Basement or Not?
Scott Fraser
We here recently had an interesting discussion whether the sloping first floor (audience seating) of a local playhouse constituted a "basement."
Theater goers enter the lobby about 1-foot above grade, then enter the theater's rather steep subterranean descent.
My conclusion... it's not a basement, because the main entrance is at the above grade lobby and thus not subterranean on all four side.
Others questioned if entrance level could really be considered at-grade. If not, then it's truly a basement.
What do you think?
Scott
Scott Fraser
FEMA Coordinator/Floodplain Administrator
305-809-3810 o.
305-923-4964 c.
sfr...@keywestcity.com
Rebecca C. Quinn
The definition of “basement” in the building code is slightly different than the definition of the term for floodplain management purposes. Your local flood damage reduction regulations include the NFIP definition. The 2010 FBC, Building – which will have flood provisions - will have two definitions – one specifically or flood hazard areas. It looks like this: BASEMENT. The portion of a building having its floor subgrade (below ground level) on all sides. The definition of “Basement” is limited in application to the provisions of Section 1612 (see “Basement” in Section 502.1).
I think the sloping area you describe is a basement not so much because of the entry/lobby elevation, but because at the bottom of the slope – isn’t there an area that is level – like where the stage is, or the orchestra pit? If yes, then THAT area is below-grade on all sides.
Because this is an existing building (apparently with a very appropriate name!), are you asking the question because of potential substantial improvement? Having to tell an owner that a below-grade area has to be filled in is definitely a tricky situation. Because this is a nonresidential building, an alternative to compliance through elevation (which also includes eliminating below-grade areas) would be to have the building evaluated by a structural engineer to determine if it is feasible to retrofit floodproof. A lot goes into that evaluation, especially for a building with below-grade areas; buoyancy forces associated with saturated ground can pop cause tight, dry-floodproofed buildings to pop out of the ground. I’ve heard of floodproofed buildings that have some form of “pressure relief” mechanism that allows some sand-filtered water inside, to prevent failure of slabs.
Rebecca C. Quinn, CFM
RCQuinn Consulting, Inc.
104 4th St NE #2
Charlottesville VA 22902
434-296-1349 (voice)
443-398-5005 (cell)
320-514-3513 (FAX)
Mike Gambino
If, at the bottom of this structure it is below grade on all sides, it is a basement, in my opinion.
M. Gambino, CFM
Floodplain Administrator
City of Miami Gardens
Public Works Dept.
1050 NW 163 Drive
Miami Gardens, Fl. 33169
Tel. 305.622.8039
Email: mgam...@miamigardens-fl.gov
From: fl_flo...@googlegroups.com [mailto:fl_flo...@googlegroups.com] On Behalf Of Scott Fraser
Sent: Thursday, September 08, 2011 12:14 PM
To: Florida Floodplain Managers Association-List serve
Subject: Basement or Not?
Here's a real-life scenario for you...
Scott Fraser
The question arose when a surveyor had to complete an E/C for the building. It's all academic, as it's a historic structure, but it was an intriguing question.
Yes, there is a leveled area at the bottom of the slope. So this level area then becomes the lowest floor, and thus a basement.
- Yet... what then is the large sloping 'floor' (audience seating area)?
- Is the next highest floor the lobby (discounting for the sake of argument, the stage)?
The next question from the same conversation, involved an enclosed elevator shaft that was a about four feet below the building's main floor (no basement).
- Is the bottom of the shaft considered the lowest floor?
- If the elevator shaft is subterranean on all four sides, is it a basement?
Curious what others think.
Scott
Scott Fraser
FEMA Coordinator/Floodplain Administrator
305-809-3810 o.
305-923-4964 c.
sfr...@keywestcity.com
Mike Gambino
I would say you are correct, also when doing the Elevation Certificate there are instructions on where and how to document basements and elevator shafts. I make anyone doing an elevator sign and seal a Floodproofing Cert at design and as-built, unless the lowest elevation of that shaft is above the BFE, which is unlikely
M. Gambino, CFM
Floodplain Administrator
City of Miami Gardens
Public Works Dept.
1050 NW 163 Drive
Miami Gardens, Fl. 33169
Tel. 305.622.8039
Email: mgam...@miamigardens-fl.gov
