Rules for building a residential safe room in Hawaii

Section 429 of the International Building Code is amended by adding section 429 to read as follows: SECTION 429 HAWAII RESIDENTIAL SAFE ROOM 429.1 Performance-based design criteria. The residential safe room shall meet the minimum performance specifications of sections 429.1.1 through 429.10. 429.1.1 Intent and scope. The intent of the residential safe room is to temporarily provide an enhanced protection area, fully enclosed within a dwelling or within an accessory structure to a residence, which is designed and constructed to withstand the wind pressures, windborne debris impacts, and other requirements of this section. 429.1.2 Alternative standards. 1. Manufactured safe room designs subject to approval. A manufactured safe room or safe room kit may be substituted if documentation is submitted and approved by the building official. The safe room shall be engineered, tested, and manufactured to meet or exceed the criteria of this section. 2. FEMA in-residence shelter designs permitted. It shall be permissible to build FEMA In-Residence Shelters of up to 64 square feet of floor area with walls up to 8 feet long that are built in accordance with construction details of FEMA 320. 429.2 Site criteria. Residential safe rooms shall not be constructed within areas subject to stream flooding, coastal flooding or dam failure inundation within any of the following areas: 1. FEMA Special Flood Hazard Areas (SFHA) subject to rainfall runoff flooding or stream or flash flooding; 2. Coastal zones "V" or "A" identified in the Flood Insurance Rate Map (FIRM) issued by FEMA for floodplain management purposes, in which the flood hazard are tides, storm surge, waves, tsunamis, or a combination of these hazards; 3. Areas subject to dam failure inundation as determined by the Department of Land and Natural Resources. 429.3 Size of safe room. The safe room shall be designed to provide a minimum of 15 square feet per person in a room which does not need to exceed 120 square feet (11 m 2 ) of floor area. 429.4 Provisions for exiting. The safe room shall be equipped with an inward-swinging interior door and an impact- protected operable window or exterior door suitable for a means of alternative exiting in an emergency. 429.5 Design for dead, live, wind, rain, and impact loads. 429.5.1 Structural integrity criteria. 1. The residential safe room shall be built with a complete structural system and a complete load path for vertical and lateral loads caused by gravity and wind. 2. The building that the residential safe room is in shall be assumed to be destroyed by the storm and shall not be taken as offering any protective shielding to the safe room enclosure. 3. The ceiling structure and wall shall be capable of supporting a superimposed debris load of the full weight of any building floors and roof above, but not less than 125 psf. 4. The residential safe room enclosure shall be capable of simultaneously resisting lateral and uplift wind pressures corresponding to a 145 mph 3-second peak gust ultimate design wind speed, determined in accordance with ASCE 7, Minimum Design Loads for Buildings and Other Structures. The site exposure factor shall be based on exposure C or the exposure shown in Figure 1609.4, whichever is the greater. The values for the gust factor and the directionality factor shall be taken as 0.85. Topographic wind amplification caused by mountainous terrain shall be considered in accordance with the building code. Internal pressure shall be determined in accordance with ASCE 7. 5. The residential safe room shall be anchored to a foundation system capable of resisting the above loading conditions. 