• Welcome to The Building Code Forum

    Your premier resource for building code knowledge.

    This forum remains free to the public thanks to the generous support of our Sawhorse Members and Corporate Sponsors. Their contributions help keep this community thriving and accessible.

    Want enhanced access to expert discussions and exclusive features? Learn more about the benefits here.

    Ready to upgrade? Log in and upgrade now.

Elevated SFR in HVHZ (V-Zone) lowest level counts as a story?

D

Dreamchaser

REGISTERED
Joined
Apr 23, 2018
Messages
19
Location
Gulf Breeze, FL
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 construction has to be BFE +3'. 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 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. 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 or story above grade. We also need to define Floor. Lowest floor is the first finished elevated floor.
Conditions:
  1. House must be elevated 3' above BFE
  2. Parking area underneath can not be enclosed
  3. Concrete slab can not be structural, reinforced, must be frangible and saw cut between the concrete pilings to allow break-away
  4. No footings, grade beams, spread-foundations or other support may be used for the slab
  5. A portion of the area can be enclosed as per R322 for elevator/stairs/minimal storage
Design:
  1. The House as designed will have lowest floor approx 14' above the required elevation
  2. First Finished floor is about 11'6" above finished grade.
  3. Parking area underneath will be 2' above the required BFE
  4. Built on concrete pilings / ecospan floor trusses and 4.5 concrete slab = on all finished floor levels
  5. 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 the lower level exempt from being considered a story? (making the assumption that the house is "required" to be elevated and not finished)

We found a possible work-around and would like your comments. We think we could permit the parking area under 510.4 as an S-2 Garage (meeting the fire codes of course) which then precludes the lower level from being considered a story for classification / type of construction - which then means this a 3 story SFR over an S-2 (separate building) and not a 4 story. Again, the height is not a concern as FL allows 50' above finished grade as a max height before it becomes and threshold building.
510.4 Parking beneath Group R.
Where a maximum one-story above grade plane Group S-2 parking garage, enclosed or open, or combination thereof, of Type I construction or open of Type IV construction, with grade entrance, is provided under a building of Group R, the number of stories to be used in determining the minimum type of construction shall be measured from the floor above such a parking area. The number of stories to be used in determining the height in stories in accordance with Section 903.2.11.3 shall include the parking garage as a story. The floor assembly between the parking garage and the Group R above shall comply with the type of construction required for the parking garage and shall also provide a fire-resistance rating not less than the mixed occupancy separation required in Section 508.4.
 
Unless fla uses IBC for houses S-1 does not apply

IRC should

What are other houses doing in your area for new build, with your questions???
 
I used to work for a firm that designed large houses (the inspector called them "mini-hotels") on the coast. We sometimes used heavy timber construction to get the equivalent of a fire rating so we didn't have to go to VA construction. This was before the IBC required sprinklers in all residences.
 
FBC adopted all their codes from the IBC. However, certain things changed in the FBC like the exclusion of SFR's from having fire suppression.

The home as designed is essentially a 3-hour rated building except for the main stairwell (1-hour), however there is exterior egress on all floors to grade. Concrete floors and steel beam trusses, concrete exterior walls, fire-rated ceilings, tile floors throughout = basically the only thing that can burn is the furniture. Bullet-proof to a degree.

That being said, this seems to be a "first" that is actually being argued. Most folks change their dreams and designs when told this is 4 stories and therefore a threshold building that has the additional requirements = and in our case, this means about $45K - $55K in additional cost. It's all about the determination of the lowest level being considered a story. Which under normal circumstances could be classified as a story if not being built in a V-Zone. If this were an X zone, then we could build the 4 story, finish the lower level and occupy that level. In this instance, we can not. Not habitable, not structural, not enclosed.
FBC has S-1 and S-2 classifications.

As I mentioned, its really coming down to the BO (building official). 3 agencies said this is a 3 story elevated over a parking area. 1 county has a limit of 7' before considering a story. Our county said its a 4 story building, even though we can't finish the lower level. The reference here really comes from "story above grade plane" and that it was likely intended for basements, crawlspace, stem-wall designs. Not intended for a flood zone requirement (emphasized) that the house be elevated. One neighboring area has a requirement that the house be elevated to 17' above grade.

FBC allows a SFR to be 4 stories max. However, it also states that any building 4 stories or more is a Threshold Building.

Ironically, per R322.1.5, the lowest floor is defined as the lowest enclosed floor and excludes any level that has a limited flood-proof enclosure for access/elevator and the level is used solely for parking/storage. However, the county we are in still counts this as a floor = therefore a story.

The question here is: How and when can the lower level be excluded from being considered a floor or a story.
 
If you have private conversation rights

Write a message to Jar546 , he is I think the only one on the board in Florida.

He may know the answer
 
Dreamchaser said:
CDA - found it! Thanks, sent message.
Click to expand...


Click on the head top right

Click on the envelope looking thing top of that page

Than hit start conversation

You might have to be a paid member to do it
Only 35 and helps support the self supporting site
 
Sounds to me the house is mostly outside the prescriptive of the IRC and would need to be built under the IBC anyway. JMHO. The AHJ is the one you need to convince or appeal the interpretation.
 
Jut found some interesting stuff in a binding determination in FL that might help in my case. I just posted on the forum about construction type classification. Depending on what you guys say there - I might just be in the money.
 
Dreamchaser said:
Jut found some interesting stuff in a binding determination in FL that might help in my case. I just posted on the forum about construction type classification. Depending on what you guys say there - I might just be in the money.
Click to expand...



Sometimes I recommend hire a code consultant

The money spent can sometimes save money!!

Especially since you are dealing with Fla laws and conditions.
 
You must log in or register to reply here.
Back
Top