The 2021 International Residential Code for One- and Two-Family Dwellings, published by the International Code Council, including Appendix AQ – Tiny Houses, as amended in Chapter 19.20 SGC, is adopted and incorporated by reference with the following specific amendments and modifications:
A. 
Modify Chapter 2 by adding a new definition:
Float home—A single family dwelling unit attached to a flotation device, built to the minimum standards of the IRC and of this ordinance. Float homes are not boats and are subject to all the laws and regulations governing private dwelling units.
B. 
Chapter 4 of the IRC is deleted.
C. 
All references to garages are deleted.
D. 
Stairs providing a required means of egress from an area of not more than 200 square feet shall have a minimum clear width of 30 inches. Maximum riser height shall be not more than eight inches and minimum tread depth shall be not less than nine and one-quarter inches.
E. 
Guards are not required where open decks, balconies, and walkways do not exceed 36 inches in height above the water line.
F. 
Fastenings in areas exposed to the elements shall be hot dipped galvanized steel, marine grade bronze, copper, stainless steel, or other corrosion resistant material suitable for marine use.
G. 
Boat wells under floating structures shall be separated from the dwelling unit, and from structural members supporting the dwelling unit, by a minimum of one layer of five-eighths-inch Type X, water resistant, gypsum wall board, or equivalent approved fire rated assembly. Boat wells shall provide adequate natural ventilation to prevent the buildup of flammable vapors.
H. 
All framing lumber in contact with the flotation device and all framing lumber within 12 inches of the water surface shall be factory preservative treated in accordance with AWPA U1. Plywood shall be exterior grade and all plywood below the deck level shall be marine grade. Any other decay resistant materials shall be approved by the building official.
I. 
Roof coverings shall be fire-resistant or noncombustible.
J. 
The building official shall have the authority to rule on the applicability of this code as it applies to residential floating structures.
(S.G.C. 19.15.010; Ord. 14-23A § 4, 2014; Ord. 18-15 § 4, 2018; Ord. 22-20 § 4, 2022)
A. 
The flotation system shall be designed according to accepted marine engineering and naval architectural principles. The flotation devices shall be structurally sound and securely integrated with the framing for the attached structure. The design shall be approved and sealed by an appropriately licensed professional engineer qualified in such design and shall be submitted to the building official for approval.
B. 
The flotation device shall be watertight, durable and protected from deterioration by water, impact damage due to floating debris, electrolytic action, corrosion, water-borne solvents, organic infestation, chafing or physical abuse. Logs and unprotected plastic foam insulation are not approved flotation devices.
C. 
Where solid flotation devices are not used, hulls shall be fitted with longitudinal and/or transverse watertight bulkheads sufficient to keep the loaded hull afloat with positive stability with any one compartment flooded. No compartment shall compromise more than 20 percent of the total available flotation volume.
D. 
Where solid flotation devices are not used the flotation devices shall be constructed so that access to each compartment is readily available from the first floor level of the completed floating structure.
E. 
A float home with a flotation device other than solid flotation shall be equipped with bilge pumps and a bilge alarm system with detectors in each compartment with audible and visual alarm indicators in the float home. At least one visual indicator shall be located outside the float home in a place visible to passersby.
F. 
The overall buoyancy and stability of the flotation device and attached structure shall be designed to accommodate moving and launching, wave action, loads imposed by mooring, vessels and walkways moored to the structure, live and dead loads, and the design snow loads and wind loads in effect in the city and borough of Sitka.
G. 
The flotation device shall have sufficient stability in both the longitudinal and transverse directions to limit the amount of heel from the horizontal resulting from off-of-center live loading to a maximum of four degrees.
H. 
The flotation system and decking shall provide access to, and protection for, the sewage holding tank.
(S.G.C. 19.15.030; Ord. 14-23A § 4, 2014; Ord. 22-20 § 4, 2022)
The flotation system shall have sufficient buoyancy to support the design weight of the float home plus the maximum combined weight of deadweight items and design snow load and maintain a minimum freeboard of 14 inches. When design wind load is applied to the superstructure the amount of heel shall be not more than four degrees from horizontal or one-half the freeboard, whichever is less. Freeboard is measured from the surface of the water to the bottom of the lowest floor or deck framing members.
(S.G.C. 19.15.040; Ord. 14-23A § 4, 2014; Ord. 22-20 § 4, 2022)
In addition to the requirements of the IRC, including but not limited to Chapter 3, Section R311, floating homes shall have a 24-inch minimum width open deck on all sides. Decks shall be constructed so as to prevent the ponding of water.
(S.G.C. 19.15.050; Ord. 14-23A § 4, 2014; Ord. 22-20 § 4, 2022)
Cleats, bollards, bull rails or other such devices shall be sufficient in number and attached to the floating structure in such a way as to provide adequate mooring points to secure the float home in the highest design wind load. Mooring lines shall be kept in good condition, kept free of chafing, and shall be removable without the use of tools.
(S.G.C. 19.15.060; Ord. 14-23A § 4, 2014; Ord. 22-20 § 4, 2022)
A. 
Where floating homes are provided with a clear space of at least eight feet between adjacent structures measured from building wall line horizontal to adjacent building wall line and roof eave projections are no closer than six feet, Tables 302.1(1) and (2) of the IRC shall not apply.
B. 
Where floating homes are placed closer than eight feet from building wall line horizontal to building wall line, walls, eaves and roofs shall be constructed in accordance with Tables 302.1(1) and (2) of the IRC.
C. 
A clear space of four feet shall be provided between adjacent floats.
(S.G.C. 19.15.070; Ord. 14-23A § 4, 2014; Ord. 22-20 § 4, 2022)