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SECTION R403 FOOTINGS

R403.1 General. All exterior walls shall be supported on continuous solid or fully grouted masonry or concrete footings, crushed stone footings, wood foundations, or other approved structural systems which shall be of sufficient design to accommodate all loads according to Section R301 and to transmit the resulting loads to the soil within the limitations as determined from the character of the soil. Footings shall be supported on undisturbed natural soils or engineered fill. Concrete footing shall be designed and constructed in accordance with the provisions of Section R403 or in accordance with ACI 332.

TABLE R403.1 MINIMUM WIDTH OF CONCRETE, PRECAST OR MASONRY FOOTINGS (inches)a

 
LOAD-BEARING VALUE OF SOIL (psf)
1,500
2,000
3,000
≥ 4,000
Conventional light-frame construction
1-story
12
12
12
12
2-story
15
12
12
12
3-story
23
17
12
12
4-inch brick veneer over light frame or 8-inch hollow concrete masonry
1-story
12
12
12
12
2-story
21
16
12
12
3-story
32
24
16
12
8-inch solid or fully grouted masonry
1-story
16
12
12
12
2-story
29
21
14
12
3-story
42
32
21
16

 
For SI: 1 inch = 25.4 mm, 1 pound per square foot = 0.0479 kPa.

a. Where minimum footing width is 12 inches, use of a single wythe of solid or fully grouted 12-inch nominal concrete masonry units is permitted.


R403.1.1 Minimum size. Minimum sizes for concrete and masonry footings shall be as set forth in Table R403.1 and Figure R403.1(1). The footing width, W, shall be based on the load-bearing value of the soil in accordance with Table R401.4.1. Spread footings shall be at least 6 inches (152 mm) in thickness, T. Footing projections, P, shall be at least 2 inches (51 mm) and shall not exceed the thickness of the footing. The size of footings supporting piers and columns shall be based on the tributary load and allowable soil pressure in accordance with Table R401.4.1. Footings for wood foundations shall be in accordance with the details set forth in Section R403.2, and Figures R403.1(2) and R403.1(3).
R403.1.2 Continuous footing in Seismic Design Categories D0, D1 and D2. The braced wall panels at exterior walls of buildings located in Seismic Design Categories D0, D1 and D2 shall be supported by continuous footings. All required interior braced wall panels in buildings with plan dimensions greater than 50 feet (15 240 mm) shall also be supported by continuous footings.
R403.1.3 Seismic reinforcing. Concrete footings located in Seismic Design Categories D0, D1 and D2, as established in Table R301.2(1), shall have minimum reinforcement. Bottom reinforcement shall be located a minimum of 3 inches (76 mm) clear from the bottom of the footing.

In Seismic Design Categories D0, D1 and D2 where a construction joint is created between a concrete footing and a stem wall, a minimum of one No. 4 bar shall be installed at not more than 4 feet (1219 mm) on center. The vertical bar shall extend to 3 inches (76 mm) clear of the bottom of the footing, have a standard hook and extend a minimum of 14 inches (357 mm) into the stem wall.

In Seismic Design Categories D0, D1 and D2 where a grouted masonry stem wall is supported on a concrete footing and stem wall, a minimum of one No. 4 bar shall be installed at not more than 4 feet (1219 mm) on center. The vertical bar shall extend to 3 inches (76 mm) clear of the bottom of the footing and have a standard hook.

In Seismic Design Categories D0, D1 and D2 masonry stem walls without solid grout and vertical reinforcing are not permitted.

Exception: In detached one- and two-family dwellings which are three stories or less in height and constructed with stud bearing walls, plain concrete footings without longitudinal reinforcement supporting walls and isolated plain concrete footings supporting columns or pedestals are permitted.
R403.1.3.1 Foundations with stemwalls. Foundations with stem walls shall have installed a minimum of one No. 4 bar within 12 inches (305 mm) of the top of the wall and one No. 4 bar located 3 inches (76 mm) to 4 inches (102 mm) from the bottom of the footing.
R403.1.3.2 Slabs-on-ground with turned-down footings. Slabs on ground with turned down footings shall have a minimum of one No. 4 bar at the top and the bottom of the footing.

