Blocks of flats
There are other issues to be considered in the case of flats:
• Each flat must be treated as a separate airtight environment, independent of neighbouring dwellings. Therefore
the air barrier will include walls to corridors and party-walls with other flats.
• There will be different airtightness ‘zones’ within the block – corridors, staircases and lift shafts, for
example. Some larger blocks may have plant rooms: these are not conditioned spaces and must be screened off from
the heated accommodation by use of an air barrier.
• In high rise blocks of flats, the stack effect and the wind effect will be enhanced and so the air leakage may
• High rise blocks are likely to be of frame construction. Therefore there is a need to seal where any steel or
reinforced concrete structural elements penetrate the cladding. For more guidance on how to achieve airtightness
when using frame construction, see the Further Information section.