How Much Rebar Do You Need for a Perform Wall?

Perform Wall

• A Perform Wall Panel is a proprietary panelized building system, consisting of insulated concrete forms, or ICF. The forms are composed of cement, polystyrene, water and other additives to make panels 10 feet by 15 inches high. The panels can be stacked vertically or horizontally, or in combinations. Reinforced steel bars, referred to as rebar, and concrete are placed in the hollow cells, creating a reinforced concrete wall. The result is a fire, sound and thermal barrier that's structurally strong.

Load-Bearing Capacity

• The load-bearing capacity of the walls can be adjusted to the requirements for the building, by adjusting the concrete mix and the amount of steel reinforcement. A Perform Wall panel has a compressive strength -- resistance to forces pushing on it -- about 56 pounds per square inch, or psi, and tensile strength -- resistance to pulling forces -- of 43 psi. Normal weight concrete used for fill is usually a minimum compressive strength of 2,500 psi.

Reinforced Steel

• The strength of the walls is gained from the reinforced concrete that's placed in the wall cavities. Concrete is weak in tensile strength, which is increased by adding steel reinforcement before the concrete is poured. The amount of rebar depends on the structural design for the building, which is prepared in compliance with building codes. The panels are usually bonded together with polyurethane foam with the rebar placed in the cavities beforehand.

Rebar Placement

• Rebar is placed horizontally and vertically in the panels after they're installed. Horizontal rebar is placed on the bottom of the horizontal cells and vertical rebar may be hand-centered, or installed as specified for the construction. The reinforcement may be supported by chairs or other devices, as required for correct positioning. Vertical rebar needs a specified overlap for each level. As a rule of thumb, the overlap is 5 times the diameter of the steel.