MKALLAY
SAWHORSE
I am looking at a project where the application of IECC (2018) Section C402.5.7 Vestibules is in question. One area of the project (Dormitory, mixed use) has what can best be called a tenant space - essentially a café - that is accessed directly from the exterior. This area is completely separate from the rest of the floor area, the entire tenant space is less than 3000 sq. ft., and so I believe exception 4 of the referenced section applies:
(Vestibules are not required for) doors that open directly from a space less than 3,000 square feet (298 m2) in area.
What is less clear is that there are entrance doors at a lobby space that is well under 3000 sq. ft., but that lobby is atmospherically connected to corridors and other spaces such that the aggregate area will exceed 3000 sq. ft. In this case, it seems to me that the intent of the code would be that a vestibule should be provided, even though the lobby itself is less than needed to meet the exception. Is this correct? And then - what if the lobby is separated from all other areas by doors that are normally kept closed? Would that meet the requirement? In other words - is the exception be based on the specific enclosed room that the entrance opens into, or does it apply to the entire floor area served by that entrance?
(Vestibules are not required for) doors that open directly from a space less than 3,000 square feet (298 m2) in area.
What is less clear is that there are entrance doors at a lobby space that is well under 3000 sq. ft., but that lobby is atmospherically connected to corridors and other spaces such that the aggregate area will exceed 3000 sq. ft. In this case, it seems to me that the intent of the code would be that a vestibule should be provided, even though the lobby itself is less than needed to meet the exception. Is this correct? And then - what if the lobby is separated from all other areas by doors that are normally kept closed? Would that meet the requirement? In other words - is the exception be based on the specific enclosed room that the entrance opens into, or does it apply to the entire floor area served by that entrance?
