I have seen instances where an egress path down the middle, or around the perimeter of a room classified as 'tables and chairs' was deducted from the gross area to obtain the net area, therefore reducing the occupant load. Has anyone else used this approach? Is it valid?
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Calculating Net Area
- Thread starter Phil B
- Start date
That's what I thought, but I've seen it done.
Tim Mailloux
Registered User
very flaky and not consistent with the IBC definition
[BE] FLOOR AREA, NET. The actual occupied area not including unoccupied accessory areas such as corridors, stairways, ramps, toilet rooms, mechanical rooms and closets.
Commentary
This area is intended to include only the room areas that are used for specific occupancy purposes and does not include circulation areas, such as corridors, ramps or stairways, or service and utility spaces such as toilet rooms and mechanical and electrical equipment rooms. Net floor area is typically measured between inside faces of walls within a room. Floor area, net and gross, is utilized in Table 1004.5 to determine occupant load for a space.
[BE] FLOOR AREA, NET. The actual occupied area not including unoccupied accessory areas such as corridors, stairways, ramps, toilet rooms, mechanical rooms and closets.
Commentary
This area is intended to include only the room areas that are used for specific occupancy purposes and does not include circulation areas, such as corridors, ramps or stairways, or service and utility spaces such as toilet rooms and mechanical and electrical equipment rooms. Net floor area is typically measured between inside faces of walls within a room. Floor area, net and gross, is utilized in Table 1004.5 to determine occupant load for a space.
steveray
SAWHORSE
If the room is net, you can take out those areas (within reason).....Unless I am misunderstanding...?
Commentary
This area is intended to include only the room areas that are used for specific occupancy purposes and does not include circulation areas,
Other wise do you do the circulation path as 15 or 5?
If you cut it that close and then change something and egress no longer works or you need a sprinkler system, then I would say not to design to the absolute limit....
Commentary
This area is intended to include only the room areas that are used for specific occupancy purposes and does not include circulation areas,
Other wise do you do the circulation path as 15 or 5?
If you cut it that close and then change something and egress no longer works or you need a sprinkler system, then I would say not to design to the absolute limit....
Not a sprinkler issue. Less seats = less parking. I am just looking for opinions because I agree that the verbiage re: circulation areas could be interpreted as not being part of the net area of a space.
Having said that, I also firmly agree about not designing to the absolute limits.
steveray
SAWHORSE
This should prove interesting...But may be slow on a Friday....
Paul Sweet
Sawhorse
The occupant load factors (square feet per occupant) already include an allowance for circulation aisles.
Yep, I have heard that also, and that's the more prudent approach.
mtlogcabin
SAWHORSE
No you do not take those areas out the aisles and such are already factored into the net area
1004.5 Areas without fixed seating.
The number of occupants shall be computed at the rate of one occupant per unit of area as prescribed in Table 1004.5. For areas without fixed seating, the occupant load shall be not less than that number determined by dividing the floor area under consideration by the occupant load factor assigned to the function of the space as set forth in Table 1004.5.
Look at the OL Table for assemblies and they are net. Then go to 1029 and you will find code requirements for the aisles within the net floor area.
A circulation path is interior or exterior when you are moving from on area to another
Tim Mailloux
Registered User
you cut off the commentary a bit too soon... does not include circulation areas, such as corridors, ramps or stairways, or service and utility spaces such as toilet rooms and mechanical and electrical equipment rooms.
that doesnt mean you can carve out circulation areas inside a conferenceroom of classroom and not include them in the occupant load calculation for the space.
bill1952
SAWHORSE
As a 33+ year member of NFPA Assembly Occupancies Technical Committee, this:
And so it shall be! Thanks to all for comments and opinions.
steveray
SAWHORSE
So......When you have a wide open restaurant with a bar...Where do you stop the 15 or 7 or 5 OL factor......? Or do you do the whole place at 5 because the bar could spill out through the whole place and there could be people standing in the egress paths?
Hence my "within reason"....I'm just saying that there is some gray in there
Hence my "within reason"....I'm just saying that there is some gray in there
But it doesn't mean you can't....And it is only commentary.....
steveray
SAWHORSE
We are still allowed to think and use some common sense as to an area that is likely to be occupied for a particular use or not......Also why we post and assign occupant loads....Do we include hallways as they are not mentioned....?
mtlogcabin
SAWHORSE
1001.1 General.
Buildings or portions thereof shall be provided with a means of egress system as required by this chapter. The provisions of this chapter shall control the design, construction and arrangement of means of egress components required to provide an approved means of egress from structures and portions thereof.
1004.1 Design occupant load.
In determining means of egress requirements, the number of occupants for whom means of egress facilities are provided shall be determined in accordance with this section.
1004.3 Multiple function occupant load.
Where an area under consideration contains multiple functions having different occupant load factors, the design occupant load for such area shall be based on the floor area of each function calculated independently.
1004.5 Areas without fixed seating.
The number of occupants shall be computed at the rate of one occupant per unit of area as prescribed in Table 1004.5. For areas without fixed seating, the occupant load shall be not less than that number determined by dividing the floor area under consideration by the occupant load factor assigned to the function of the space as set forth in Table 1004.5. Where an intended function is not listed in Table 1004.5, the building official shall establish a function based on a listed function that most nearly resembles the intended function.
Exception: Where approved by the building official, the actual number of occupants for whom each occupied space, floor or building is designed, although less than those determined by calculation, shall be permitted to be used in the determination of the design occupant load.
IMHO
Design the means of egress for the highest OL possible for the use. If you want to post a smaller OL for some other reason, parking, pay per view, plumbing fixture count, then that is up to the AHJ
bill1952
SAWHORSE
As a designer, I show my opinion on a drawing, try to review with users/owners, and it goes into the set presumably looked at in plan review for permit.
steveray
SAWHORSE
Exactly.....Do you count 2 people for the 5x5ish area for door approach? I am not saying discount all of the walking areas between the tables or anything drastic, but a reasonable area for a general circulation path I would accept...This is why there was a 2024 code change submitted for elevator lobbies because of a lack of reasonableness on what the OL should be...
bill1952
SAWHORSE
I probably do include door landings. Admittedly most of these are theatre style seating - stack chairs and some portable risers. The ballroom dining layouts have been to justify and obtain permission for greater ol and posting than the square footage factors.