U-values on Domes 1-layer: 5,36. 2-layers: 2,68. 3-layers: 1,70. 4-layers: 1,24. 5-layers: 1,03. U-values on plastic bases: PVC some have 0,92 and some 1,00. Polyester base:0,94. And the New super-insulated bases:0,22 and 0,36!! And for Steel bases Standard: 1,00 and extra insulated:0,56 ! And for Wood: 2,20. So if you want to know the total complete U-value on a Roof Dome and Base , we have a program for this , contact us and we will give it to you !