Lowest floor counts as a story in a required elevated SFR?

[dreamchaser69]

We are building a 3 story (finished) elevated SFR with parking underneath that is located in a V-zone in the panhandle of FL. Elevation requirements vary, but all new coastal construction has to be BFE +3' in our area. The lot is zoned as AE-9 where the house is being placed, however because its within 200' of the sound, it is required to be built to V-zone requirements. We can not enclose, finish or make habitable areas on the lower level. We were told by the local BO that the house would be considered a Threshold Building and therefore subject to inspections, engineering, fire sprinklers and must be built by a CGC as a CBC can not build threshold buildings in FLA. They are saying this is 4 stories. Per the definition of "Threshold Building", we are under the height requirements and use/occupancy does not apply = so we are fighting the determination of number of stories. Therefore - we need to define story and story above grade. We also need to define Floor. Lowest floor is the first finished elevated floor.
Conditions:
House must be elevated 3' above BFE
Parking area underneath can not be enclosed
Concrete slab can not be structural, reinforced, must be frangible and saw cut between the concrete pilings to allow break-away
No footings, grade beams, spread-foundations or other support may be used for the slab
A portion of the parking area can be enclosed as per R322 for elevator/stairs/minimal storage
Design:
The House as designed will have lowest floor approx 14' above the required elevation
First Finished floor is about 11'6" above finished grade.
Parking area underneath will be 2' above the required BFE
Built on concrete pilings / ecospan floor trusses and 4.5 concrete slab = on all finished floor levels
Exterior walls are 12" ICF
The concern here stems from the definition of Grade Plane and Story Above Grade Plane. We know the defined words very well and have found in some codes, this relates specifically to basements but most others have the word basement removed. The "story above grade" plane refers to the average of 4 points where the grade adjoins the "exterior walls" = basement walls, stem wall, etc. Then further by the 6' and 12' rules. In the situation where the home is elevated, the grade does not adjoin the exterior walls as there are none and no supporting footers or grade beams or spread foundations are used. We don't think that this was written or intended for use in houses that have an elevation requirement and therefore could reduce the max 3 story SFR allowance to only be 2 finished floors (2 stories), or could push an existing home into the threshold condition and require sprinklers.

Now for the fun part. After being told this was a threshold building by the local BO, and therefore required to be built under "building code" and not "residential", we started reaching out to other local BO's. We got different answers from almost all of them. Our county said Threshold, the beach agency said 3 story elevated over parking (not threshold), 2 counties east said the same - not threshold as long as it is not enclosed except as allowed for by R322. 1 county to the west said - get this - "if the elevation is over 7' to first finished floor, the lower level is considered a story" (what would someone do with 7' for parking?)

So in the wise kingdom here, is there any work-around to get / determine that the lower level is exempt from being considered a story? (making the assumption that the house is "required" to be elevated and the lower level can not finished)

[Jerry Peck - Codeman]

[dreamchaser69]

Thanks Jerry (Codeman). You definitely know your stuff. I do appreciate all the links and this will be helpful to many that have not researched like I have. All of this is very familiar for me now.

In your answers above, a few things that I did not lay out fully. In your answers you are correct to a degree but some math based on circumstances was off - not your fault.

We are required to build on pilings, no matter what the grade elevation is in regards to the flood-zone. We are in an AE-9 with a driveway /street grade elevation of 11' BFE. We have to go to 12' BFE, so we only need to add a little fill to get the garage floor at or above the required BFE. Last 2 storms that came in ('05 and '06) had a storm surge of 7' more than the current elevation (about 18') - so we are going up to have the lowest beam at or about 22' BFE. So, parking pad is at 12' BFE, grade will be brought in to level it out. We can not enclose that level since we have to build to V-zone standards. We can't use a stem-wall foundation to gain the height, it has to be pilings.

That being said, an option that might have come up is to permit as a S-2 open garage (we meet the the construction type) which is then allowed as a max single story above grade, but not counted in the stories above - so this design because of separation, would be an S-2 open garage under a Group R 3-story.

the other thing we are exploring is FBC-R322.1.5 and how that affects what the lowest floor is and if this excludes the "level" underneath from being considered a floor. No floor - no story.

This does seem to come down to "Story Above Grade" and this is where it gets everyone. When reading the definition, I have found others that specified "basement". That word was removed in the FBC 2017 codes (or sometime before). We think that this was originally intent on being used for foundations like basements, crawl, stem-wall, etc. Where the grade actually touches the exterior of the foundation walls. with the elevated homes, we don't have exterior walls and a piling does not constitute a wall, therefore the definition really should not apply to a piling home.

I think that starting a revolution on this might be in order. So many of the Superstorm Sandy homes have to be elevated and this puts them in the same boat as what I want to build. They have 3 story homes now, have to elevate in some cases another 12' which makes them a Threshold, etc..... I think I will start a effort to have the definition of story above grade modified to accommodate houses that are "required" to be elevated in some form or fashion. Where the story above grade is calculated as the average of the 4 points (typ) around a house on a basement, slab, crawl, etc. If this number is greater than 6' or over 12' anywhere, then its a Story above grade. In the case of elevated piling homes where its required (not by choice), then a sufficient height for parking underneath and enclosure per R322 should be allowed, so maybe the elevated piling house is no more than 12' from finished grade to underside of lowest beam, or unless otherwise specified by the local code if the height requirement is more than 12'. We have a local ord just east of here where the required elevation is 17 feet above current grade........17 feet.

Thanks again - lets see what happens with the S-2 garage under Group R and if I can get any traction with the exclusion of the lowest floor in R322.1.5 from being considered a floor. Then grade starts with my first enclosed level.

[Jerry Peck - Codeman]