Minimum ventilation requirements based on dwelling air-tightness

C.1 The minimum requirements for permanent ventilation for certain appliances depends on a knowledge of the air-tightness of the dwelling where they are to be installed. Dwellings built after 2008 are likely to have evidence of the air-tightness either through an individual air permeability test certificate or through representative testing of the same design of dwelling on the same housing development. C.2 Older houses are unlikely to have been tested and may not always achieve an air permeability of less than 5.0 m³/(h.m²) at 50 Pa unless the building fabric has been substantially upgraded. That would include all or most of the following measures: • Full double (or triple) glazing • Effective closures on trickle vents and other controllable ventilation devices • All external doors with integral draught seals and letter box seals • Internal and external sealing around external doors and window frames • Filled cavity or solid walls • Impermeable overlay and edge sealing of suspended ground floors • Careful sealing at junctions between building elements such as between walls and floors or ceilings • Careful sealing around loft hatch • Careful sealing around chimney or flue penetrations • Careful sealing around internal soil pipe and overflow pipe for WC • Careful sealing around domestic water and heating pipes passing into externally ventilated spaces • Careful sealing of all service penetrations in the building fabric (electricity, gas, water, drainage, phone, TV aerial, etc.) • All cable channels for light switches and power sockets sealed • All cable entry for lighting and ceiling roses sealed. Recessed lighting should not penetrate ceilings separating loft spaces.