When considering the total run of the unit, local codes often require the top landing to extend at least 12 inches beyond the door swing. Subtract the width of an out-swinging door (usually 32 or 36 inches) from the length you measure between the foundation to the outside edge of the steps. If the remainder is less than 12 inches, you may need to change your plan. Be sure you know and understand the codes before you start planning concrete steps. If you don’t construct them according to code, a building inspector can make you tear them out. Codes may also include requirements about the placement of rebar or other reinforcements, as well as the concrete mix you use. Expect to spend two to three days to plan, lay out, and pour three concrete stairs (not counting curing time). Follow these step-by-step instructions to enhance your exterior with concrete steps. How to Compute Rise and Run The unit rise and unit run of steps are the individual dimensions of each riser and each tread. To compute the unit rise and run, first divide the total rise by 7 inches, a standard step height. Round up fractional results to the nearest whole number. Then divide the total rise again by this number to get the unit rise. For example, here’s the math for a total rise of 20 inches: 20 inches/7 inches = 2.8 (rounding up equals three steps). 20 inches/3 steps = 6.6 inches. In this example, you’ll need three steps 6-5/8 inches high to climb 20 inches. Next, divide the total run (to the outside edge of the door sweep) by the number of steps to get the unit run. For example, if your total run was 48 inches, here’s the math: 48 inches/3 steps = 16 inches per tread. However, a tread depth of 16 inches would probably feel too long. Adjust the tread depth to 13 inches, a more comfortable measure, and make the total run 39 inches. To pour concrete steps perpendicularly, start by striking a level line on the foundation to mark the height of the landing. Measure from this line to position the plywood forms for the rear and side. Brace the forms with stakes, cut beveled risers, hold them level, and mark their lower corner on the foundation. Then fasten the diagonal brace to the house and foundation and the risers to cleats. Brace the front edge of the risers as you would a straight stairs.