Do It Yourself Decks: How To Build Stairs

Building deck stairs requires the cutting and assembly of stringers and treadsm and possibly risers.

A deck can be enjoyable and add value to your home, but not if people can't get on and off of it. Even some of the simplest decks can get complicated when it's time to build the stairs. This article should give you a general overview of how to go about this sometimes challenging aspect of deck construction.

Aside from the railing, a staircase consists of three elements: treads, risers, and stringers. Treads are the horizontal steps. Risers are the vertical boards that connect the front of one tread to the back of the tread below it. Stringers are the diagonal, sawtooth-shaped boards that support the whole structure.

The size and number of each element will of course depend on the height and width of the stairs to your deck. Many deck stairs omit risers entirely, in what is referred to as an open staircase. And if the steps are low and wide enough, a handrail isn't necessary. But without stringers and treads, you don't have stairs.

Pre-cut stringers can be purchased at most lumberyards, but it's also possible (and cheaper) to cut your own. The best wood for a stringer is a 2" x 12" plank because it provides the greatest structural stability. To make a stringer, cut regular diagonal notches in the wood to accommodate the treads. The notches should NOT be at exact forty-five degree angles. That's because your treads need to be wider than your risers are tall. Check building codes in your area, but a general rule of thumb is that treads cannot be narrower than nine inches, while risers cannot be higher than eight inches. Another thing to keep in mind is that at their narrowest point, the stringers must be at least 3 1/2 inches wide.

The easiest way to make sure your step notches are even is to cut a smaller piece of wood to use as a template. Simply cut a short, rectangular board that is your desired tread width on two sides, and your desired riser height on the other two sides. Line up the opposite corners along the edge of your stringer board to trace the lines where you'll need to cut.

The foot of your stringer will naturally need to be precisely parallel to the lines where your treads will go. Lay it out in such a way as to maximize the amount of wood that will make contact with the ground.

Make sure all of your lines are traced BEFORE you start cutting.

The number of stringers you need depends on the width of your stairs. You'll need, at minimum, a stringer along each side of the stairs. If the stairs are more than a few feet wide, you'll also need one down the middle. For extra-wide steps, you'll need a stringer roughly every three feet of width.

The stringers will naturally need to be solidly affixed at both ends before installing the treads. To attach the stringers to the deck frame, it's advisable to use either wood screws or special brackets designed for the purpose. Nails can work loose over time, especially as people pass over the stairs and their load shifts. IF you plan to attach your stringers to deck posts rather than the deck frame, there's an even better option: drill holes through the post and the stringer and attach them using heavy-duty carriage bolts with large washers. Use two of these per stringer.

As for the bottoms of the stringers, they cannot simply rest on the dirt; they must be attached to something solid. This can be either a concrete slab, or concrete footings set into the ground. Ideally, footing bolts should be inserted into the concrete while it's still wet, which will allow you to install footing brackets to which you can anchor the stringers.

If your stairs go to a second-floor deck, it's a good idea to attach support posts to the tops of the stringers. These posts should be anchored firmly to the ground, and attached to the stringers using carriage bolts. Another pair of support posts attached to the staircase's midpoint will add even further strength and stability.

One you have the stringers up, the hard part is over. If you want your stairs to have risers, now is the time to install them. That's because it's easier to drive screws or nails horizontally through them into the stringers before the treads are in place. Risers can be cut from wood one inch in width, because they don't serve a structural purpose. Don't bother leaving room for the treads to slide in under them; they should rest on the horizontal surfaces of the stringers. The most important thing to remember is to cut them all the exact same length and width, because the template you used to cut the stringers will ensure that the notches are all the same size. Also, it's better to cut them a millimeter too narrow than a millimeter too wide. If they're too wide, the treads will rest partially on them instead of squarely on the stringer, which will lead to squeakiness and instability. If you want an open staircase without risers, skip ahead to the treads.

Like the risers, your treads need to be exactly the same length and width. Cut them from wood at least two inches in width (an inch and a half in actual measurement), because they will be the only thing supporting people's weight when they step on any spot that doesn't have a stringer running immediately below it. Each step can be cut from one wide piece of wood, or from two narrower pieces. It's permissible and even common for the tread to have a slight overhang past the front of the riser immediately below it, but if that overhang is more than an inch it's likely to trip people up. When attaching the treads to the stringers, wood screws or spiral nails are your best option, to avoid having them work their way loose over time.

If your stairs run the entire width of your deck or there aren't more than two or three of them, a handrail may not be necessary. However, one is required if the stairs are steep, or if they go from the ground to an upper-floor deck. The easiest way to install a railing is to attach the vertical rail posts to the stringers. Rather than nails or screws, it's better to drill holes and use heavy-duty carriage bolts with wide washers to attach them. If the weight of a full-grown human hits your railing for whatever reason, it needs to hold. Rail posts don't need to be attached at every step; every three to five should be sufficient, depending on the sturdiness of the railing itself. Many railings feature decorative slats in between the structural posts. When placing these, make sure that they are either too close together for a child's head to fit through, or far enough apart that there's no way that head could get stuck.

These are meant to be general guidelines for constructing stairs to your deck. Building codes may vary in your area, so be sure to check.

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