Section 12-B301. R301 - DESIGN CRITERIA

 

Strike Table R301.2(1), Climatic and Geographic Design Criteria, in the International Residential Code in its entirety and insert new Table R301.2(1) in the Residential Code in its place to read as follows:

TABLE R301.2(1)
CLIMATIC AND GEOGRAPHIC DESIGN CRITERIA

GROUND SNOW LOAD

WIND DESIGN

SEISMIC DESIGN CATEGORYf

SUBJECT TO DAMAGE FROM

WINTER DESIGN TEMPe

ICE BARRIER UNDERLAY-MENT REQUIREDh

FLOOD HAZARDSg

AIR FREEZING INDEXi

Speedd (mph)

Topographic effectsk

Weatheringa

Frost line depthb

Termitec

MEAN ANNUAL TEMPj

25

90

Na

A

M

30

M-H

17

N

(a) November 15, 1985. (b) November 15, 1985; September 27, 2010. (c) All current FIRMs dated 09/27/2010; Panel numbers 110001IND0A, 1100010002C, 1100010003C, 1100010004C, 1100010006C, 1100010008C, 1100010011C, 1100010012C, 1100010014C, 1100010016C, 1100010018C, 1100010019C, 1100010036C, 1100010037C, 1100010038C, 1100010039C, 1100010041C, 1100010043C, 1100010056C, 1100010057C, 1100010058C, 1100010059C, 1100010066C, 1100010067C, 1100010076C, 1100010077C and 1100010078C.

500

55

For SI: 1 pound per square foot = 0.0479 kPa, 1 mile per hour = 0.447 m/s.

a. Weathering may require a higher strength concrete or grade of masonry than necessary to satisfy the structural requirements of this code.  The weathering column shall be filled in with the weathering index (i.e., “negligible,” “moderate” or “severe”) for concrete as determined from the Weathering Probability Map [Figure R301.2(3)].  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.

b. The frost line depth may require deeper footings than indicated in Figure R403.1(1).  The jurisdiction shall fill in the frost line depth column with the minimum depth of footing below finish grade.

c. 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.

d. The jurisdiction shall fill in this part of the table with the wind speed from the basic wind speed map [Figure R301.2(4)A].  Wind exposure category shall be determined on a site-specific basis in accordance with Section R301.2.1.4.

e. The outdoor design dry-bulb temperature shall be selected from the columns of 971/2-percent values for winter from Appendix D of the International Plumbing Code.  Deviations from the Appendix D temperatures shall be permitted to reflect local climates or local weather experience as determined by the building official.

f. The jurisdiction shall fill in this part of the table with the seismic design category determined from Section R301.2.2.1.

g. The jurisdiction shall fill in this part of the table with (a) 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), (b) the date(s) of the Flood Insurance Study and (c) the panel numbers and dates of all currently effective FIRMs and FBFMs or other flood hazard map adopted by the authority having jurisdiction, as amended.

h. In accordance with Sections R905.2.7.1, 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.”

i. 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)” at www.ncdc.noaa.gov/fpsf.html.

j. 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)” at www.ncdc.noaa.gov/fpsf.html.

k. 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.

 

 

 

 

authority

Section 10 of the Construction Codes Approval and Amendments Act of 1986 (Act), effective March 21, 1987 (D.C. Law 6-216; D.C. Official Code § 6-1409 (2012 Repl.)) and Mayor’s Order 2009-22, dated February 25, 2009, as amended.

source

Final Rulemaking published at 61 DCR 3063 (March 28, 2014 – Part 2).

EditorNote

The District of Columbia Residential Code (2013), referred to as the “Residential Code,” consists of the 2012 edition of the International Residential Code for One- and Two-Family Dwellings, published by the International Code Council (ICC), as amended by the District of Columbia Residential Code Supplement (2013) (12 DCMR B). The International Residential Code is copyrighted by the ICC and therefore is not republished here. However, a copy of the text may be obtained at:http://publicecodes.cyberregs.com/icod/irc/2012/index.htm?bu=IC-P-2012-000002&bu2=IC-P-2012-000019.