If you have an existing concrete pad such as a patio or a basement foundation and you want to pour concrete steps on top of the slab, you will find that the process is actually easier than installing concrete steps into dirt because the foundation for the steps is already installed. The concrete slab provides adequate support for the new concrete steps. Pouring concrete steps is a job for the DIY homeowner. However, check with your local building-permit and code office to ensure the steps you plan to install meet building codes for your area.
Position the concrete form onto the concrete slab and against the wall where you plan to install the new concrete stairs.
Coat the inside of the form with a concrete release agent. If you do not have a concrete release agent, you can use standard cooking spray. The release agent or cooking spray lubricates the mold and makes it easier to disassemble the mold when done.
Fill in the lower areas in the back of the mold with crushed limestone to reduce the amount of concrete you must use. In general, crushed stone is cheaper than concrete and helps to save money. It also speeds up the curing time.
Mix the concrete by following the instructions supplied with it. Use a concrete with a tensile strength of 4,000 PSI or stronger to ensure the steps will hold weight.
Overfill the concrete form slightly with the freshly mixed concrete. Slide a shovel into the concrete in the form to work the concrete into the corners and to expel air bubbles.
Rest a 2-by-4 board across the top of the form and use it to scrape the excess concrete off the top step. The board will level the concrete with the top edge of the form. Repeat this on each step, working your way down. Wait until the concrete turns a light grey before moving on.
Slide a concrete edging tool across the front edge of each step to give it a smooth, rounded shape.
Level the surface of each stair with a flat trowel. Use a circular sweeping motion and overlap each stroke by 50 percent to ensure adequate coverage. This smoothes out the rough texture of the concrete.
Approximately 24 hours after pouring the concrete, remove the screws that hold the sides of the concrete form together with a screwdriver. With the sides removed, lift the top section of the concrete form off the steps.