The experts at Quantum Insulation focus on corrected thermal calculations for inverted roofs and discuss some of the ‘nuances’ in compliance demonstration and U-value calculations. Regular readers of this column (yes, we do assume there are some!) may remember our April 2020 QI@QI titled ‘Crucial considerations in calculating U-values in Inverted roofs’. In case you don’t remember this first pandemic lockdown/furlough period article (which we were not fined for) it covered the use of a WFRL, the difference between Declared and Design Lambda values and ETAG 031. It also referred to the BRE and BBA recommendations. So why are we...