Simple Deck Stairs Installation

Take Careful Measurements

• Before installing your deck stairs, take careful measurements so you know the number of stairs required, the step rise, the depth of the treads and the staircase's span. To determine the number of steps, measure the vertical drop from the edge of your deck to the ground and divide the number by seven, rounding to the closest whole number. Identify the step rise by dividing the vertical drop by the number of steps. In most cases, it's not necessary to measure for the depth of the treads because standard 2-by-6s are used, which measure 11-1/4 inches wide. For the span, multiply the depth of the treads by the number of treads, which is one less than the number of steps.

Install the Posts

• With standard deck stairs, stringers form the sides of the staircase and support the treads. The posts anchor the stringers and are placed approximately 18 inches back from the end of the staircase. Use a pencil to indicate where you will attach the stringer to the deck to determine the staircase's end point. Once you know where the staircase ends, figure out where the posts should go by measuring back 18 inches. Dig holes and pour concrete inside to create footings for the posts. Set metal post anchors into the footings and attach the 4-by-4 posts.

Install the Stringers

• While you can cut your own stringers, purchasing pre-cut, notched stringers from a home improvement store is easier and allows for faster installation. However, you must remember to treat the cut edges of these stringers with a sealer-preservative to ward off rot. Use lag screws to attach tread cleats along the stringers where the treads will go. It usually helps to drill pilot holes so the screws do not split the wood. At the top end of the stringers, use joist hanger nails to attach angle brackets. Place the stringers against the edge of the deck so they are flush with the deck floor. Use more joist hanger nails to connect the stringers to the deck through the angle brackets. With lag screws and washers, use a ratchet wrench to attach the stringers to the posts.

Install the Treads

• Determine the width of your treads and use a circular saw to cut a pair of 2-by-6s for each tread. Place the front tread on the cleat so it is flush with the edge of the stringers and attach it with lag screws. Place the rear tread behind the front so there is a slight space between the two. Use additional lag screws to connect the treads to the back portion of the cleats.