429.5.2 Windborne debris impact protection of building enclosure elements. The entire enclosure of the safe room, including all walls, ceilings, and openings, fixed or operable windows, and all entry doors into the safe room, shall meet or exceed Level D requirements of ASTM E 1996 (Table 422.5-1), or be an approved assembly listed in Section 430.5.4. Any wall or ceiling penetration greater than 4 square inches shall be considered an opening. Exception: Electrical outlet boxes and interior lighting switches not penetrating more than 2.5-inches into the interior wall surface and a plumbing piping or conduit not greater than 1.5-inch in diameter shall be exempted from this requirement. _____ 429.5.3 Cyclic pressure loading of glazing and protective systems. Impact protective systems shall meet the ASTM E 1996 cyclic pressure requirement for the loading given in Table 429.5-1. Table 429.5-1 — Windborne Debris Protection and Cyclic Pressure Criteria for Residential Safe Rooms ASTM E 1996 Missile Level Rating Debris Missile Size Debris Impact Speed Enclosure Wall Ceiling, and Floor Cyclic Air Pressure Testing - maximum inward and maximum outward pressure D 2 × 4 weighing 9.0 lb. +/- 0.25 lb. and with min. length 8 ft. +/- 4-inch 50 ft/sec. or at least 34 mph 35 psf inward 45 psf outward   _____ 429.5.4 Approved Debris Impact Resistant Wall Assemblies. The following methods of wall assembly construction shall be deemed to comply with section 429.5.2: 1. ¾-inch plywood on wood studs spaced at 16 inches on-center with #8×3 inch wood screws at 6 inches on-center. 2. ¾-inch plywood attached to double studs spaced at 16 inches on-center with #8×3 inch wood screws at 6 inches on-center. 3. 8 ¼ inch cementitious lap siding over 22 gage sheet metal attached to 350S-162-33 studs spaced at 24 inches on-center. 4. 8 ¼ inch cementitious lap siding attached to 350S-162-33 studs spaced at 24 inches on-center studs with interior ¾-inch interior plywood sheathing. 5. 8 ¼ inch cementitious lap siding attached to 350S-162-33 studs spaced at 24 inches on-center with ½-inch interior 22 gage sheet metal composite gypsum wallboard. 6. 8 ¼ inch cementitious lap siding attached to 2 inch × 4 inch wood studs spaced at 16 inches on-center with ½-inch interior 22 gage sheet metal composite gypsum wallboard. 7. 8 ¼ inch cementitious lap siding attached to 2 inch × 4 inch wood studs spaced at 16 inches on-center with 22 gage sheet metal and ½-inch interior gypsum wallboard. 8. Cementitious lap siding attached to 5/8-inch structural plywood on 2 inch × 4 inch wood studs spaced at 16 inches on-center. 9. Cementitious-panel siding attached to 5/8-inch structural plywood on 2 inch × 4 inch or 362S-137-43 steel studs spaced at 16 inches on-center. 10. EFS with ½-inch dens-glass gold exterior sheathing on 362S-137-43 steel studs spaced at 16 inches on-center and ½-inch interior gypsum wallboard. 11. 24 gage steel sheet (50 ksi) on girts. 12. Concrete with a thickness of 4 inches with reinforcing. 13. Concrete masonry units with a thickness of 6 inches with partial grouting and reinforcing spaced at 24 inches on-center. 14. Concrete masonry units with a thickness of 8 inches with partial grouting and reinforcing spaced at 24 inches on-center. 15. Interior or exterior wall with laterally braced 2 inch × 4 inch wood studs with sheathing on either side of 22 gage sheet metal. 16. Sheathing shall be attached to studs with fasteners at 6 inches (152 mm) on center for edge and field fastening. 429.6 Ventilation. The residential safe room shall be naturally ventilated to allow the enclosure to have approximately one air change every two hours. This requirement may be satisfied by 12 square inches of venting per occupant. There shall be at least two operable vents. The vents shall be protected by a cowling or other device that shall be impact tested to comply with ASTM E 1996-14 Level D. Alternatively, the room shall be evaluated to determine if the openings are of sufficient area to constitute an open or partially enclosed condition as defined in ASCE 7. 429.7 Communications. The residential safe room shall be equipped with a phone line and telephone that does not rely on a separate electrical power outlet. Alternatively, a wireless telephone shall be permitted to rely on an Uninterruptible Power Supply (UPS) battery device. 429.8 Construction documents. Construction documents for the residential safe room shall be directly prepared by a Hawaiʻi licensed professional structural engineer. 429.9 Special inspection. The construction or installation of the residential safe room shall be verified for conformance to the drawings in accordance with the appropriate requirements of chapter 17. 429.10 Notification. The owner of the safe room shall notify the state department of defense and county civil defense agency of the property's tax map key or global positioning system coordinates. ( Ord. No. 5508 , § 3, 2023)