Effective U-values (R-values) for Tapered Insulation

As energy codes become more stringent and better enforced it will become more important to properly calculate effective roof assembly U-values (R-values) for compliance. One area where effective U-values are commonly misunderstood is tapered insulation for low slope roofs or at the eaves of sloped roofs. This bulletin presents the theory and calculation methods used to develop tables of effective R-values for tapered insulation.