Forum ProfileBack
Advanced

— Forum Scope —




— Match —





— Forum Options —





Minimum search word length is 3 characters - maximum search word length is 84 characters

Lost password?
sp_TopicIcon
Calculating Occupant Loads
June 5, 2008
8:24 am
Avatar
pdove
Member
Members
Forum Posts: 1464
Member Since:
April 9, 2008
sp_UserOfflineSmall Offline

Rjj:

I like your concept, however I do not deduct or subtract the bathrooms since the occupancy of these rooms is normal to the occupancy of the area being calculated. With regards to your figure, be careful to divide the total square footage by the occupant load factor in your code (I believe it?s a typo in your posting). Your figure is close but exceeds permitted OL by (63 Persons) using the following example.

Since it?s the morning and I?m getting ready to draw up some Pre Incident Plans, I felt like a little math:

Problem:
120? by 100? Drinking Establishment = 12,000 s.f. (Net Criteria)
1? by 50? Partition Wall = 50 s.f.
30? by 15? Lobby Area = 450 s.f.
20? by 6? Bar = 120 s.f.
24? by 16? Dance Floor = 384 s.f.

Total Area = 12,000 ? 1004 = 10,996 s.f.
Occupant Load Factor = (1 per 15)
10,996 / 15 = 733 Total Occupancy

Using your figure: 12000 / 15 = 800
800 ? 4 = 796 (Exceeds permitted by 63)

Note: There are some who may interpret the Lobby for a waiting space at (1 per 3 or 5) which increases the total OL but the official''s interpretation as to being more restrictive for Assemblies is the norm in my experiences.

However codes permit increase in OL if egress capacity is sufficient which is always a consideration the official has open or in some cases strongly opposes depending on situations and attitudes. Weekend approaches and the gills are bedding, time to take out the #2 and fly fish them off the beds????it?s a blast!

June 4, 2008
12:57 pm
Avatar
pdove
Member
Members
Forum Posts: 1464
Member Since:
April 9, 2008
sp_UserOfflineSmall Offline

Here''s another outlook for what it''s worth that I use when I teach new inspectors about occupant loads: ..........Yea I know it''s from the other code body but it helps them understand the concepts.

Net Floor Area. The floor area within the inside perimeter of the outside walls, or the outside walls and fire walls of the building under consideration with deductions for hallways, stairs, closets, thickness of interior walls, columns, or other features.

Other features = any fixed assembly where people would not occupy the physical space being used by the fixed assembly. (Bar, counters, gaming fixtures etc.)

There are specific calculations for areas for gaming ?Casinos and Similar Gaming Areas? and it?s 11 gross which is the same as ICC''s.

September 25, 2007
2:05 pm
Avatar
maniac
Member
Members
Forum Posts: 5194
Member Since:
March 7, 2001
sp_UserOfflineSmall Offline

Without fixed there are no distinct aisles, with no distinct aisles, you cannot deduct them.

There is nothing in the code that allows a deduction for aisles

2006 INTERNATIONAL BUILDING CODE COMMENTARY
The net floor area permits the exclusion of certain spaces that would be included in the gross floor area.
The net floor area is intended to apply to the actual occupied floor areas. The area used for permanent building components, such as shafts, fixed equipment, thicknesses of walls, corridors, stairways, toilet rooms, mechanical rooms and closets, is not included in net floor area. For example, consider a restaurant dining area with dimensions measured from the inside of the enclosing walls of 80 feet by 60 feet (24 384 mm by 18 288 mm) (see Figure 1004.1.1). Within the restaurant area is a 6-inch (152 mm) privacy wall running the length of the room [80 feet by 0.5 feet = 40 square feet (3.7 m2)], a fireplace [40 square feet (3.7 m2)] and a cloak room [60 square feet (5.6 m2)]. Each of these areas is deducted from the restaurant area, resulting in a net floor area of 4,660 square feet (433 m2). Since the restaurant intends to have unconcentrated seating that involves loose tables and chairs, the resulting occupant load is 311 persons (4,660 divided by 15). As the definition of ?Floor area, net? indicates, certain spaces are to be excluded from the gross floor area to derive the net floor area. The key point in this definition is that the net floor area is to include the actual occupied area and does not include spaces uncharacteristic of that occupancy.
Group A-2 occupancies could have low lighting levels, loud music, late hours of operation, dense seating with ill-defined aisles and alcoholic beverage service. These factors in combination could delay fire recognition, confuse occupant response and increase egress time.
2006 INTERNATIONAL BUILDING CODE COMMENTARY

