Service Ducts
Find out the GFA treatment for service ducts
Last updated 6 June 2026
Service ducts, including the thickness of the walls, are included as GFA once at the lowest floor, if the vertical shaft is entirely a void space.
If the service ducts are slabbed over at every floor, the service duct at each floor is included as GFA. Non-load bearing fire-stop material to compartmentalise the service ducts are excluded from GFA.

Service Duct
