Attach Stair Stringers: Tips and Mistakes to Avoid Attach Stair Stringers: Tips and Mistakes to Avoid

Stair stringers are the boards in a stairs that actually hold the stairs in place. The stair stringers are installed to run the length of the staircase. There are some mistakes to avoid and tips that will be helpful for you when attaching stair stringers. These suggested tips and mistakes to avoid should help you be successful in this installation. The tips and mistakes to avoid relate to the size of the stair stringer, how to properly lay the stair stringers out and how to properly install your stair stringers.

The Size of Your Stair Stringers

Choosing what size your stair stringer should be is an important consideration when installing them. You should choose a board for your stair stringer that is no smaller than 2 by 10 inches. This piece should be comprised of solid wood as oppose to a composite material that is less expensive. You want to leave a yield of 3 1/2 inches of solid wood from the cut out when making the stair stringers. This will give you the strength to support the weight of a person up to several hundreds of pounds in weight.

Attach a Vertical Post for Support

A way to support additional weight on the stairs you can add a vertical post to the stair stringer. A vertical post or 2 placed beneath the stair stringer will provide additional support that is needed for the stairs. Depending on the location of the stairs, you may also want to attach the stringer to a wall with nails.

Do not use less that a 2 by 12 inch stringer if it is not possible to either nail it to the wall or install a vertical post beneath it.

Laying out the Stair Stringer

There is a lot of precision that goes into laying out the stair stringer. For example, if you have a stair that has 12 rises on the stringer, if you make a mistake in the layout that is as much as 1/16th of an inch, this will result in the stair being off by 3/4ths of an inch (1/16 inch times 12 = 12/16-inch = 3/4-inch).

When you are laying out the stair stringer, use a framing square in the following way: your framing square consists of 2 sides, one that is 2 inches by 24 inches, which is the body, and the other that is 1 1/2-inch by 16 inches, which is the tongue. Hold the framing square by the shorter side or tongue and mark the run and rise of the stair stringer (elevation) using the markings on the body. It is best to practice using the framing square to make sure that the marking line up precisely. If you have problems using the framing square properly, go to a home improvement center for advice.  

Proper Installation of the Stair Stringer

When installing the stair stinger always measure from the top of the floor down. Be sure to add an allowance for the thickness of the stair thread itself or about 1 inch. Doing this will eliminate common installation problems that may occur.

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