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Calculating "fire area" for commercial retail strip

patriot07

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Joined
Apr 15, 2025
Messages
3
Location
Dallas TX
I have been told that modern commercial code requires a fire suppression system if the building has over 5,000 square feet of "fire area". I am not a code expert. We are building a structure that is 4,982 square feet measured from the outside of exterior framing. It's a little over 5,000 square feet if the lowered brick ledge outside of the exterior framing is included in the calculation (and even more if you calculate under roof since the roof extends past the walls a bit. Best I can find online, the "fire area" is actually calculated from the sheet rock (aka fire barrier) on the inside of the exterior framing. Can someone help clarify what square footage is used to calculate "fire area" in relation to the requirement for a fire suppression system?
 
The limitations on fire areas for fire sprinkler installation vary depending on the type of occupancy. Since you mentioned commercial retail, I am assuming you have a Group M (for mercantile) occupancy. A Group M occupancy has a maximum fire area of 12,000 sq. ft. before a sprinkler system is required, so you are well under that threshold.

However, to answer your question about how floor area is measured, it is the area within the exterior walls. Thus, you do not include the area occupied by exterior walls or roof overhangs (i.e., eaves) unless the overhang is an extension of the roof or floor above and typically covers usable space.
 
A Group M occupancy has a maximum fire area of 12,000 sq. ft. before a sprinkler system is required,
Unless you are doing upholstered furniture or mattresses which is much lower....So that is a watchout....

And you would possibly be precluded from any true A2s as the threshold is 100 OL and I believe is 5000 sqft, but that is fire area, which is typically inside the walls:
When in doubt, go to the definitions:

[BF]FIRE AREA. The aggregate floor area enclosed and bounded by fire walls, fire barriers, exterior walls or horizontal assemblies of a building. Areas of the building not provided with surrounding walls shall be included in the fire area if such areas are included within the horizontal projection of the roof or floor next above.

And Welcome to THE Forum!
 
The limitations on fire areas for fire sprinkler installation vary depending on the type of occupancy. Since you mentioned commercial retail, I am assuming you have a Group M (for mercantile) occupancy. A Group M occupancy has a maximum fire area of 12,000 sq. ft. before a sprinkler system is required, so you are well under that threshold.

However, to answer your question about how floor area is measured, it is the area within the exterior walls. Thus, you do not include the area occupied by exterior walls or roof overhangs (i.e., eaves) unless the overhang is an extension of the roof or floor above and typically covers usable space.
Thanks!

I don't know what the occupancy rating is. I just know it's zoned C-2 for commercial usage. Sorry...

But thanks for the reply!
 
Unless you are doing upholstered furniture or mattresses which is much lower....So that is a watchout....

And you would possibly be precluded from any true A2s as the threshold is 100 OL and I believe is 5000 sqft, but that is fire area, which is typically inside the walls:
When in doubt, go to the definitions:

[BF]FIRE AREA. The aggregate floor area enclosed and bounded by fire walls, fire barriers, exterior walls or horizontal assemblies of a building. Areas of the building not provided with surrounding walls shall be included in the fire area if such areas are included within the horizontal projection of the roof or floor next above.

And Welcome to THE Forum!
Thanks!

No upholstered furniture or mattresses for sure. Looking at possibly a salon and spa.

What code specifically is that excerpt from?

Really appreciate your help.
 
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