Gross Floor Area

[rockwellmusic]

We have a local fire inspector who is trying to claim that our design for an unconditioned, unfinished basement with a <7.5' headspace is an increase in the habitable square footage. Along with the increase upstairs, this is triggering a $20,000 fire sprinkler retrofit which will kill our budget and prevent the project from being built.

Definitions of "gross floor area" that I can find on the internet say that ceilings less than 7.5' do not count as gross floor area. He wants to see the basement roof less than 7 feet, which would probably be OK for our plans to use the space for storage, but would impact resale value. Is there a definition in the California Building Code for "gross floor area" that I can use to appeal this decision about our building plans?

 

[cda]

Welcome

Give it a few days for great answers

Do you have a link to the section requireing fire sprinklers, so we can see the wording.

 

[cda]

If this is the CRC you are looking at,,,, Does not appear there is one

Chapter 2: Definitions, California Residential Code 2019 | UpCodes

UpCodes offers a consolidated resource of construction and building code grouped by jurisdiction

up.codes

 

[cda]

And unless local or state fire marshal requirement:::


R313.2 One- And Two-Family Dwellings Automatic Fire Sprinkler Systems


An automatic residential fire sprinkler system shall be installed in one- and two-family dwellings.

1. An automatic residential fire sprinkler system shall not be required for additions or alterations to existing buildings that are not already provided with an automatic residential sprinkler system.
2. Accessory Dwelling Unit, provided that all of the following are met:
   1. The unit meets the definition of an Accessory Dwelling Unit as defined in the Government Code Section 65852.2.
   2. The existing primary residence does not have automatic fire sprinklers.
   3. The accessory detached dwelling unit does not exceed 1,200 square feet in size.
   4. The unit is on the same lot as the primary residence.

 

[cda]

this is from CBC

FLOOR AREA, GROSS. The floor area within the inside perimeter of the exterior walls of the building under consideration, exclusive of vent shafts and courts, without deduction for corridors, stairways, ramps, closets, the thickness of interior walls, columns or other features. The floor area of a building, or portion thereof, not provided with surrounding exterior walls shall be the usable area under the horizontal projection of the roof or floor above. The gross floor area shall not include shafts with no openings or interior courts.

 

[mark handler]

And unless local or state fire marshal requirement:::


R313.2 One- And Two-Family Dwellings Automatic Fire Sprinkler Systems


An automatic residential fire sprinkler system shall be installed in one- and two-family dwellings.

1. An automatic residential fire sprinkler system shall not be required for additions or alterations to existing buildings that are not already provided with an automatic residential sprinkler system.
2. Accessory Dwelling Unit, provided that all of the following are met:
   1. The unit meets the definition of an Accessory Dwelling Unit as defined in the Government Code Section 65852.2.
   2. The existing primary residence does not have automatic fire sprinklers.
   3. The accessory detached dwelling unit does not exceed 1,200 square feet in size.
   4. The unit is on the same lot as the primary residence.

Per usual, we do not have the whole story.

Many municipalities, with high fire areas, have amended the fire codes, as example:
Chapter 15.12 - OAKLAND FIRE CODE
Amend: 903.2.11.1 Stories without openings. An automatic sprinkler system shall be installed throughout every story or basement without openings.

 

[classicT]

The fact that you are calling it a basement leads me towards agreeing with the FM.

Even if unfinished, you will probably be using it as a storage room, hobby space, etc. Items placed down in the "basement" will supply a fire with fuel, which must be mitigated by a fire sprinkler system.

If it were a crawl space, I would agree.... but an unfinished basement, put the sprinklers in.

 

[Paul Sweet]

The unamended IBC 903.2.11.1 requires sprinklers in stories (including basements) over 1500 SF where there are fewer openings than required farther on in that paragraph. It looks like Oakland just amended out the 1500 SF exemption.

 

[Mr. Inspector]

Add some extra lumber to the basement ceiling to bring the ceiling height down below 6' 8" or add a beam below 6'-4" and call it a crawl space.