Estimating Rebar
When estimating, it is important to choose the right grade and size of rebar. Rebar grade refers to the tensile strength of the steel and is measured in thousands of pounds per square inch. For an example grade 60 rebar will have a tensile strength of 60,000 pounds per square inch. Most all rebar used these days is Grade 60 rebar.
Rebar size refers to the diameter of the rebar and is measured in eighths of an inch. For example, number 5 rebar, a common size used in ICF construction has a diameter of 5/8 of an inch.
Below we will demonstrate how to estimate rebar for a single story structure using 10″ forms or less. When calculating, always round up to ensure there is enough rebar on hand.
For Horizontal Rebar
- First divide the Linear Feet of Wall by 0.9 to account for overlaps
- Divide that total by 20 to get the length of rebar needed per course
- Multiply by Number of Courses
For Vertical Rebar
- Divide the Linear Feet of Wall by the Vertical Dowel Spacing
- The multiply that total by the Wall Height of the structure
Even though you will estimate the full height of vertical rebar, vertical rebar is typically cut one inch shorter than the finished wall height. This allows for concrete to be screeded smooth and prevents any interference with the top plate. In multi-story construction, vertical rebar should be long enough to sufficiently extend into the wall of the next story.
