How to take off a slab on or below grade

During the creation of the surface model, SiteWorx/OS effectively creates a design line for all surface and basement elevations.

Depending on the information given, there are two ways to correctly take off the slab.

Given a slab with a surface elevation of 108 feet and the slab 4 inches above grade.

• Digitize the slab at an elevation of 108 feet.
• At the properties tab or the properties dialog, set Above Grade to 0.33. This adjusts the grade elevation to 107.67.
• Add fill layers as required.

Given a parking lot with top of curb elevation of 108 feet and a 6 inch curb height.

• Digitize the parking lot at an elevation of 108 feet. This is the grade elevation.
• At the layers tab, the first layer should be "Curb height" with a thickness of 0.5 feet.
• Add other layers as required.
• Adding the "Curb height" layer effectively lowers the parking lot surface to 107.5 feet. The "Curb height" will appear in the materials report, but can be ignored.