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City of Cranston
City of Cranston Zoning Ordinance
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§ 17.16.100

Specific standards

  • A. Construction Standards for A-Zones.
    • 1. Residential Construction.
      • a. New construction, substantial improvements or repair to substantially damaged structures shall have the bottom of the lowest floor including basement and utilities elevated to or above the BFE or the elevation required by the Rhode Island Building Code (whichever is greater).
      • b. Should solid foundation perimeter walls be used to elevate a structure, the structure shall comply with the standards specified in Section 17.16.100(A)(4).
      • c. Prior to the issuance of any CO, certification shall be provided as required by Section 17.16.110(A).
    • 2. Non-Residential Construction.
      • a. New construction, substantial improvements or repair to substantially damaged structures shall:
        • i. Have the bottom of the lowest floor including basement and utilities elevated to or above the BFE or the elevation required by the Rhode Island Building Code (whichever is greater); or
        • ii. Have the bottom of the lowest floor including basement and utilities dry floodproofed to or above the BFE or the elevation required by the Rhode Island Building Code (whichever is greater) with watertight walls that are substantially impermeable to the passage of water, and constructed with structural components having the capability of resisting hydrostatic and hydrodynamic loads and the effects of buoyancy. Floodproofing measures shall take into account flood velocities, duration, and rate of rise, hydrostatic pressures, and impacts from debris or ice and shall be operable without human intervention and without an outside source of electricity.
      • b. Prior to the issuance of any CO, certification shall be provided as required by Section 17.16.110(B).
    • 3. Manufactured (Mobile) Homes and Recreational Vehicles (RVs).
      • a. New manufactured homes, substantial improvements or repair to substantially damaged manufactured homes shall have the bottom of the lowest floor including utilities elevated to or above the BFE or the elevation required by the Rhode Island Building Code (whichever is greater).
      • b. Manufactured homes shall be securely anchored on a permanent foundation which itself is securely anchored so to resist flotation, lateral movement and hydrostatic pressures. Anchoring may include, but not be limited to, the use of over-the-top or frame ties to ground anchors.
      • c. Manufactured homes shall be installed using methods and practices which minimize flood damage.
      • d. Public utilities for manufactured homes or subdivisions shall be constructed so as to minimize flood damage.
      • e. Prior to the issuance of any CO, certification shall be provided as required by Section 17.16.110(A).
      • f. Recreational vehicles placed on site shall be on the site for fewer than one hundred eighty (180) consecutive days.
    • 4. Elevated Structures. New construction, substantial improvements, or repair to substantially damaged structures that include fully enclosed areas formed by a foundation and other exterior walls below the BFE or the elevation required by the Rhode Island Building Code (whichever is greater) of an elevated structure, shall be designed to allow for the entry and exit of flood waters to automatically equalize hydrostatic flood forces on exterior walls. Designs showing compliance with this section shall be certified by a RPE or registered architect prior to the issuance of any building permit and shall meet the following standards:
      • a. The enclosed area shall be less than three hundred (300) square feet.
      • b. The enclosed area shall be used only for the parking of vehicles, building access or storage of maintenance equipment used in connection with the premises.
      • c. Access to the enclosed area shall be the minimum necessary to allow for the parking of vehicles (garage door) or storage of maintenance equipment used in connection with the premises (standard exterior door) or entry to the living area (stairway or elevator).
      • d. The enclosed area shall not be used as living space (human habitation) or partitioned into separate rooms.
      • e. There shall be a minimum of two openings (hydraulic flood vents) having a total net area of not less than one square inch for every one square foot of enclosed area subject to flooding. These hydraulic openings shall be located on at least two different walls. Only the area that lies below the BFE shall be used in the calculation of net area of vents required.
      • f. The bottom of all openings shall be no higher than one foot above grade. At least one side of the structure's enclosed area shall be at or above grade. Fill placed around the foundation walls shall be graded so that the elevation inside the enclosed area is equal to or higher than the adjacent outside elevation on at least one side of the structure. The foundation slab of a residential structure, including the slab of a crawlspace, shall be set equal to the outside finished grade on at least one side of the structure.
      • g. Openings may be equipped with screens, louvers, valves or other coverings or devices provided they permit the automatic passage of flood waters without any external influence or control such as human intervention or the use of electrical or other non-automatic mechanical means. Other coverings may be designed and certified by a PE and approved by the BI.
      • h. Walls, floor, and ceiling materials located below the BFE or the elevation required by the Rhode Island Building Code (whichever is greater) shall be unfinished and be constructed of flood resistant materials.
      • i. Utilities, washers, dryers, and food freezers shall be elevated to or above the BFE or the elevation required by the Rhode Island Building Code (whichever is greater).
