Mezzanine Question

[AaronA]

I am only allowed two stories but have 26' total height to play with and am thinking about incorporating a mezzanine into our design. Am I allowed to build underneath the mezzanine. I would like to put a closet and bathroom under the mezzanine. Would that be allowed?

 

[mtlogcabin]

Yes just remember your ceiling height requirements

505.2 Mezzanines.
A mezzanine or mezzanines in compliance with Section 505.2 shall be considered a portion of the story below. Such mezzanines shall not contribute to either the building area or number of stories as regulated by Section 503.1. The area of the mezzanine shall be included in determining the fire area. The clear height above and below the mezzanine floor construction shall be not less than 7 feet (2134 mm).

 

[walker.t]

505.2 Mezzanines.

505.2 is an IBC provision, the original poster started the thread in the Residential Building Codes forum.

Yes just remember your ceiling height requirements

I don’t know the limits for openness under the IRC before a mezzanine is considered a story. For some reason I can’t access the ICC site to view the IRC to find provisions regarding interior space dimensions. The original poster lists California as their location, are there any special requirements in the California code for mezzanines and stories?

 

[mtlogcabin]

It is the same in the IRC
2018 IRC
SECTION R325
MEZZANINES

R325.1 General.
Mezzanines shall comply with Sections R325 through R325.5. Habitable attics shall comply with Section R325.6.

R325.2 Mezzanines.
The clear height above and below mezzanine floor construction shall be not less than 7 feet (2134 mm).

R325.3 Area limitation.
The aggregate area of a mezzanine or mezzanines shall be not greater than one-third of the floor area of the room or space in which they are located. The enclosed portion of a room shall not be included in a determination of the floor area of the room in which the mezzanine is located.

Exception: The aggregate area of a mezzanine located within a dwelling unit equipped with a fire sprinkler system in accordance with Section P2904 shall not be greater than one-half of the floor area of the room, provided that the mezzanine meets all of the following requirements:

1. Except for enclosed closets and bathrooms, the mezzanine is open to the room in which such mezzanine is located.

2. The opening to the room is unobstructed except for walls not more than 42 inches (1067 mm) in height, columns and posts.

3. The exceptions to Section R325.5 are not applied.

R325.4 Means of egress.
The means of egress for mezzanines shall comply with the applicable provisions of Section R311.

R325.5 Openness.
Mezzanines shall be open and unobstructed to the room in which they are located except for walls not more than 36 inches (914 mm) in height, columns and posts.

Exceptions:

1. Mezzanines or portions thereof are not required to be open to the room in which they are located, provided that the aggregate floor area of the enclosed space is not greater than 10 percent of the mezzanine area.

2. In buildings that are not more than two stories above grade plane and equipped throughout with an automatic sprinkler system in accordance with Section R313, a mezzanine shall not be required to be open to the room in which the mezzanine is located.