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R-2 Rooftop Patio and Number of Stories

RLGA

RLGA

SAWHORSE
Staff member
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Oct 18, 2009
Messages
3,536
Location
Phoenix, AZ
2009 IBC applies.

I'm looking at a 4-story, R-2 condominium building. The architect has provided a rather large rooftop patio that could easily handle up to 500 occupants using a 7 sf/occ. factor for assembly use.

My concern is this, since the architect has identified this as a Type VA building, sprinklered throughout with a NFPA 13 system, the allowable height and area, including increases for both, complies with Chapter 5. However, the rooftop patio is easily be classified as a Group A-3. Table 503 limits Group A-3 to 2 stories (3 stories with sprinkler increase), but since this rooftop patio is technically not a story by definition (no roof above), then is this acceptable?

I know means of egress need to comply with Chapter 10 per Section 1004.8.

Thanks!
 
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At 1st glance I would say no because the A-3 is above the 3rd floor

2009 IBC

506.5.2 More than one story above grade plane.

For buildings with more than one story above grade plane and containing mixed occupancies, each story shall individually comply with the applicable requirements of Section 508.1. For buildings with more than three stories above grade plane , the total building area shall be such that the aggregate sum of the ratios of the actual area of each story divided by the allowable area of such stories based on the applicable provisions of Section 508.1 shall not exceed 3.

Some may argue the roof is not a story and I agree however the A-3 use is limited to a maximum height of 3 stories in the building you described.

Don't forget

1607.11.2.2 Special-purpose roofs.

Roofs used for promenade purposes, roof gardens, assembly purposes or other special purposes, and marquees, shall be designed for a minimum live load, Lo, as specified in Table 1607.1. Such live loads are permitted to be reduced in accordance with Section 1607.9. Live loads of 100 psf (4.79 kN/m2) or more at areas of roofs classified as Group A occupancies shall not be reduced.
 
I kind of agree, but I'm getting hung up on the "story" term. The rooftop patio is not a story by IBC definition, so technically, the A-3 is not within a story.

I know I'm splitting hairs, but architects, in defense of their designs, tend to split hairs and I'd like something pretty solid to back me up.
 
The roof (A-3) would have to be separated from the Group R below as required by Table 508.3.3 (1 hour) and the height of the roof would need to be less than permitted by Table 503, with modifications. The roof is not a story.
 
By definition, 2009 IBC, Chapter 2, Definitions, Story, the A-3 roof patio is not a story. I am also in agreement with Coug Dad, although it appears difficult to find that 'shall be' section of code stable enough to stand on.

I would also add that this seems to be in line with the intention of 509.2 for horizontal building separation allowances in the Special Provisions Section. Obviously, your project does not meet those requirements as you do not meet the type of construction requirements and the occupant load maximums (unless separated to areas with < 300 occs) required to put a Group A occupancy on the top floor.
 
It's acceptable being that occupiable roofs are not a story and if not a fire area; to restrict occupant load except for means of egress. 504.3; an A-3 is not what I would consider as habitable occupancy by definition.
 
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IMHO

The occupancy A-3 can not be above the thrid level (story).

Regardless of the definition of a story

The options as I see it are to change the area sq footage of the deck

or to change the type of construction.
 
I would look at the Floor of the pation / garden / being occupied as 5 floor, roof or not, it is the location of the space being occupied. So would it be a type 1 construction? maybe it's clear as mud.

code sction 1004.8 seems to suggest that such areas, spaces, occupancies would only have to comply with egress, (1004.8 Outdoor areas > because no roof ???? hard sell here)

So if as a space related to the R-2 use only; I may consider it as only the egress. (chilling)

In reality the enforcement of such a restriction of use would be next to impossible to regulate

If a multile occupancy like in 1004.9 I would consider it as a mixed use and then 503 height and area would be a Type 1 building.
 
The key is occupancy not stories.

The number of stories and height for the fire area containing the A3 occupancy is measured from grade 508.3.3.3 for separated occupancies.

Of course, unseparated would never comply either.

The plans bearing the architect's seal should be sent to the State Board regulating the profession for investigation.
 
brudgers said:
The key is occupancy not stories.The number of stories and height for the fire area containing the A3 occupancy is measured from grade 508.3.3.3 for separated occupancies.

Of course, unseparated would never comply either.

