(A) In addition to the damage prevention requirements of § 151.480, 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 valued at more than $1,000 or 70 square feet;
(2) Substantial improvements made to an existing building. This alteration shall be figured cumulatively beginning with any alteration which has taken place subsequent to the adoption of this subchapter;
(3) Repairs made to a substantially damaged building. These repairs shall be figured cumulatively beginning with any repairs which have taken place subsequent to the adoption of this subchapter;
(4) Structural alterations made to an existing building that increase the floor area by more than 20%;
(5) Installing a manufactured home on a new site or a new manufactured home on an existing site (the building protection requirements do not apply to returning a manufactured home to the same site it lawfully occupied before it was removed to avoid flood damage);
(6) Installing a travel trailer or recreational vehicle on a site for more than 180 days per year; and
(7) Repetitive loss to an existing building as defined in § 151.476.
(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 incorporate debris or refuse materials;
(e) The fill shall not adversely affect the flow of surface drainage from or onto neighboring properties and when necessary, storm water management techniques such as swales or basins shall be incorporated; and
(f) Any fill placed shall be offset by an equal removal of earth from the floodplain to ensure no loss of water storage in the floodplain.
(2) The building may be elevated in accordance with the following:
(a) The building or improvements shall be elevated on stilts, piles, walls or other foundation that is permanently open to flood waters;
(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;
(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 flood waters. Designs must either be certified by a registered professional engineer or by having a minimum of one permanent opening on each wall no more than one foot above grade. 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;
(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;
(e) The finished interior grade shall not be less than the finished exterior grade;
(f) All structural components below the flood protection elevation shall be constructed of materials resistant to flood damage;
(g) 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; and
(h) 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.
(C) Manufactured homes or travel trailers to be permanently installed on site shall be:
(1) Elevated to or above the flood protection elevation; and
(2) Anchored to resist flotation, collapse or lateral movement by being tied down in accordance with the Rules and Regulations for the Illinois Mobile Home Tie-Down Act issued pursuant to 77 Ill. Adm. Code 870.
(D) (1) Travel trailers and recreational vehicles on site for more than 180 days shall meet the elevation requirements of § 151.482 unless the following conditions are met:
(a) The vehicle must be either self-propelled or towable by a light duty truck. The hitch must remain on the vehicle at all times;
(b) The vehicle must not be attached to external structures such as decks and porches;
(c) The vehicle must be designed solely for recreation, camping, travel or seasonal use rather than as a permanent dwelling;
(d) The vehicle's largest horizontal projections must be no larger than 400 square feet;
(e) The vehicle's wheels must remain on axles and inflated;
(f) Air conditioning units must be attached to the frame so as to be safe for movement out of the floodplain;
(g) Propane tanks, electrical and sewage connections must be quick-disconnect and above the 100-year flood elevation; and
(h) The vehicle must be licensed and titled as a recreational vehicle or park model.
(2) The vehicle must be either entirely supported by jacks rather than blocks or have a hitch jack permanently mounted, have the tires touching the ground, and be supported by blocks in a manner that will allow the blocks to be easily removed by use of the hitch jack.
(3) Non-residential buildings may be structurally dry floodproofed (in lieu of elevation) provided a registered professional engineer or architect certifies that:
(a) Below the flood protection elevation the structure and attendant utility facilities are watertight and capable of resisting the effects of the base flood;
(b) 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;
(c) Floodproofing measures will be incorporated into the building design, and operable without human intervention and without an outside source of electricity; and
(d) Compensatory storage has been provided in the floodplain for the building area.
(4) Levees, berms, floodwalls and similar works are not considered floodproofing for the purpose of this division.
(5) Garages or sheds constructed ancillary to a residential use are not permitted.
(6) A building may not be constructed with a crawlspace located below the flood protection elevation.