June 5, 2008
1:47 pm
Avatar
jim baird
Member
Members
Forum Posts: 1546
Member Since:
December 8, 2000
sp_UserOfflineSmall Offline

They don''t let me in places like that except to inspect.

The last time I ate their, they asked me to leave because I was using my pocket fishermen on neighboring tables for the catch of the day. I protested to no avail! Even though the sign said all you can eat.

June 5, 2008
1:20 pm
Avatar
cda
Member
Members
Forum Posts: 5641
Member Since:
July 16, 2000
sp_UserOfflineSmall Offline

rjj
It did not take me much gas and I got all the fish I wanted at this water hole:

http://www.longjohnsilvers.com/

June 5, 2008
12:55 pm
Avatar
pdove
Member
Members
Forum Posts: 1464
Member Since:
April 9, 2008
sp_UserOfflineSmall Offline

Big LOL....almost fell out of chair!

June 5, 2008
12:49 pm
Avatar
rj2085
Member
Members
Forum Posts: 2491
Member Since:
January 24, 2008
sp_UserOfflineSmall Offline

Math is Good! And yes, you took the bait and all my line. I Was about to tag the end before I cut you loose with a few occupants just so I could find you when you tired.

Gas is slowing me up. Last months bill was a shock. In fact, I only fished sat. morning because of gas issues.

Coho! yes! a few months off!

June 5, 2008
12:09 pm
Avatar
pdove
Member
Members
Forum Posts: 1464
Member Since:
April 9, 2008
sp_UserOfflineSmall Offline

rjj:

Insert finger into corner of mouth and pull back slightly, took the bait and ran off about 600 yards 😉 How''s my math!

Big eyes, muskie and pike too. Can''t get out to the big lakes for Kings and Coho due to fuel costs pulling the Lund but might go out tonight after that great one and filet and release 😀

June 5, 2008
8:52 am
Avatar
rj2085
Member
Members
Forum Posts: 2491
Member Since:
January 24, 2008
sp_UserOfflineSmall Offline

Pdove: It is Thursday! I was pulling your leg! 🙂

I here you have lakes in Michigan? walleyes? Bass? Muskies???

June 5, 2008
8:24 am
Avatar
pdove
Member
Members
Forum Posts: 1464
Member Since:
April 9, 2008
sp_UserOfflineSmall Offline
sp_Print Print Post Post #10

Rjj:

I like your concept, however I do not deduct or subtract the bathrooms since the occupancy of these rooms is normal to the occupancy of the area being calculated. With regards to your figure, be careful to divide the total square footage by the occupant load factor in your code (I believe it?s a typo in your posting). Your figure is close but exceeds permitted OL by (63 Persons) using the following example.

Since it?s the morning and I?m getting ready to draw up some Pre Incident Plans, I felt like a little math:

Problem:
120? by 100? Drinking Establishment = 12,000 s.f. (Net Criteria)
1? by 50? Partition Wall = 50 s.f.
30? by 15? Lobby Area = 450 s.f.
20? by 6? Bar = 120 s.f.
24? by 16? Dance Floor = 384 s.f.

Total Area = 12,000 ? 1004 = 10,996 s.f.
Occupant Load Factor = (1 per 15)
10,996 / 15 = 733 Total Occupancy

Using your figure: 12000 / 15 = 800
800 ? 4 = 796 (Exceeds permitted by 63)

Note: There are some who may interpret the Lobby for a waiting space at (1 per 3 or 5) which increases the total OL but the official''s interpretation as to being more restrictive for Assemblies is the norm in my experiences.

