Interpretation #8598
Published January 11, 2022
Original Request
- Code Version
- 2021
- Code
- RESIDENT
- Code Description
- Chapter
- Section
- R322.3.5
- Topic
- Walls below design flood elevation
Question
Is it the intent of the FBC, R Sections R322.3.2, R322.3.3 and R322.3.5 to not allow a residential building to use shear walls for structural support even though there is a provision in FBC,B Section 3109.3.2.2? Is the intent that residential buildings in Coastal A and V Zones are only allowed to have breakaway walls below the required FEMA and/or FDEP (CCCL) flood elevation?
Answer Published 01/11/2022 at 6:26 PM
The State Floodplain Office has provided the following information related to the FBC Residential and FBC Building:
• R301.2.5 requires structures seaward of the CCCL to be designed in accordance with Sec 3109 of FBCB. The inquiry does not cite this section.
• R322.1.11 has the same, and goes on to state “the more restrictive provisions shall govern.” The inquiry doesn’t cite this section.
• R322.2 doesn’t limit the type of foundation in Zone A/AE (other than CAZ), with the implication that shear walls are permitted (as are perimeter walls and elevation on fill).
• R322.3.3 allows only pilings and columns in Zone V (not shear walls) and in Coastal A Zone (where Limit of Moderate Wave Action is delineated or the community adopts it’s on map/definition), piling, columns, and backfilled stem walls are permitted (not shear walls, perimeter walls, or fill).
• 3109 is recognized as “more applicable” to commercial/large buildings. On the surface, it permits shear walls subject to the limitations outlined in 3109.3.2 (specifically 3109.3.2.2).
• So the answer depends on the flood zone designated on the Flood Insurance Rate Map (and LiMWA):
o If the site is in Zone X, then the flood provisions of the FBC do not apply and shear walls can be used
o If the site is in Zone A/AE other than CAZ, then shear walls can be used
o If the site is in Zone V/CAZ, then the limitations of R322.3 prevail because R322.1.11 says “the more restrictive provisions shall govern,” and that means shear walls cannot be used
• Please also refer to the BASF Fact Sheet on CCCL Requirements and narrative for Sec. 3109.3.2.2, download here www.floridadisaster.org/dem/mitigation/floodplain/community-resources (look under FBC Resources).
• R301.2.5 requires structures seaward of the CCCL to be designed in accordance with Sec 3109 of FBCB. The inquiry does not cite this section.
• R322.1.11 has the same, and goes on to state “the more restrictive provisions shall govern.” The inquiry doesn’t cite this section.
• R322.2 doesn’t limit the type of foundation in Zone A/AE (other than CAZ), with the implication that shear walls are permitted (as are perimeter walls and elevation on fill).
• R322.3.3 allows only pilings and columns in Zone V (not shear walls) and in Coastal A Zone (where Limit of Moderate Wave Action is delineated or the community adopts it’s on map/definition), piling, columns, and backfilled stem walls are permitted (not shear walls, perimeter walls, or fill).
• 3109 is recognized as “more applicable” to commercial/large buildings. On the surface, it permits shear walls subject to the limitations outlined in 3109.3.2 (specifically 3109.3.2.2).
• So the answer depends on the flood zone designated on the Flood Insurance Rate Map (and LiMWA):
o If the site is in Zone X, then the flood provisions of the FBC do not apply and shear walls can be used
o If the site is in Zone A/AE other than CAZ, then shear walls can be used
o If the site is in Zone V/CAZ, then the limitations of R322.3 prevail because R322.1.11 says “the more restrictive provisions shall govern,” and that means shear walls cannot be used
• Please also refer to the BASF Fact Sheet on CCCL Requirements and narrative for Sec. 3109.3.2.2, download here www.floridadisaster.org/dem/mitigation/floodplain/community-resources (look under FBC Resources).
Commentary
None.