The plans bearing the architect's seal should be sent to the State Board regulating the profession for investigation.
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It's not a fire area without a roof.......I don't like it, but I have had that fight and gotten beaten soundly on it....on this board in fact....not saying that RLGA's DP is correct, but A3 fire area can not be considered a reason for denial...
 
FIRE AREA. The aggregate floor area enclosed and bounded by firewalls, fire barriers, exterior walls or fire-resistance-rated horizontal assemblies of a building.

No enclosure, no walls, no barriers....just blue sky and sunshine.........Sunshine!
 
AREA, BUILDING. The area included within surrounding exterior walls (or exterior walls and firewalls) exclusive of vent shafts and courts. Areas of the building not provided with surrounding walls shall be included in the building area if such areas are included within the horizontal projection of the roof or floor above.

Doesn't count for BA either.....just egress for occupant load.....Again...I don't like it, but it is what it is....for now...
 
I have seen a lot of sun decks allowed over the years on the roofs of apartment, condo, and office buildings above the story where a Group A occupancy would otherwise be allowed. The issues have always been the rating of the roof and providing an elevator for accessibility.
 
I am questioning why a rooftop patio is being assumed to be an A occupancy. Did the architect designate it as such?

And Coug Dad, Steveray and others are right; this isn't a story, nor is it a fire area. If it were a fire area, it would have to have fire suppression. Do they provide rooftop sprinklers in Alabama?
 
steveray said:
FIRE AREA. The aggregate floor area enclosed and bounded by firewalls, fire barriers, exterior walls or fire-resistance-rated horizontal assemblies of a building.No enclosure, no walls, no barriers....just blue sky and sunshine.........Sunshine!
Click to expand...
Directions:

1. Read the definition of "floor area" ["net" for assembly occupancies].

2. Recognize that there is a difference between floor area and building area.

3. Note that the exterior walls will bound the roof terrace.

4. Hang head in shame.
 
texasbo said:
I am questioning why a rooftop patio is being assumed to be an A occupancy. Did the architect designate it as such? And Coug Dad, Steveray and others are right; this isn't a story, nor is it a fire area. If it were a fire area, it would have to have fire suppression. Do they provide rooftop sprinklers in Alabama?
Click to expand...
If over 300 occupants any A1-A4 occupancy would require sprinklers per the IBC throughout the floor area see 903.2.1

Note also that 903.2 applies to buildings and structures.

Fortunately the State Fire Marshal's office is not staffed with Building Officials/Zoning Officials from Texas.
 
SO....IF THE FLOOR SYSTEM IS CANTILEVERED IT DOES NOT COUNT? Sorry about the caps...stupid MUNIS needs them...not yelling...Net and gross are used for MOE calcs....notice gross says "within exterior walls" also

If there is an exterior stair, the exterior walls will also not "bind" you...but alot of cheese might...

If occupied space is the trigger, (floor area net) we need to sprinkler every out door dining area in the country....

Thanks for the debate Brudgers, but I do not want to take this any more OT than we already are....I would like to lean more your way on this subject, but the word ENCLOSED keeps getting in the way...
 
steveray said:
but the word ENCLOSED keeps getting in the way...
Click to expand...
Unfortunately, he has selective reading comprehension. Any detail that obstructs the outcome he desires, he simply dismisses.

And why not use a term that is specifically referring to egress, if it makes your case regarding building height?

903 requires buildings with Group A "floor areas" to be fire sprinklered. "Floor area" is clearly defined by "inside perimeter walls", and if no exterior walls, then "under the horizontal projection of the roof above". "Story" is clearly defined by between two floors or a floor and a roof. You may pretend to see exterior walls and/or roof in your fantasies, but they just don't exist.

So this space is not a story, nor part of the building area, floor area (except for exiting), nor fire area. Sorry brudgers, you don't get to sprinkler the roof, and there is nothing in the code that says the occupied roof is a story, nor that it is too high. And all you have to do is look at every single building that's built like this across the country to know that you are wrong.

I know it's hard to visualize these things when you're living in the backwoods; just leave it to those of us who have actually been out in the big world and aren't intimidated by anything larger than a tobacco shed.
 
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brudgers said:
The key is occupancy not stories.
Click to expand...
texasbo said:
I am questioning why a rooftop patio is being assumed to be an A occupancy. Did the architect designate it as such?
Click to expand...
The roof is above the 4th story above grade; A-3 use group cannot be more than 3 stories above grade with NFPA 13.

We have apartments and recreation centers with lap pools on the roof and it works out part of main use group per 303.1.
 
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