Most flat roof applications will need some sort of rigid insulation. Whether you are trying to achieve a particular R-value, fire rating or slope rigid insulation assemblies are always factored into the cost of a flat roof project.
Typical code R-values for new construction in this state are between R-30 and R-38, which is usually achieved by 2 layers of flat stock polyiso board or XPS foam board.
Adding slope can be achieved using Polyiso, XPS or EPS. Most applications call for 1/4" per foot slope, but some may require 1/2" or even 3/8" slope. Check the specs, pick the product on the dropdown menu, and enter the square foot quantities you need.