Exception: For slabs-on-ground cast monolithically with the footing, locating one No. 5 bar or two No. 4 bars in the middle third of the footing depth shall be permitted as an alternative to placement at the footing top and bottom.

Where the slab is not cast monolithically with the footing, No. 3 or larger vertical dowels with standard hooks on each end shall be provided in accordance with Figure R403.1.3.2. Standard hooks shall comply with Section R611.5.4.5.







For SI: 1 inch = 25.4 mm.

FIGURE R403.1(1) CONCRETE AND MASONRY FOUNDATION DETAILS





For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 mil = 0.0254 mm.

FIGURE R403.1(2) PERMANENT WOOD FOUNDATION BASEMENT WALL SECTION





For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 mil = 0.0254 mm.

FIGURE R403.1(3) PERMANENT WOOD FOUNDATION CRAWL SPACE SECTION





For SI: 1 inch = 25.4 mm.

FIGURE R403.1.3.2 DOWELS FOR SLABS-ON-GROUND WITH TURNED-DOWN FOOTINGS
R403.1.4 Minimum depth. All exterior footings shall be placed at least 12 inches (305 mm) below the undisturbed ground surface. Where applicable, the depth of footings shall also conform to Sections R403.1.4.1 through R403.1.4.2.
R403.1.4.1 Frost protection. Except where otherwise protected from frost, foundation walls, piers and other permanent supports of buildings and structures shall be protected from frost by one or more of the following methods:
1. Extended below the frost line specified in Table R301.2.(1);
2. Constructing in accordance with Section R403.3;
3. Constructing in accordance with ASCE 32; or
4. Erected on solid rock.

Exceptions:
1. Protection of freestanding accessory structures with an area of 600 square feet (56 m2) or less, of light-frame construction, with an eave height of 10 feet (3048 mm) or less shall not be required.
2. Protection of freestanding accessory structures with an area of 400 square feet (37 m2) or less, of other than light-frame construction, with an eave height of 10 feet (3048 mm) or less shall not be required.
3. Decks not supported by a dwelling need not be provided with footings that extend below the frost line.


Footings shall not bear on frozen soil unless the frozen condition is permanent.
R403.1.4.2 Seismic conditions. In Seismic Design Categories D0, D1 and D2, interior footings supporting bearing or bracing walls and cast monolithically with a slab on grade shall extend to a depth of not less than 12 inches (305 mm) below the top of the slab.
R403.1.5 Slope. The top surface of footings shall be level. The bottom surface of footings shall not have a slope exceeding one unit vertical in 10 units horizontal (10-percent slope). Footings shall be stepped where it is necessary to change the elevation of the top surface of the footings or where the slope of the bottom surface of the footings will exceed one unit vertical in ten units horizontal (10-percent slope).
R403.1.6 Foundation anchorage. Sill plates and walls supported directly on continuous foundations shall be anchored to the foundation in accordance with this section.

Wood sole plates at all exterior walls on monolithic slabs, wood sole plates of braced wall panels at building interiors on monolithic slabs and all wood sill plates shall be anchored to the foundation with anchor bolts spaced a maximum of 6 feet (1829 mm) on center. Bolts shall be at least 1/2 inch (12.7 mm) in diameter and shall extend a minimum of 7 inches (178 mm) into concrete or grouted cells of concrete masonry units. A nut and washer shall be tightened on each anchor bolt. There shall be a minimum of two bolts per plate section with one bolt located not more than 12 inches (305 mm) or less than seven bolt diameters from each end of the plate section. Interior bearing wall sole plates on monolithic slab foundation that are not part of a braced wall panel shall be positively anchored with approved fasteners. Sill plates and sole plates shall be protected against decay and termites where required by Sections R317 and R318. Cold-formed steel framing systems shall be fastened to wood sill plates or anchored directly to the foundation as required in Section R505.3.1 or R603.3.1.