      • j. For structures constructed with a crawl space:
        • i. The interior height of the crawlspace measured from the interior grade of the crawl to the top of the foundation wall shall not exceed four feet at any point.
        • ii. An adequate drainage system shall be installed to remove floodwaters from the interior area of the crawlspace within a reasonable period of time after a flood event.
      • k. A copy of the legally recorded deed restriction prohibiting the conversion of the area below the lowest floor to a use or dimension contrary to the structure's originally approved design shall be provided to the city's floodplain manager prior to the issuance of any CO.
    • 5. Critical Facilities.
      • a. Construction of new critical facilities shall be prohibited within the five hundred (500) year floodplain.
      • b. Substantial improvements or repair to substantially damaged critical facilities shall:
        • i. Have the bottom of the lowest floor, including basement and utilities either elevated or dry floodproofed to or above the five hundred (500) year flood plus two feet of freeboard, as required by Section 17.16.100(A)(2)(a).;
        • ii. Provide access to said facility that is elevated to or above the five hundred (500) year flood plus two feet of freeboard;
        • iii. Have toxic substances stored on site floodproofed and sealed to ensure that said substances shall not be displaced by or released into floodwaters.
      • c. Prior to the issuance of any CO, certification shall be provided as required by Section 17.16.110(B).
    • 6. Accessory Structures.
      • a. All accessory structures shall:
        • i. Not be used for human habitation. An apartment, office or other finished space over an accessory structure is considered human habitation and shall require the structure to be elevated to or above the BFE or the elevation required by the Rhode Island Building Code (whichever is greater).
        • ii. Be used only for the storage of vehicles and/or limited storage and shall not be modified into another use.
        • iii. Be built of flood resistant materials below the BFE or the elevation required by the Rhode Island Building Code (whichever is greater).
        • iv. Have all utilities elevated to or above the BFE or the elevation required by the Rhode Island Building Code (whichever is greater).
        • v. Have all flammable or toxic materials stored above the BFE or the elevation required by the Rhode Island Building Code (whichever is greater).
      • b. Attached Garages.
        • i. A garage attached to a structure shall have the garage floor slab elevated to or above the BFE or the elevation required by the Rhode Island Building Code (whichever is greater) or be dry floodproofed to above the BFE or the elevation required by the Rhode Island Building Code (whichever is greater).
      • c. Detached garages and accessory structures shall:
        • i. Have unfinished interiors.
        • ii. Be wet floodproofed to above the BFE or the elevation required by the Rhode Island Building Code (whichever is greater).
        • iii. Be no more than five hundred (500) square feet.
        • iv. Be anchored to resist floatation, collapse, lateral movement and overturning.
    • 7. Foundation Protection. A structure may be constructed on permanent fill in accordance with the following standards:
      • a. Fill shall be placed in layers no greater than one foot deep before compacting.
      • b. The top of the fill shall be no lower than the BFE or the elevation required by the Rhode Island Building Code (whichever is greater) and extend a minimum of ten (10) feet beyond the foundation of the structure before sloping below the BFE or the elevation required by the Rhode Island Building Code (whichever is greater). The ten (10) feet minimum may be waived if a RPE certifies an alternative method has been provided to protect the structure from damage due to erosion, scour, and other hydrodynamic forces.
      • c. Fill used to support structures shall be compacted to ninety-five (95) percent of the maximum density obtainable by the Standard Proctor Test (ASTM Standard D-698) and its suitability to support structures shall be certified by a RPE.
      • d. Fill shall be protected against erosion and scour during flooding. Slopes shall be no greater than two to one horizontal/vertical. Flatter slopes may be required where velocities may cause erosion.
      • e. The fill shall not adversely affect the flow or surface drainage from or onto abutting properties.
    • 8. Standards for Shallow Flooding Zones. Located in the SFHAs are areas designated as shallow flooding areas which have flood hazards associated with BFE of one foot to three feet, where a clearly defined channel does not exist and the water path of flooding is unpredictable and indeterminate; in said areas the following requirements shall apply:
      • a. Residential Construction.
        • i. New construction, substantial improvements, and repairs to substantially damaged structures shall have the lowest floor including basement and utilities elevated three feet higher than the flood depth number specified on the FIRM above the highest adjacent grade. If no flood depth is specified, the lowest floor including basement and utilities shall be elevated no less than three feet above the highest adjacent grade.
        • ii. Adequate drainage paths around structures on slopes shall be provided to guide floodwaters around and away from proposed structures.
        • iii. Prior to the issuance of any CO, certification shall be provided as required by Section 17.16.110(A).
