Basic Steps to Estimating ICFs
Much of the estimations we make in this section refer to square footage. As a general rule, remember that Square Footage is Length x Width (in inches) / 12. When calculating the square footage of ICF blocks you’ll take this same formula and replace width with height. So the square footage of ICFs needed in your wall will be Length x Height (in inches) / 12.
- Divide wall height by 16” and round up. This is the number of courses required.
- Multiply the number of 90° corners in the structure by the number of courses required. This is the number of 90° corner forms required.
- Multiply the number of 45° corners in the structure by the number of courses required. This is the number of 45° corner forms required.
Form Square Footage
The square footage of corner forms is different depending on if it’s an inside or outside corner. An inside corner has less square footage versus an outside corner because the panel lengths are different. To determine whether a corner is outside or inside, identify the long side of the block by adding the total length of the panels on one side of the block. If the longer side is on the outside of the wall it is an outside corner, if the short side is on the outside of the wall then it is an inside corner.
Use the chart below to determine the total square footage of all forms to be used.
Determining the Total Square Foot Area of a Wall Being Formed
Next, we will calculate our total wall square footage.
- Multiply the linear footage of structure by the height of the structure
- Subtract 80% of window and door openings
- Subtract total square foot of all 90° forms to be used and all 45° forms to be used
- Divide the remaining square footage of the wall by 5.33 to determine the number of straight forms required
- Add a small number of forms for possible waste.
