vestibule doors

[Mr. Inspector]

Inspecting a existing building with interior alterations only. Walls were taken down to get a room over 3,000 sq ft which requires a vestibule. A vestibule was built with non insulated walls or glass on the interior, and with an regular wood and glass interior uninsulated door with no seals. Door has no auto closer but is required to have one per code. Outside walls and doors not changed. I can't find anything in the 2018 IECC that requires these walls and a sealed door on the interior side of a vestibule to have any insulation value. It would make sense it they were required to have a insulation value to me. Anyone know for sure?

 

[Sifu]

I don't believe they are considered part of the envelope. Certainly I have never considered them that way and have never been concerned about the insulative properties of them. I think if they were considered part of the envelope then there would be no 3,000sf² exception.

 

[JPohling]

The vast majority of vestibules that we see in retail or business uses typically are made from an aluminum and glass storefront system without any significant insulation value. I am unaware of a code requirement for insulation value

 

[Paul Sweet]

Vestibules are mostly to reduce air infiltration when doors are opened, not for additional thermal insulation.

 

[Mr. Inspector]

Just seams odd that a closer is required for the door but the vestibule does not need to be sealed from the interior.

There is no definition or any other requirement in the IECC. So I guess they can have any size openings between the vestibule and the interior of the building as long as the doors have closers..

vestibule​

noun​

ves·ti·bule ˈve-stə-ˌbyül

1
a
: a passage, hall, or room between the outer door and the interior of a building : LOBBY
b
: an enclosed entrance at the end of a railway passenger car
2
: any of various bodily cavities especially when serving as or resembling an entrance to some other cavity or space: such as
a
: the central cavity of the bony labyrinth of the inner ear or the parts (such as the saccule and utricle) of the membranous labyrinth that it contains
b
: the part of the left ventricle below the aortic orifice
c
: the space between the labia minora containing the orifice of the urethra
d
: the part of the mouth cavity outside the teeth and gums
3
: a course that offers access (as to something new)