Exceptions:
1. Foundation anchorage, spaced as required to provide equivalent anchorage to 1/2-inch-diameter (12.7 mm) anchor bolts.
2. Walls 24 inches (610 mm) total length or shorter connecting offset braced wall panels shall be anchored to the foundation with a minimum of one anchor bolt located in the center third of the plate section and shall be attached to adjacent braced wall panels at corners as shown in Figure R602.10.4.4(1).
3. Connection of walls 12 inches (305 mm) total length or shorter connecting offset braced wall panels to the foundation without anchor bolts shall be permitted. The wall shall be attached to adjacent braced wall panels at corners as shown in Figure R602.10.4.4(1).
R403.1.6.1 Foundation anchorage in Seismic Design Categories C, D0, D1 and D2. In addition to the requirements of Section R403.1.6, the following requirements shall apply to wood light-frame structures in Seismic Design Categories D0, D1 and D2 and wood light-frame townhouses in Seismic Design Category C.
1. Plate washers conforming to Section R602.11.1 shall be provided for all anchor bolts over the full length of required braced wall lines except where approved anchor straps are used. Properly sized cut washers shall be permitted for anchor bolts in wall lines not containing braced wall panels.
2. Interior braced wall plates shall have anchor bolts spaced at not more than 6 feet (1829 mm) on center and located within 12 inches (305 mm) of the ends of each plate section when supported on a continuous foundation.
3. Interior bearing wall sole plates shall have anchor bolts spaced at not more than 6 feet (1829 mm) on center and located within 12 inches (305 mm) of the ends of each plate section when supported on a continuous foundation.
4. The maximum anchor bolt spacing shall be 4 feet (1219 mm)for buildings over two stories in height.
5. Stepped cripple walls shall conform to Section R602.11.2.
6. Where continuous wood foundations in accordance with Section R404.2 are used, the force transfer shall have a capacity equal to or greater than the connections required by Section R602.11.1 or the braced wall panel shall be connected to the wood foundations in accordance with the braced wall panel-to-floor fastening requirements of Table R602.3(1).
R403.1.7 Footings on or adjacent to slopes. The placement of buildings and structures on or adjacent to slopes steeper than one unit vertical in three units horizontal (33.3-percent slope) shall conform to Sections R403.1.7.1 through R403.1.7.4.
R403.1.7.1 Building clearances from ascending slopes. In general, buildings below slopes shall be set a sufficient distance from the slope to provide protection from slope drainage, erosion and shallow failures. Except as provided in Section R403.1.7.4 and Figure R403.1.7.1, the following criteria will be assumed to provide this protection. Where the existing slope is steeper than one unit vertical in one unit horizontal (100-percent slope), the toe of the slope shall be assumed to be at the intersection of a horizontal plane drawn from the top of the foundation and a plane drawn tangent to the slope at an angle of 45 degrees (0.79 rad) to the horizontal. Where a retaining wall is constructed at the toe of the slope, the height of the slope shall be measured from the top of the wall to the top of the slope.





For SI: 1 foot = 304.8 mm.

FIGURE R403.1.7.1 FOUNDATION CLEARANCE FROM SLOPES
R403.1.7.2 Footing setback from descending slope surfaces. Footings on or adjacent to slope surfaces shall be founded in material with an embedment and setback from the slope surface sufficient to provide vertical and lateral support for the footing without detrimental settlement. Except as provided for in Section R403.1.7.4 and Figure R403.1.7.1, the following setback is deemed adequate to meet the criteria. Where the slope is steeper than one unit vertical in one unit horizontal (100-percent slope), the required setback shall be measured from an imaginary plane 45 degrees (0.79 rad) to the horizontal, projected upward from the toe of the slope.
R403.1.7.3 Foundation elevation. On graded sites, the top of any exterior foundation shall extend above the elevation of the street gutter at point of discharge or the inlet of an approved drainage device a minimum of 12 inches (305 mm) plus 2 percent. Alternate elevations are permitted subject to the approval of the building official, provided it can be demonstrated that required drainage to the point of discharge and away from the structure is provided at all locations on the site.
R403.1.7.4 Alternate setback and clearances. Alternate setbacks and clearances are permitted, subject to the approval of the building official. The building official is permitted to require an investigation and recommendation of a qualified engineer to demonstrate that the intent of this section has been satisfied. Such an investigation shall include consideration of material, height of slope, slope gradient, load intensity and erosion characteristics of slope material.
R403.1.8 Foundations on expansive soils. Foundation and floor slabs for buildings located on expansive soils shall be designed in accordance with Section 1808.6 of the California Building Code.

