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Church capacity

  • Thread starter Thread starter DwightB
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DwightB

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An architect here, 2006 IBC:

Consider a typical church, which I have in this case. A group of people gather at a time to worship and study. When they study, they are in classrooms throughout the building. When they worship, they are in an assembly room with fixed pews, dutifully seated with one person every 18" (these are really skinny people). There are some occasions when they will also gather for a fellowship dinner. In typical cases, not everyone who comes for worship services will also be there during class time. In fact, during my 39 years of church design, I've seen that most church's have about a 50% to 60% ratio, class to worship proportion. Some churches will average as high as 80% to 90%. We normally see the same pattern with "all church" dinners, in that there are seldom times when everyone will gather for a dinner; the ratio there for many churches is about 50%, but smaller churches actually can approach 100%.

Now comes my current client. We have an assembly space with seating for 239 at 18" per person. I tabulate each pew individually and round down because if a pew does not fit 8.75 people, I only need to count 8 toward room capacity. When those people go to (or come from) classes, this building has 8 classrooms with a total of 111 capacity, or about 46% of worship attendance. When they fellowship, we have a fellowship hall available the seats 244 (7 sf/person), or about 102% capacity.

The building official says the occupant load for this building is 239+111+244=594 and must be sprinkled. Logic would say that the people in worship are the same people who attend those classes and eat those dinners, so the maximum load is the 239 or 244, largest room capacity, both under the 300 capacity sprinkler trigger.

The local zoning regulation for churches requires 1 car per 6 seats, based upon maximum seating capacity. If I use the 244 capacity, then I'm required to provide 41 spaces; I have 60 spaces. If I must use the total number of people with every room filled at once for total occupancy, then using the 1/6 factor, 594 people on site will require 99 cars. If I eliminate the building, I may be able to fit the extra 39 cars, but that would seem to be a Catch-22.
 
Careful with the parking lot justification, because 60 spaces x 6 occupants each = 360 persons, still over the threshold you are trying to stay under.

IMHO it seems reasonable that the sanctuary and fellowship hall may not simultaneously be occupied, but it is challenging to exclude simultaneous occupancy of some or all of the classroom spaces based on my experience attending various churches.

Incidentally, 239 or 244 plus 111 is pretty close to 360!
 
The Code requires worst case scenario of all rooms being occupied at the same time.

The BO is correct
 
The nursery will be the only room used during worship time, so 15 additional at the most, still under 300. The parking lot factor that the city uses here is ridiculous, there won't be 6 people in every car on a Sunday morning; something like 3 people per car is more realistic, so 60 x 3 = 180, which won't even fill the auditorium. Their attendance was as high as 120 after being in existence for about 6 years, now since the tornado, running about 90. Trying to qualify 594 on this site is unreasonable.
 
Visualizing the worst case scenario, how do that many people get there? We aren't allowed on-street parking. Even with a 1/6 car ratio, there is nowhere to put vehicles for 594 people. Also, does that mean that 594 is the number that I'll have to use to calculate toilets also? They were trying to rebuild on an existing slab, using existing plumbing. 300 ladies / 75 will be 4 toilets, we only had two in the pre-tornado structure. (245/2 = 123/75 = 2 toilets)
 
The BO does have the ability to use actual numbers to reduce the OL for design purposes. This is most common in factories but may be used in all occupancies. It is not uncommon for churches and schools to have multiply areas that will not be occupied at the same time. I would be looking at the numbers during Easter and Christmas or other special events to get an actual load versus an average load.

1004.1.1 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 1004.1.1. For areas without fixed seating, the occupant load shall not be less than that number determined by dividing the floor area under consideration by the occupant per unit of area factor assigned to the occupancy as set forth in Table 1004.1.1. Where an intended use is not listed in Table 1004.1.1, the building official shall establish a use based on a listed use that most nearly resembles the intended use.

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 .
 
AegisFPE said:
Careful with the parking lot justification, because 60 spaces x 6 occupants each = 360 persons
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Is there as section in IBC 2006 where building capacity is set according to parking spaces? I'd say no.
 
No , there isn't. And I agree with Mark, the code assumes fully occupied. But, as pointed out, the BO can look at actual numbers, if you can defend them, and give him something to hang his hat on.
 
