(A) In addition to the damage prevention requirements of § 154.615, all buildings located in the floodplain shall be protected from flood damage below the flood protection elevation. This building protection requirement applies to the following situations:
(1) Construction or placement of a new building or alteration or addition to an existing building valued at more than $1,000 or 70 square feet;
(2) Substantial improvements or structural alterations made to an existing building that increase the floor area by more than 20% or equal or exceed the market value by 50%. Alteration shall be figured cumulatively over the life of the structure. If substantially improved, the entire structure must meet the flood protection standards of this section;
(3) Repairs made to a substantially damaged building. These repairs shall be figured cumulatively over a ten-year period ending on the date of the last damage event. If substantially damaged, the entire structure must meet the flood protection standards of this section;
(4) Installing a manufactured home on a new site or a new manufactured home on an existing site;
(5) Installing a travel trailer or recreational vehicle on a site for more than 180 days per year;
(6) Damage to a repetitive loss structures as defined in § 154.611;
(7) An exception would be an existing post-FIRM structure may be rebuilt with the first finished floor at greater than one foot above the base flood elevation, provided all of the following conditions are met:
(a) The structure is 100% compliant with all other flood damage prevention provisions of this subchapter prior to the damage event;
(b) The first finished floor is shown to be one foot or more above the base flood elevation by a fully executed elevation certificate;
(c) Said damage is caused by a non-flood event; and
(d) The first finished floor structural members including sheathing and the foundation will require no repairs during reconstruction.
(B) Residential or non-residential buildings can meet the building protection requirements by one of the following methods:
(1) The building may be constructed on permanent land fill in accordance with the following:
(a) The lowest floor (including basement) shall be at or above the flood protection elevation;
(b) The fill shall be placed in layers no greater than six inches before compaction and should extend at least ten feet beyond the foundation before sloping below the flood protection elevation;
(c) The fill shall be protected against erosion and scour during flooding by vegetative cover, riprap, or other structural measure;
(d) The fill shall be composed of rock or soil and not incorporated debris or refuse material; and
(e) Shall not adversely affect the flow of surface drainage from or onto neighboring properties and when necessary stormwater management techniques such as swales or basins shall be incorporated.
(2) The building may be elevated on solid walls in accordance with the following:
(a) The building or improvements shall be elevated on stilts, piles, walls, crawlspace, or other foundation that is permanently open to floodwaters;
(b) The lowest floor and all electrical, heating, ventilating, plumbing, and air conditioning equipment and utility meters shall be located at or above the flood protection elevation. All structural and non-structural materials at or below the flood protection elevation must be flood resistant materials consistent with FEMA standards;
(c) If walls are used, all enclosed areas below the flood protection elevation shall address hydrostatic pressures by allowing the automatic entry and exit of floodwaters. Designs must either be certified by a licensed professional engineer or by having a minimum of one permanent opening on each wall no more than one foot above grade with a minimum of two openings. The openings shall provide a total net area of not less than one square inch for every one square foot of enclosed area subject to flooding below the base flood elevation. If engineered openings are used, a copy of the International Code Council evaluation report is required. This report shall reference the model number of the vents used, specifies the number of vents required for a specific area size located below the BFE, and lists installation requirements; and
(d) The foundation and supporting members shall be anchored, designed, and certified so as to minimize exposure to hydrodynamic forces such as current, waves, ice, and floating debris.
1. All structural components below the flood protection elevation shall be constructed of materials resistant to flood damage.
2. Water and sewer pipes, electrical and telephone lines, submersible pumps, and other service facilities may be located below the flood protection elevation, provided they are waterproofed.
3. The area below the flood protection elevation shall be used solely for parking or building access and not later modified or occupied as habitable space.
4. In lieu of the above criteria, the design methods to comply with these requirements may be certified by a licensed professional engineer or architect.
(e) Enclosed areas below elevated buildings and structures shall comply with the requirements of county codes, shall be limited to parking of vehicles, storage, and building access, and shall comply with the following:
1. Access to the enclosed area shall be the minimum necessary to allow for:
a. Parking of vehicles (garage doors);
b. Limited storage of maintenance equipment used in connection with the premises (one double door set); and
c. Main entrance to the structure.
2. The interior portion of such enclosed area shall not be temperature-controlled by a permanently mounted air-conditioner or connected the HVAC system;
3. No areas are shall be partitioned within the enclosed area, only structural walls are allowed;
4. All construction below the lowest floor shall be built with flood damage-resistant materials consistent with ASCE 24 Flood Resistant Design and Construction;
5. Section 154.614(C) regarding a non-conversion agreement; and
6. The area enclosed below the base flood elevation shall not be used for human habitation. Bathrooms are not allowed.
(3) The building may be constructed with a crawlspace located below the flood protection elevation, provided that the following conditions are met:
(a) The building must be designed and adequately anchored to resist flotation, collapse, and lateral movement of the structure resulting from hydrodynamic and hydrostatic loads, including the effects of buoyancy;
(b) 1. Any enclosed area below the flood protection elevation shall have openings that equalize hydrostatic pressures by allowing for the automatic entry and exit of floodwaters.
