We are increasingly encountering a recurring issue: a perceived clash between ventilation air transfer requirements and fire door specifications - particularly in flats. We are finding that intended ventilation air paths are being blocked because air cannot transfer between rooms as designed. Internal fire doors are fitted tightly into their frames with minimal threshold clearance, leaving no effective air path. Ventilation systems, whether natural ventilation or, more commonly, MEV or MVHR, rely on those transfer paths to connect supply rooms (e.g. bedrooms and living areas) with extract rooms (e.g. kitchens and bathrooms). Without them, ventilation is restricted in the rooms…

When I first became involved in shaping the airtightness requirements for Part L of the Building Regulations, the topic was treated as a specialist curiosity. Airtightness was often seen as a compliance hurdle rather than a fundamental element of energy efficiency, comfort, and building durability. Over the last two decades, the industry has come a long way. New homes are now tested, airtightness targets are clearly defined, and there is a growing supply chain of testers and products designed to make compliance achievable. In many respects, this is a positive story: UK homes are significantly more airtight than they were…

I have worked in building performance for over 30 years, and since 2008 have been closely involved in shaping ventilation policy in England and Wales. Having contributed directly to the 2010 and 2021 editions of Approved Document F, I have seen first-hand how regulation has evolved to respond to tighter fabric standards and the drive to cut greenhouse gas emissions, lately net-zero. 2010: A step change The 2010 edition of AD F was the first to make an explicit connection between airtightness and ventilation system choice. The principle was clear: as buildings become tighter, reliance on infiltration is not acceptable.…