Exception: Slab-on-ground and other foundation systems which have performed adequately in soil conditions similar to those encountered at the building site are permitted subject to the approval of the building official.
R403.1.8.1 Expansive soils classifications. Soils meeting all four of the following provisions shall be considered expansive, except that tests to show compliance with Items 1, 2 and 3 shall not be required if the test prescribed in Item 4 is conducted:
1. Plasticity Index (PI) of 15 or greater, determined in accordance with ASTM D 4318.
2. More than 10 percent of the soil particles pass a No. 200 sieve (75 μm), determined in accordance with ASTM D 422.
3. More than 10 percent of the soil particles are less than 5 micrometers in size, determined in accordance with ASTM D 422.
4. Expansion Index greater than 20, determined in accordance with ASTM D 4829.
R403.2 Footings for wood foundations. Footings for wood foundations shall be in accordance with Figures R403.1(2) and R403.1(3). Gravel shall be washed and well graded. The maximum size stone shall not exceed 3/4 inch (19.1 mm). Gravel shall be free from organic, clayey or silty soils. Sand shall be coarse, not smaller than 1/16-inch (1.6 mm) grains and shall be free from organic, clayey or silty soils. Crushed stone shall have a maximum size of 1/2 inch (12.7 mm).

R403.3 Frost protected shallow foundations. For buildings where the monthly mean temperature of the building is maintained at a minimum of 64°F (18°C), footings are not required to extend below the frost line when protected from frost by insulation in accordance with Figure R403.3(1) and Table R403.3(1). Foundations protected from frost in accordance with Figure R403.3(1) and Table R403.3(1) shall not be used for unheated spaces such as porches, utility rooms, garages and carports, and shall not be attached to basements or crawl spaces that are not maintained at a minimum monthly mean temperature of 64°F (18°C).

Materials used below grade for the purpose of insulating footings against frost shall be labeled as complying with ASTM C 578.




For SI: 1 inch = 25.4 mm.

a. See Table R403.3(1) for required dimensions and R-values for vertical and horizontal insulation and minimum footing depth.

FIGURE R403.3(1) INSULATION PLACEMENT FOR FROST PROTECTED FOOTINGS IN HEATED BUILDINGS


TABLE R403.3(1) MINIMUM FOOTING DEPTH AND INSULATION REQUIREMENTS FOR FROST-PROTECTED FOOTINGS IN HEATED BUILDINGSa

AIR FREEZING
INDEX (°F-days)b
MINIMUM
FOOTING
DEPTH, D
(inches)
VERTICAL
INSULATION
R
-VALUEc, d
HORIZONTAL INSULATION
R
-VALUEc, e
HORIZONTAL INSULATION DIMENSIONS
PER FIGURE R403.3(1) (inches)
Along walls At corners A B C
1,500 or less 12 4.5 Not required Not required Not required Not required Not required
2,000 14 5.6 Not required Not required Not required Not required Not required
2,500 16 6.7 1.7 4.9 12 24 40
3,000 16 7.8 6.5 8.6 12 24 40
3,500 16 9.0 8.0 11.2 24 30 60
4,000 16 10.1 10.5 13.1 24 36 60

a. Insulation requirements are for protection against frost damage in heated buildings. Greater values may be required to meet energy conservation standards.

b. See Figure R403.3(2) or Table R403.3(2) for Air Freezing Index values.

c. Insulation materials shall provide the stated minimum R-values under long-term exposure to moist, below-ground conditions in freezing climates. The following R-values shall be used to determine insulation thicknesses required for this application: Type II expanded polystyrene—2.4R per inch; Type IV extruded polystyrene—4.5R per inch; Type VI extruded polystyrene—4.5R per inch; Type IX expanded polystyrene—3.2R per inch; Type X extruded polystyrene—4.5R per inch.

d. Vertical insulation shall be expanded polystyrene insulation or extruded polystyrene insulation.

e. Horizontal insulation shall be extruded polystyrene insulation.





