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Buildings shall be constructed in accordance with the provisions of this code as limited by the provisions of this section. Additional criteria shall be established by the local jurisdiction and set forth in Table R301.2.
TABLE R301.2
CLIMATIC AND GEOGRAPHIC DESIGN CRITERIA
GROUND SNOW LOADo WIND DESIGN SEISMIC DESIGN CATEGORYf SUBJECT TO DAMAGE FROM ICE BARRIER UNDERLAYMENT REQUIREDh FLOOD HAZARDSg AIR FREEZING INDEXi MEAN
ANNUAL TEMPj
Speedd (mph) Topographic effectsk Special wind regionl Windborne debris zonem Weatheringa Frost line depthb Termitec
MANUAL J DESIGN CRITERIAn
Elevation Altitude correction factore Coincident wet bulb Indoor winter design relative
humidity
Indoor winter design
dry-bulb temperature
Outdoor winter design
dry-bulb temperature
Heating temperature difference
Latitude Daily range Indoor summer design relative humidity Summer design grains Indoor summer design
dry-bulb temperature
Outdoor summer design
dry-bulb temperature
Cooling temperature difference
For SI: 1 pound per square foot = 0.0479 kPa, 1 mile per hour = 0.447 m/s.
  1. Where weathering requires a higher strength concrete or grade of masonry than necessary to satisfy the structural requirements of this code, the frost line depth strength required for weathering shall govern. The weathering column shall be filled in with the weathering index, "negligible," "moderate" or "severe" for concrete as determined from Figure R301.2(1). The grade of masonry units shall be determined from ASTM C34, ASTM C55, ASTM C62, ASTM C73, ASTM C90, ASTM C129, ASTM C145, ASTM C216 or ASTM C652.
  2. Where the frost line depth requires deeper footings than indicated in Figure R403.1(1), the frost line depth strength required for weathering shall govern. The jurisdiction shall fill in the frost line depth column with the minimum depth of footing below finish grade.
  3. The jurisdiction shall fill in this part of the table to indicate the need for protection depending on whether there has been a history of local subterranean termite damage.
  4. The jurisdiction shall fill in this part of the table with the wind speed from the basic wind speed map [Figure R301.2(2). Wind exposure category shall be determined on a site-specific basis in accordance with Section R301.2.1.4.
  5. The jurisdiction shall fill in this section of the table to establish the design criteria using Table 10A from ACCA Manual J or established criteria determined by the jurisdiction.
  6. The jurisdiction shall fill in this part of the table with the seismic design category determined from Section R301.2.2.1.
  7. The jurisdiction shall fill in this part of the table with: the date of the jurisdiction's entry into the National Flood Insurance Program (date of adoption of the first code or ordinance for management of flood hazard areas); and the title and date of the currently effective Flood Insurance Study or other flood hazard study and maps adopted by the authority having jurisdiction, as amended.
  8. In accordance with Sections R905.1.2, R905.4.3.1, R905.5.3.1, R905.6.3.1, R905.7.3.1 and R905.8.3.1, where there has been a history of local damage from the effects of ice damming, the jurisdiction shall fill in this part of the table with "YES." Otherwise, the jurisdiction shall fill in this part of the table with "NO."
  9. The jurisdiction shall fill in this part of the table with the 100-year return period air freezing index (BF-days) from Figure R403.3(2) or from the 100-year (99 percent) value on the National Climatic Data Center data table "Air Freezing Index-USA Method (Base 32°F)."
  10. The jurisdiction shall fill in this part of the table with the mean annual temperature from the National Climatic Data Center data table "Air Freezing Index-USA Method (Base 32°F)."
  11. In accordance with Section R301.2.1.5, where there is local historical data documenting structural damage to buildings due to topographic wind speed-up effects, the jurisdiction shall fill in this part of the table with "YES." Otherwise, the jurisdiction shall indicate "NO" in this part of the table.
  12. In accordance with Figure R301.2(2), where there is local historical data documenting unusual wind conditions, the jurisdiction shall fill in this part of the table with "YES" and identify any specific requirements. Otherwise, the jurisdiction shall indicate "NO" in this part of the table.
  13. In accordance with Section R301.2.1.2 the jurisdiction shall indicate the wind-borne debris wind zone(s). Otherwise, the jurisdiction shall indicate "NO" in this part of the table.
  14. The jurisdiction shall fill in these sections of the table to establish the design criteria using Table 1a or 1b from ACCA Manual J or established criteria determined by the jurisdiction.
  15. The jurisdiction shall fill in this section of the table using the Ground Snow Loads in Figures R301.2(3) and R301.2(4).
  1. Alaska and Hawaii are classified as severe and negligible, respectively.
  2. Lines defining areas are approximate only. Local conditions may be more or less severe than indicated by region classification. A sever classification is where weather conditions result in significant snowfall combined with extended periods during which there is little or no natural thawing, causing deicing salts to be used extensively.
FIGURE R301.2(1)
WEATHERING PROBABILITY MAP FOR CONCRETEa, b
FIGURE R301.2(2)
ULTIMATE DESIGN WIND SPEEDS
For SI: 1 foot = 34.8 mm, 1 pound per square foot =0.0479 kPa, 1 mile =1.61 km.
  1. In CS areas, site-specific case studies are required to establish ground snow loads. Extreme local variations in ground snow loads in these areas preclude mapping at this scale.
  2. Numbers in parentheses represent the upper elevation limits in feet for the ground snow load values presented below. Site-specific case studies are required to establish ground snow loads at elevations not covered.
FIGURE R301.2(3)
GROUND SNOW LOADS, Pg, FOR THE UNITED STATES (lb/ft2)
For SI: 1 foot = 304.8 mm, 1 pound per square foot = 0.0479 kPa, 1 mile = 1.61 km.
  1. In CS areas, site-specific case studies are required to establish ground snow loads. Extreme local variations in ground snow loads in these areas preclude mapping at this scale.
  2. Numbers in parentheses represent the upper elevation limits in feet for the ground snow load values presented below. Site-specific case studies are required to establish ground snow loads at elevations not covered.
FIGURE R301.2(4)
GROUND SNOW LOADS, Pg, FOR THE UNITED STATES (lb/ft2)
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