the new stair case is for an attic conversion, you would be advised to call in experts in the loft conversion field.

To simplify the process, building a stairway is very basic math. For example, a stairway needs to be a certain height, but it also needs to cover a certain amount of floor space. How many stairs will it require for a person to reach the desired level in a home? This is where the formula for making stairs comes in really handy.

Measure the height from the first floor to the second floor including the sub floor on the second floor. Take this number and divide it by seven. Seven is the average height of each stair. For example, if the height from first to second floor was 108-inches, divided by 7, the number would be 15.428. Drop everything after the decimal.

This tells us we need 15 risers to reach the upstairs. Now we take the height measurement and divide it by 15. For example, 108-inches divided by 15 equals 7.2-inches. On a tape measure, that converts to about 7 3/16-inches. This tells us that each riser height needs to be exactly 7 3/16-inches high.

Next, we will plan for the treads. This is easy. There is always on less tread than the amount of risers. This tells us to plan on having 14 treads. Each tread is around 10-inches wide. With those measurements in mind we can now determine our final measurement. This will be the length of the stairway. We multiply 14 treads by 10-inches. That tells us our stairway will be 140-inches long.

The width of the stairs is a matter of preference, but a stairway less than 36-inches wide would be too narrow to transfer furniture and bulky things.

Now we will need to build a stringer. Stringers are usually made from knot-free lumber. A 2×12 stringer is the most common.

Starting from the bottom of the board, measure up the height of the first riser. In this case we’ll say it’s 7 3/16-inches high. Using a carpenter’s square mark the board while it is lying on the floor. Go over 10-inches and then measure up to 7 3/16-inches again. Mark the measurement and repeat until the stringer has 15 risers.

Cut this out with a circular saw and a reciprocating saw to get into the corner of each stair. Once that stringer is finished it can be used for a template or a pattern for the other stringer or stringers. Attach each stringer firmly in place using floor joist hangers on the top floor for extra strength.

Once the stringers are in place, attach the tread plates with screws so they don’t squeak. That is all there is to building long stairs. If the stairway is in limited space it is usually a good idea to put in a landing.
Landings are popular these days. A stairway with a landing is easier to calculate if it is treated as two separate sets of stairs. This is the secret to making stairs with landings.