The pitch line, an imaginary line that runs from the lip of the bottom stair to the lip of the topmost step. The “pitch” of the stairs is the angle between the base of the stairs and the pitch line. The rise, which is the total height of your staircase from its base to the topmost step. The run of your stairs, which is the depth of your stair measured from the front of your staircase to its back. The stringers of your stairs are the side supports to either side of each step. The measurements for your stringers will be used in the creation of your concrete forms. [1] X Research source
Measure the run of the steps by finding the distance between the frontmost and backmost part of the stair. Find the width of your stairs by measuring the distance between the leftmost and rightmost bounds of your planned steps. [2] X Research source
If this number comes out as a decimal, you must round up to the next whole number. If your stairs are built so the topmost tread is a step below the level/floor you are building up to, the number of treads you need will be 1 less than the number of risers. Otherwise, you will need an equal number of treads and risers. There are many online sites that offer simple step calculators to simplify this process. You should be able to find these through a general Internet search for a “stair calculator. " These calculators will help you determine the exact specifications of your steps, including the number of treads, height of each riser, stringer length, pitch line, and so on.
Add the rise multiplied by itself and the run multiplied by itself together, and then take the square root of that number. Finally, find the angle of your stringers by taking inverse sine (sin-1) of your total rise divided by the length of your stringers. It may be easiest to use a calculator, phone, or online calculator to find the length and angle of your stringers. The square root symbol will look like a check mark or a check mark with a horizontal top (√). [3] X Research source
Measure from corner to corner to ensure that your layout is properly squared up and the dimensions are correct. To make sure that your stakes are evenly lined up, run a length of string between the stakes around the perimeter and use the string to verify your stakes are aligned properly. Not running a line between your stakes to keep alignment can lead to more work on your part. In the worst-case scenario, a poorly aligned perimeter can result in a slanted/angled finished product. [4] X Research source [5] X Research source
This excavation is intended to clear away rocks, trees, grass, shrubs, and anything else that might interfere with your concrete pouring. You’ll also have to lay a sub-base upon which the concrete will rest. Since your sub-base should be at least 4-8” (10. 2-20. 3 cm) thick, you’ll need to dig down at least this far or the rise of your first step will be larger than you plan. [6] X Research source
Use 2 in × 6 in (5. 1 cm × 15. 2 cm), 2 in × 8 in (5. 1 cm × 20. 3 cm), or plywood that’s 3⁄4 in (19 mm) thick. Your form should exclude the top and bottom of the entire stair. The ground-oriented side of your stringer forms should be cut to meet the pitch line (angle) of your stair, and the top should be cut in a zigzag fashion to follow the rise and depth of each tread (step). If you are pouring concrete steps that form a right angle (L-shape), your stringer forms will not need to be cut on an angle. In this case, your stringer will follow the entire run and rise of your stairs. You should shave a slight angle into the bottom of each rise form board, excluding the bottom riser form board. This way, when you pour your concrete, you’ll be able to easily smooth the area in the corners of each step.
Screw 2 in × 4 in (5. 1 cm × 10. 2 cm) planks into the form and fasten them to the ground with wooden stakes to prevent the form from bowing out. Space your stringers to be approximately the planned width of your stairs apart. Then you can lay the riser form boards along the zigzags of the stringer that matches the upward rise of each step. Now you should be able to easily use your power drill to attach each riser form board to the stringer form boards. If your stairs form a right angle (L-shape), you should be able to lean them against a sturdy object base down so each stringer form is oriented like a normal stair. You may have to place a board between the stringers to stabilize them until you screw your first riser form board into place. Be sure there are no gaps in your form and that the boards line up evenly. Any gaps can lead to concrete leaking through your form, and unevenness will result in uneven steps. When you look at your form from the side, it should look like finished steps.
After placing your subbase, you’ll need to tamp it down until it is packed extremely firm, level, and stable. Use a long flat board and a level to check the levelness of your subbase. Smaller projects can likely be done with a hand tamper, which is essentially a heavy, flat metal plate attached to a wooden handle. Larger projects might require you to use a plate compactor machine. Failing to lay a sturdy subbase can result in cracking, deterioration, or structural failure in your concrete steps. Your concrete’s strength depends on a solid subbase. You may want to lay a thick gauge wire mesh on top of your subbase to reinforce the concrete you’ll be pouring. The idea is, even if your concrete cracks, the mesh will hold it in place so integrity of your stairs is maintained. [7] X Research source If you live in a colder climate, you can apply a layer of Styrofoam 2 inches (5. 1 cm) deep before adding gravel so frost doesn’t freeze underneath your steps and damage them.
You may want to give your form a very slight downhill angle. This way, when it rains, the water will run off your steps.
The top of the rebar cage should be at least 2 inches (5 cm) under the height of the finished steps. Use bolt cutters or an angle grinder to cut the rebar pieces to the right length. You will need a pigtail twister to secure the wire ties.
Smaller projects, like building a single step, might be possible without a cement mixer. You could mix your concrete by hand in a wheelbarrow. Another alternative is to create a mixing box (also called a mortar box) by using scrap/low-grade wood to create a makeshift reservoir where you can mix your concrete. [10] X Research source Add colorant to your concrete before mixing it to permanently change the color.
If you use a wooden plank or board, it should be as straight as possible and free of warping and other irregularities. These can create gouges or leave the surface of your concrete uneven. [11] X Research source
Smaller projects might only require the use of a handheld magnesium float. These kind of floats are extremely durable and are designed to slide across the surface of your still-liquid concrete easily. To use a bull float, push it away from you across the top of the concrete while keeping the back end of the float slightly elevated, then pull the float back towards yourself, keeping the front end slightly elevated. Float the entire surface of your concrete thoroughly. If you have used a bull float, you should use a handheld magnesium float to go over the surface once again when finished. Use long, sweeping motions for best results. At this point, it is not uncommon to see water bleed to the surface of the concrete. [12] X Research source [13] X Research source
Use light pressure when doing this; grooves that are too deep will cause water to puddle on the concrete, and could compromise its integrity. If you notice clumps of cement forming on your broom, this is generally a sign that you are adding traction too soon. Smooth the concrete once more with your handheld magnesium floater, and wait until later to brush your surface. [14] X Research source Wait to do this until the concrete has dried enough that you no longer see water seeping (or “bleeding”) out onto the surface. Otherwise, brushing will result in grooves that are too deep.
You can improve the curing process by applying a concrete sealer after pouring the concrete. Follow the directions on your sealer for best results. You should be able to remove your forms after a single day. Carefully remove your screws and take apart your form. After a few days, your concrete will be strong enough to walk on, though not fully cured. Enjoy your new concrete steps!