DwightB said:
An architect here, 2006 IBC: Consider a typical church, which I have in this case. A group of people gather at a time to worship and study. When they study, they are in classrooms throughout the building. When they worship, they are in an assembly room with fixed pews, dutifully seated with one person every 18" (these are really skinny people). There are some occasions when they will also gather for a fellowship dinner. In typical cases, not everyone who comes for worship services will also be there during class time. In fact, during my 39 years of church design, I've seen that most church's have about a 50% to 60% ratio, class to worship proportion. Some churches will average as high as 80% to 90%. We normally see the same pattern with "all church" dinners, in that there are seldom times when everyone will gather for a dinner; the ratio there for many churches is about 50%, but smaller churches actually can approach 100%. Now comes my current client. We have an assembly space with seating for 239 at 18" per person. I tabulate each pew individually and round down because if a pew does not fit 8.75 people, I only need to count 8 toward room capacity. When those people go to (or come from) classes, this building has 8 classrooms with a total of 111 capacity, or about 46% of worship attendance. When they fellowship, we have a fellowship hall available the seats 244 (7 sf/person), or about 102% capacity. The building official says the occupant load for this building is 239+111+244=594 and must be sprinkled. Logic would say that the people in worship are the same people who attend those classes and eat those dinners, so the maximum load is the 239 or 244, largest room capacity, both under the 300 capacity sprinkler trigger. The local zoning regulation for churches requires 1 car per 6 seats, based upon maximum seating capacity. If I use the 244 capacity, then I'm required to provide 41 spaces; I have 60 spaces. If I must use the total number of people with every room filled at once for total occupancy, then using the 1/6 factor, 594 people on site will require 99 cars. If I eliminate the building, I may be able to fit the extra 39 cars, but that would seem to be a Catch-22.
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Sorry, but this is absolutely inexcusable. If you have been designing churches for 29 years using such logic, then you have been doing it wrong for a really long time.

And the code compliant solution is to separate the sanctuary into its own fire area.

v
 
A judjment call is always allowed

such as a school - Classroom 1 student - cafeteria - 1 student at lunch

gym 1 student at recess - library 1 student at reading - auditorium 1 student at assembly

1 student 5 places or 5 places for 1 student

I apply the first for items like plumbing fixtures but each place provides egress

when Boca dissapeared so did non- simultaneous occupancy but it come down to use and occupancy
 
Regarding parking capacity limiting occupancy--many churches around here operate church buses to bring in those who cannot drive and to alliviate inadequate parking lots by shuttling from nearby shopping centers, there are also those who walk and those who bike especially in urban areas.
 
I've never seen a buildings occupant load calculated on how many parking spaces it had. I agree with the bo on this. Assume all rooms occupied. You never know how the building will be used once complete, maybe they have a large and active congregation.

Noah webster wrote the dictionary, daniel webster was a statesmen
 
Assume all rooms occupied
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I agree for egress and sprinklering purposes.

Some mega churches have multiple functions going on at the same time such as 2 morning services and Sunday school classes. The majority do not and to be flexible with plumbing fixtures and parking would not be unrealistic. As for the 1 to 6 parking requirement that is conservative since most cars will not hold that many people.
 
I agree that the IBC does not consider how many parking spaces there are, and some jurisdictions are more sensitive to parking counts than others. I would encourage the OP to consider potential ramifications of their explanation to the local authority to avoid adversely impacting the facility.

For example, if it is presented that really 3 occupants per car is more realistic than 6, then the number of parking spaces that you are telling the jurisdiction they should look for with this project is double what they would normally calculate. With 60 spaces, then you are effectively saying you can only park 180 occupants, and however many more occupants the building holds beyond that will have to find parking elsewhere.

I do not see the authority capping the building occupant load at what you think the parking lot capacity is; rather I see them asking for as much parking as required to support the total occupant load of the facility.

With regard to calculating actual occupant load, this can be challenging for a church because their programming and occupant loads can vary from season to season and year to year.
 
When the congregation grows and on Easter and Christmas (or substitute other high holydays for other traditions) if the congregation does not fit in the pews there will be large screen TVs set up in the social hall or commons for the overflow. Alternatively the worship service will be split with a children's service while the adults study and vice versa. Religious organizations can get real creative in using existing space before the new addition is built. One congregation here put a series of doors at the back of the sanctuary to a patio that is intended to get a tent for overflow twice a year.
 
Frank said:
...intended to get a tent for overflow twice a year.
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Hence the need for proper restrooms and assume full occupancy of the building.

Do they get a permit for the tent?
 
Unfortunately, funeral services can overload a church as well. I attended one for a prison guard's wife. Don't know if there was a BO in the crowd, but I doubt he could have emptied the church with all the police, ambulance crew, and fire fighters present.
 
why is the BO requiring an existing building to be sprinkled?

EDIT:

...both under the 300 capacity sprinkler trigger
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is this a MO requirement?

and is the church use (zoning-wise) grandfathered?
 
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