However codes permit increase in OL if egress capacity is sufficient which is always a consideration the official has open or in some cases strongly opposes depending on situations and attitudes. Weekend approaches and the gills are bedding, time to take out the #2 and fly fish them off the beds????it?s a blast!

June 4, 2008
1:47 pm
Avatar
rj2085
Member
Members
Forum Posts: 2491
Member Since:
January 24, 2008
sp_UserOfflineSmall Offline
sp_Print Print Post Post #11

Pdove: please check my figures!

Net Floor Area= - theOSW - fire walls - hallways - stairways - closets - thickness of walls - columns - bath rooms - any other feature you can think of = X x oc per sf = oc load.

Most of the time if I take the total sf and x oc per sf = oc - 4 I am with in 1.

June 4, 2008
12:57 pm
Avatar
pdove
Member
Members
Forum Posts: 1464
Member Since:
April 9, 2008
sp_UserOfflineSmall Offline
sp_Print Print Post Post #12

Here''s another outlook for what it''s worth that I use when I teach new inspectors about occupant loads: ..........Yea I know it''s from the other code body but it helps them understand the concepts.

Net Floor Area. The floor area within the inside perimeter of the outside walls, or the outside walls and fire walls of the building under consideration with deductions for hallways, stairs, closets, thickness of interior walls, columns, or other features.

Other features = any fixed assembly where people would not occupy the physical space being used by the fixed assembly. (Bar, counters, gaming fixtures etc.)

There are specific calculations for areas for gaming ?Casinos and Similar Gaming Areas? and it?s 11 gross which is the same as ICC''s.

June 3, 2008
11:25 am
Avatar
cda
Member
Members
Forum Posts: 5641
Member Since:
July 16, 2000
sp_UserOfflineSmall Offline
sp_Print Print Post Post #13

Sorry it is broke up

You have to look at each area/ room and fiqure occupant load,

also look at table 1004.1.2 to see when you apply net and gross, that is why I say you have to calulate each use of the room/heating-oil-tank-hot-exam-oregon rea

FLOOR AREA, GROSS. The floor area within the in side per -
im e ter of the ex te rior walls of the build ing un der con sid er ation,
exclusive of vent shafts and courts, with out de duc tion for cor ri -
dors, stair ways, clos ets, the thick ness of in te rior walls, col -
umns or other fea tures. The floor area of a build ing, or por tion
thereof, not pro vided with sur round ing ex te rior walls shall be
the us able area un der the hor i zon tal pro jec tion of the roof or
floor above. The gross floor area shall not in clude shafts with
no open ings or in terior courts.
FLOOR AREA, NET. The ac tual oc cupied area not in cluding
un oc cu pied ac ces sory ar eas such as cor ridors, stair ways, toi let
rooms, me chan i cal rooms and clos ets.

June 3, 2008
11:12 am
Avatar
arizonapm
Member
Members
Forum Posts: 9
Member Since:
June 3, 2008
sp_UserOfflineSmall Offline
sp_Print Print Post Post #14

Im working on my first project where I have multiple uses and I am trying to determine the difference between Net and Gross calculation. If I am reading this correctly I would take the total square footage of the building and then subtract any of the net square footage out of that. So if I have a 10,000 sf bldg that is R-1 and inside I have 3 rooms that are 3,000 total unconcentrated assembly my calculation would be 7,000/200 and 3,000/Construction exceeding the minimum requirements5 giving me a total load of 235. Can someone please let me know if I am doing this calculations correctly. Also do I only count the open floor area in the assembly spaces, meaning I dont count the area of the fixed chairs?

October 24, 2007
7:52 pm
Avatar
builder bob
Member
Members
Forum Posts: 408
Member Since:
May 12, 2004
sp_UserOfflineSmall Offline
sp_Print Print Post Post #15

I think I covered that aspect with the original post... while the occupant load calculatioins may have been off base for the game room areas........the concept still required the means of egress to be designed for the occupant load without the pool tables...... [QUOTE]Pool tables could be construed as game rooms.....50 net. I would not be to hung up on it if the designer proposed the means of egress to meet the more stringent requirement of 15 net or 7 net....and calculated the occupant load for the pol tables at 50 net.

