By: Gene Rodriguez, III
Learning how to build deck stairs can be the trickiest part of building a deck. For safety, stairs must conform to a minimum size and connect sturdily to the deck itself. Although there is some math involved, it's mostly simple division and multiplication.
How To Build Deck Stairs Like A Pro
- Step-by-step. Deck steps are constructed out of two elements: stingers (the long side pieces that reach from the deck to the ground) and treads (the part of the stairs that you actually step on). The vertical distance between the deck surface and the ground is called the total rise and distance between the face of the deck and the face of the last tread is called the run. The vertical distance between the individual stairs (generally 6" to 8") is known as the riser.
- A little math. To determine the number of treads for your stairs, first measure from the deck surface to the ground to come up with the total rise. Next, divide the total rise by 7.5 and round the result-this number is the number of treads you will need for your stairs. For example, a total rise of 38" would call for 5 treads (38 / 7.5 = 5.07, rounded to 5). To find the riser height, divide the total rise by your tread number plus one. Using the example above, we come up with a riser height of 6.33 (38 / 5 + 1 = 6.33). To find the run of the stairs, multiply the number of treads (5 in our example) by the depth of the tread (two 2" x 6" boards will create an 11-1/4" tread). To follow our example, the total run of the stairs would be 56.25" ( 5 x 11.25" = 56.25").
- An open and shut case. You have two options when it comes to stringers. A closed stringer is a sold section of wood where the stair treads are supported by cleats or brackets. An open stringer is notched with saw-toothed edges that matches the rise and tread measurements of your stairs-the tread boards rest on the notches.
- Landing pad. The bottom of your stairs should rest on a concrete pad. The pad may be poured concrete or built of concrete block, depending on local building codes. You'll get a more stable foundation from a poured concrete block.
- Strung out. Actual construction of your stairs starts with marking the stringer boards. The easiest and most accurate way to mark the stringers is with a framing square. A framing square has rulers etched into both legs of its L-shaped body, making it easy to mark off both sides each stair notch. Following our example, the rise side of the notch would be 6.33", while the tread side would be 11.25". If you're building an open stringer stairway, the notches would need to be cut from the board, but for a closed stringer staircase, angle brackets would be installed just under the tread lines.
- Deck stair construction. To install your deck stairs, mark the location of the stair bottom and pour a concrete pad for a landing area. Next, install the stringers to the face of the deck using deck screws and angle brackets. Follow the stringer installation by adding the treads: either screw them into the tops of the stringer notches (for open stringers) or attach them to the pre-installed brackets (for closed stringers). Finally, the base of the stringers should be attached to the concrete pad using angle brackets and masonry anchors. Railing hardware should be installed per local building codes.