      • b. Non-Residential Construction. New construction, substantial improvements, and repair to substantially damaged structures shall:
        • i. Have the lowest floor, including basement and utilities elevated three feet higher than the flood depth number specified on the FIRM above the highest adjacent grade. If no flood depth is specified, the lowest floor, including basement, shall be elevated no less than three feet above the highest adjacent grade; or
        • ii. Have the bottom of the lowest floor, including basement and utilities dry floodproofed to an elevation three feet higher than the flood depth number specified on the FIRM above the highest adjacent grade with watertight walls that are substantially impermeable to the passage of water, and shall be constructed with structural components having the capability of resisting hydrostatic and hydrodynamic loads and the effects of buoyancy. Floodproofing measures shall take into account flood velocities, duration, and rate of rise, hydrostatic pressures, and impacts from debris or ice and shall be operable without human intervention and without an outside source of electricity. If no flood depth is specified, the floodproofing elevation shall be elevated no less than three feet above the highest adjacent grade.
        • iii. Adequate drainage paths around structures on slopes shall be provided to guide floodwaters around and away from proposed structures.
        • iv. Prior to the issuance of any CO, certification shall be provided as required by Section 17.16.110(B).
      • c. Manufactured (Mobile) Homes and Recreational Vehicles (RVs).
        • i. New manufactured homes, substantial improvements and repair to substantially damaged structures shall have the lowest floor including basement and utilities elevated three feet higher than the flood depth number specified on the FIRM above the highest adjacent grade. If no flood depth is specified, the lowest floor including basement and utilities shall be elevated no less than three feet above the highest adjacent grade.
        • ii. All manufactured homes shall be securely anchored on a permanent foundation which itself is securely anchored so to resist flotation, lateral movement and hydrostatic pressures. Anchoring may include, but not be limited to, the use of over-the-top or frame ties to ground anchors.
        • iii. All manufactured homes shall be installed using methods and practices which minimize flood damage.
        • iv. Public utilities and facilities in manufactured homes or subdivisions shall be constructed so as to minimize flood damage.
        • v. Prior to the issuance of any CO, certification shall be provided as required by Section 17.16.110(A).
        • vi. Recreational vehicles placed on sites shall be on the site for fewer than one hundred eighty (180) consecutive days.
  • B. Construction Standards in V-Zones and Coastal A-zones.
    • 1. Residential and Non-Residential Construction. New and substantial improvements, and repair to substantially damaged structures:
      • a. Shall be elevated and secured to anchored pilings or columns and shall have the bottom of the lowest horizontal structural member of the structure and utilities elevated to or above the BFE or the elevation required by the Rhode Island Building Code (whichever is greater).
      • b. The pile or column foundation and structure attached thereto shall be anchored to resist flotation, collapse, and lateral movement due to the effects of wind and water loads acting simultaneously on all building components. Water loading values used shall be those associated with the base flood. Wind loading values used shall be those required by applicable state building codes.
      • c. Shall be certified by a RPE or registered architect that the design and methods of construction meet elevation and anchoring requirements.
      • d. Shall have space below the lowest floor either free of obstruction or constructed with breakaway walls. Any enclosed space shall be used solely of building, building access, or storage and shall not be used for human habitation.
      • e. Shall not utilize fill for structural support.
      • f. New development shall be located on the landward side of the reach of mean high tide.
      • g. Prior to the issuance of any CO, certification shall be provided as required by Section 17.16.110(A).
    • 2. Manufactured Homes.
      • a. The placement of new manufactured homes shall not be permitted.
      • b. Existing manufactured homes which are substantially improved or repaired because they have sustained substantial damage:
        • i. Shall be elevated and secured to anchored pilings or columns and shall have the bottom of the lowest horizontal structural member of the structure and utilities elevated to or above the BFE or the elevation required by the Rhode Island Building Code (whichever is greater).
        • ii. The pile or column foundation and structure attached thereto shall be anchored to resist flotation, collapse, and lateral movement due to the effects of wind and water loads acting simultaneously on all building components. Water loading values used shall be those associated with the base flood. Wind loading values used shall be those required by applicable state building codes.
        • iii. Shall be certified by a RPE or registered architect that the design and methods of construction meet elevation and anchoring requirements.
        • iv. Shall have space below the lowest floor either free of obstruction or constructed with breakaway walls. Any enclosed space shall be used solely for building access or storage and shall not be used for human habitation.
        • v. Shall not utilize fill for structural support.
    • 3. Recreational vehicles placed on sites shall be on the site for fewer than one hundred eighty (180) consecutive days.

(Ord. 2013-27, § 1, 8/26/2013; Ord. 2015-28, § 1, 8/24/2015)