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A. IRC Table R301.2(1) Amended. International Residential Code Table R301.2(1) is hereby amended to read as follows:

IRC Table R301.2(1)

Climatic and Geographic Design Criteria

ROOF SNOW LOAD a (psf)

WIND DESIGN

SEISMIC DESIGN CATEGORY

SUBJECT TO DAMAGE FROM

OUTSIDE DESIGN TEMP (F) – HEAT/COOL

ICE BARRIER UNDER-LAYMENT REQUIRED

FLOOD HAZARDS e

AIR FREEZING INDEX

MEAN ANNUAL TEMP

Speed b (mph)

Topographic effects c

Special wind region

Windborne debris zone

Weathering d

Frost Line Depth

Termite

25

110

Yes

No

No

D2

Moderate

12"

Slight to Moderate

83/24

No

N.A.

113

53

MANUAL J DESIGN CRITERIA

Elevation

Latitude

Winter heating

Summer cooling

Altitude correction factor

Indoor design temperature

Design temperature cooling

Heating temperature difference

338 feet

47º 34'39"

72ºF max

75ºF min

0.99

72ºF

75ºF

48ºF

Cooling temperature difference

Wind velocity heating

Wind velocity cooling

Coincident wet bulb

Daily range

Winter humidity

Summer humidity

8ºF

N.A.

N.A.

66

Medium

75%

68%

aThis is the minimum roof snow load. When using this snow load it will be left to the engineer’s judgment whether to consider drift or sliding snow. However, rain on snow surcharge of 5 psf must be considered for roof slopes less than 5 degrees.

bThe 110 mph Ultimate Design Wind Speed (3-second gust) as adopted by the 2018 IRC/ASCE 7-10 (or if using the IBC for structural design, the 98 mph Basic Design Wind Speed as adopted by the 2018 IBC/ASCE 7-16 may be used).

cWind exposure category and Topographic effects (Wind Speed-up Kzt factor) shall be determined on a site-specific basis by the Engineer of Record (components and cladding need not consider topographic effects unless otherwise determined by the engineer of record).

dWeathering may require a higher strength concrete or grade of masonry than necessary to satisfy the structural requirements of this code. The grade of masonry units shall be determined from ASTM C 34, C 55, C 62, C 73, C 90, C 129, C 145, C 216 or C 652.

eThe City of Mercer Island participates in the National Flood Insurance Program (NFIP); Regular Program (No Special Flood Hazard Area). Further NFIP participation information: CID 530083, Initial FHBM Identified 06/28/74, Initial FIRM Identified 05/16/95, Current Effective Map Date (NSFHA), Reg-Emer Date 06/30/97, 53033C0654G effective 8/19/2020.

B. IRC AV107.2 Added. International Residential Code Appendix V, Section AV107.2 is hereby added as follows:

AV107.2 Fire sprinklers in Existing Buildings. An approved automatic fire sprinkler system shall be installed throughout the residence in existing one-family and two-family dwellings (and townhouses) in accordance with Appendix U when undergoing a remodel or addition when the construction value of all additions, alterations or repairs performed within a sixty-month period exceeds 50% of the value of the residence. Value shall be determined by a method approved by the fire code official.

C. IRC AV107.3 Added. International Residential Code Appendix V, Section AV107.3 is hereby added as follows:

AV107.3 Household Fire Alarm System. An approved Household Fire Alarm System shall be installed throughout the residence in existing one-family and two-family dwellings (and townhouses) that have deficiencies in Fire Flow, hydrants or access. This system shall be installed in accordance with NFPA 72 chapter 29 when undergoing a remodel or addition when the construction value of all additions, alterations or repairs performed within a sixty-month period is within 10% to 50% of the value of the residence. Value shall be determined by a method approved by the fire code official.

(Ord. 21C-01 § 1 (Exh. A); Ord. 17C-01 § 2; Ord. 16C-04 § 2; Ord. 13C-06 § 2; Ord. 10C-03 § 2).