Hitting amazing levels of 0 13w m will need 300mm of mineral wool or 180mm of rigid foam.
Roof insulation level.
Your attic should have a certain amount of insulation in it and the recommended level of insulation for your attic is dependent on where you live.
Insulation level are specified by r value.
Upgrading existing roof insulation.
Achieving a u value of 0 20w m meaning your roof will be better insulated than your walls will need 120mm thickness of rigid foam or 200mm of mineral wool or natural insulation.
Rigid foam panels are available in thickness.
Inspecting your attic insulation.
The amount of insulation installed in the lofts of new buildings has steadily increased over the past half century from about 25mm in the 1960s to 270mm today.
Use rigid foam insulation panels on your flat roof before applying the final roof covering or inside the house before adding sheetrock or paneling.
The higher the r value the better the thermal performance of the insulation.
R value insulation chart find your zone on the map and then use the chart to determine the level of insulation you need to properly insulate your attic walls floors and crawlspaces.
R value is a measure of insulation s ability to resist heat traveling through it.