[/QUOTE]

October 24, 2007
5:51 pm
Avatar
inspector131
Member
Members
Forum Posts: 424
Member Since:
October 28, 2006
sp_UserOfflineSmall Offline
sp_Print Print Post Post #16

Thanks, gvictor, you summarized it nicely.

I don''t know about you, BuilderBob, but I''ve been in a bar or two in my day where the crowd easily overwhelmed the ability to shoot pool on a busy night.

IMHO, the objective of doing occupancy calculations is to make a good faith estimate of the maximum [i]plausible[/i] occupancy of a space consistent with overall use -- not necessarily the maximum [i]ideal[/i] occupancy of that space.

Using the 50 sq-ft/person gross factor might very well give you a good idea of how many people would be [i]ideal[/i] around a pool table in use but it fails miserably as an estimation of how many people will inevitably fill that space in the real world on a night when the bar is busy.

(BTW, if you want to actually draw out a pool table and space around it, you want 5'' clear on all sides of the table. In practice in most places, however, it''s not as if nobody who isn''t actively playing pool ever stands in that space. Frequently that space overlaps other uses including the next pool table''s space, aisle space, and general standing room. People just get out of the way when someone needs to shoot from that part of the table.)

October 24, 2007
12:54 pm
Avatar
gvictor
Member
Members
Forum Posts: 194
Member Since:
July 9, 2000
sp_UserOfflineSmall Offline
sp_Print Print Post Post #17

The average size pool table in a bar is worth about 2-2 1/2 people @ 15, not really a huge impact. Just forget the pool table and count the whole area. A pool hall would be a different matter, but in a bar they may take it away, or move it around to facilitate other issues. The important thing is to get enough exits and exit width so that when they remove the table exiting will still be adequate.

October 24, 2007
11:28 am
Avatar
builder bob
Member
Members
Forum Posts: 408
Member Since:
May 12, 2004
sp_UserOfflineSmall Offline
sp_Print Print Post Post #18

Inspect.... have you actually drawn out a floor plan with pool table......and figured out the occupant load? 15 net is way to restrictive, and at that occupant load, you couldn''t shoot pool without wacking somebody with a pool cue (usually around 0200 hrs it seems on friday night).

BE sure to read the part about [b]when the could be becomes reality, then it could be construed as a change of use.....and be made to come up to current code.[/b]

October 24, 2007
6:30 am
Avatar
inspector131
Member
Members
Forum Posts: 424
Member Since:
October 28, 2006
sp_UserOfflineSmall Offline
sp_Print Print Post Post #19

IMHO, using "exercise room" for a pool table is a stretch. I''ve had nothing but trouble with architects trying to use the exercise room load factor improperly to keep occupancy numbers artificially low when the unconcentrated assembly is really a better fit for the proposed use of the space...

IMHO, both ICC and NFPA need to supply objective definitions for that one in their next editions. (Thanks for reminding me that I wanted to submit a proposal on that... 🙂 )

October 24, 2007
5:36 am
Avatar
builder bob
Member
Members
Forum Posts: 408
Member Since:
May 12, 2004
sp_UserOfflineSmall Offline
sp_Print Print Post Post #20

Sorry...Inspect 131 was trying to go from memory...and it has been a long day...Thanks for keeping me straight.

Anyhow variables to consider:

Exercise rooms 50 gross or

Assembly
Gaming floors (keno, slots, etc.) 11 gross

I believe that I would be comfortable using exercise rooms for the pool table area. Limited the space for calculations to 3 feet from edge of tables. The remainder of the space would be standing room until you hit the table and chair areas, dance floors would have another occupant load calculations, etc., etc., etc.

I still stand by the concept of the original post.....ensure the means of egress are more (based upon 15 net) but don''t fret about property. This is another case of as is and not could be....when the could be becomes reality, then it could be construed as a change of use.....and be made to come up to current code.