
Continued Professional Development (CPD) is compulsory for chartered members of the Royal Institute of British Architects (RIBA), helping members stay safe, capable and professional, building on existing knowledge and teaching new skills and specialisms. Ravago Building Solutions has created RIBA accredited online CPD modules to assist architects in completing this requirement. This accreditation means all our materials have been meticulously checked and received the stamp of approval from RIBA.
The Importance of Water Flow Reducing Layer in an Inverted Flat Roof

This CPD article will discuss how a Water Flow Reducing Layer, such as Ravatherm XPS X MK, is central to the thermal performance of an inverted flat roof – minimising heat loss due to the rainwater cooling effect. It explains the crucial role they play and how to properly account for their presence in U-value calculations. By the end of the CPD you should have a greater understanding of:

- Core principles of an inverted roof
- The difference between declared lambda and design lambda
- The role that a Water Flow Reducing Layer (WFRL) plays in an inverted roof
- How to perform a more accurate U-value calculation for an inverted roof taking into account moisture conversion factor