2. A minimum of one opening on each wall having a total net area of not less than one square inch per one square foot of enclosed area. The openings shall be no more than one foot above grade. If engineered openings are used, a copy of the International Code Council evaluation report is required. This report shall reference the model number of the vents used, specifies the number of vents required for a specific area size located below the BFE, and lists installation requirements;
(c) The interior grade of the crawlspace below the flood protection elevation must not be more than two feet below the lowest adjacent exterior grade;
(d) The interior height of the crawlspace measured from the interior grade of the crawl to the top of the foundations wall must not exceed four feet at any point;
(e) An adequate drainage system must be installed to remove floodwaters from the interior area of the crawlspace within a reasonable period of time after a flood event;
(f) Portions of the building below the flood protection elevation must be constructed with materials resistant to flood damage; and
(g) Utility systems within the crawlspace must be elevated above the flood protection elevation.
(C) Non-residential buildings may be structurally dry floodproofed (in lieu of elevation) provided a licensed professional engineer or architect certifies that:
(1) Below the flood protection elevation the structure and attendant utility facilities are watertight and capable of resisting the effects of the base flood;
(2) The building design accounts for flood velocities, duration, rate of rise, hydrostatic and hydrodynamic forces, the effects of buoyancy, and the impact from debris and ice;
(3) Floodproofing measures will be incorporated into the building design and operable without human intervention and without an outside source of electricity; and
(4) Levees, berms, floodwalls, and similar works are not considered floodproofing for the purpose of this division (C).
(D) Manufactured homes or travel trailers to be permanently installed on site shall be:
(1) Elevated to or above the flood protection elevation in accordance with division (B) above; and
(2) Anchored to resist flotation, collapse, or lateral movement by being tied down in accordance with the rules and regulations for the State Mobile Home Tie-Down Act issued pursuant to 77 Ill. Adm. Code § 870.
(E) Travel trailers and recreational vehicles on site for more than 180 days per year shall meet the elevation requirements of division (D) above unless the following conditions are met:
(1) The vehicle must be either self-propelled or towable by a light duty truck;
(2) The hitch must remain on the vehicle at all times;
(3) The vehicle must not be attached to external structures such as decks and porches;
(4) The vehicle must be designed and used solely for recreation, camping, travel, or seasonal use, and not as a permanent dwelling;
(5) The vehicle with all area expansions extended must be no larger than 400 square feet;
(6) The vehicle’s wheels must remain on axles and inflated;
(7) Air conditioning units must be permanently attached so as to be safe for movement out of the floodplain;
(8) Propane tanks and electrical and sewage connections must be quick-disconnect and above the 100-year flood elevation;
(9) The vehicle must be licensed and titled as a recreational vehicle or park model; and
(10) The vehicle must either:
(a) Entirely be supported by jacks; or
(b) Have a hitch jack permanently mounted, have the tires touching the ground and be supported by block in a manner that will allow the block to be easily removed by used of the hitch jack.
(F) Garages, sheds, or other minor accessory structures constructed ancillary to an existing residential use may be permitted, provided the following conditions are met:
(1) The garage or shed must be non-habitable;
(2) The garage or shed must be used only for the storage of vehicles and tools and cannot be modified later into another use;
(3) The garage or shed must be located outside of the floodway or have the appropriate state and/or federal permits;
(4) The garage or shed must be on a single-family lot and be accessory to an existing principle structure on the same lot;
(5) Below the base flood elevation, the garage or shed must be built of materials not susceptible to flood damage;
(6) All utilities, plumbing, heating, air conditioning, and electrical must be elevated above the flood protection elevation;
(7) The garage or shed must have at least one permanent opening on each wall not more than one foot above grade with one square inch of opening for every one square foot of floor area. If engineered openings are used, a copy of the International Code Council evaluation report is required. This report shall reference the model number of the vents used, specifies the number of vents required for a specific area size located below the BFE, and lists installation requirements;
(8) The garage or shed must be less than $15,000 in market value or replacement cost whichever is greater or less than 576 square feet;
(9) The structure shall be anchored to resist floatation and overturning;
(10) All flammable or toxic materials (gasoline, paint, insecticides, fertilizers, and the like) shall be stored above the flood protection elevation; and
(11) The lowest floor elevation should be documented and the owner advised of the flood insurance implications.
(Ord. passed 5-16-2023)