Stair Riser Production
The Production of the Stair Risers
One of the challenges of producing these cast concrete stair risers is the creation of the molds that they will be formed into. The molds for these risers must be durable, low cost, and accurate. To produce these molds, I have chosen to use the high quality tools at a local community workshop called, TechShop located here in Pittsburgh on Penn Avenue at Bakery Square.
The Molds
The molds themselves will be accurately carved out of high density foam using TechShop’s computer controlled router. These molds will be reinforced with a plywood backing to assure that they remain flat during concrete curing. The molds will be lined with replaceable vacuum formed plastic liners to protect the foam and to create a smooth surface to cast into.
Reinforcing
There will be a steel rebar formed into the concrete to reinforce the body of each stair riser and their support tabs. These rebars will be suspended in the riser molds by support wires, placed into the mold prior to the concrete being cast. These wires will assure the accurate positioning of the rebars needed to provide maximum strength to the stair risers. These support wires will be cut flush with the back surfaces of the riser after the concrete has cured.
Ornamentation
There are many ways that these stair risers can be ornamented. One low cost option will be for the stair risers to be stained in one of many available colors. The stained canvas area of the stairs can then be masked with rubberized vinyl cut in various patterns, and then sandblasted in unmasked areas to reveal the original color of the concrete. Using this method the stair risers can receive geometric patterns or, as described above, the words to poetry.