For SI: C = [(F) -32]/1.8.

Note: The air-freezing index is defined as cumulative degree days below 32F. It is used as a measure of the combined magnitude and duration of air temperature below freezing. The index was computed over a 12-month period (July-June) for each of the 3,044 stations used in the above analysis. Date from the 1951-80 period were fitted to a Weibull probability distribution to produce an estimate of the 100-year return period.

FIGURE R403.3(2) AIR-FREEZING INDEX AN ESTIMATE OF THE 100-YEAR RETURN PERIOD

TABLE R403.3(2) AIR-FREEZING INDEX FOR U.S. LOCATIONS BY COUNTY

STATE
AIR-FREEZING INDEX
1500 or less
2000
2500
3000
3500
4000
Alabama
All counties
-
-
-
-
-
Alaska
Ketchikan Gateway, Prince of Wales-Outer Ketchikan (CA), Sitka, Wrangell-Petersburg (CA)
-
Aleutians West (CA), Haines, Juneau, Skagway-Hoonah- Angoon (CA), Yakutat
-
-
All counties not listed
Arizona
All counties
-
-
-
-
-
Arkansas
All counties
-
-
-
-
-
California
All counties not listed
Nevada, Sierra
-
-
-
-
Colorado
All counties not listed
Archuleta, Custer, Fremont, Huerfano, Las Animas, Ouray, Pitkin, San Miguel
Clear Creek, Conejos, Costilla, Dolores, Eagle, La Plata, Park, Routt, San Juan, Summit
Alamosa, Grand, Jackson, Larimer, Moffat, Rio Blanco, Rio Grande
Chaffee, Gunnison, Lake, Saguache
Hinsdale, Mineral
Connecticut
All counties not listed
Hartford, Litchfield
-
-
-
-
Delaware
All counties
-
-
-
-
-
District of Columbia
All counties
-
-
-
-
-
Florida
All counties
-
-
-
-
-
Georgia
All counties
-
-
-
-
-
Hawaii
All counties
-
-
-
-
-
Idaho
All counties not listed
Adams, Bannock, Blaine, Clearwater, Idaho, Lincoln, Oneida, Power, Valley, Washington
Bingham, Bonneville, Camas, Caribou, Elmore, Franklin, Jefferson, Madison, Teton
Bear Lake, Butte, Custer, Fremont, Lemhi
Clark
-
Illinois
All counties not listed
Boone, Bureau, Cook, Dekalb, DuPage, Fulton, Grundy, Henderson, Henry, Iroquois, Jo Daviess, Kane, Kankakee, Kendall, Knox, La Salle, Lake, Lee, Livingston, Marshall, Mason, McHenry, McLean, Mercer, Peoria, Putnam, Rock Island, Stark Tazewell, Warren, Whiteside, Will, Woodford
Carroll, Ogle, Stephenson, Winnebago
-
-
-
Indiana
All counties not listed
Allen, Benton, Cass, Fountain, Fulton, Howard, Jasper, Kosciusko, La Porte, Lake, Marshall, Miami, Newton, Porter, Pulaski, Starke, Steuben, Tippecanoe, Tipton, Wabash, Warren, White
-
-
-
-


(continued)


TABLE R403.3(2)-continued AIR-FREEZING INDEX FOR U.S. LOCATIONS BY COUNTY

STATE
AIR-FREEZING INDEX
1500 or less
2000
2500
3000
3500
4000
Iowa
Appanoose, Davis, Fremont, Lee, Van Buren
All counties not listed
Allamakee, Black Hawk, Boone, Bremer, Buchanan, Buena Vista, Butler, Calhoun, Cerro Gordo, Cherokee, Chickasaw, Clay, Clayton, Delaware, Dubuque, Fayette, Floyd, Franklin, Grundy, Hamilton, Hancock, Hardin, Humboldt, Ida, Jackson, Jasper, Jones, Linn, Marshall, Palo Alto, Plymouth, Pocahontas, Poweshiek, Sac, Sioux, Story, Tama, Webster, Winnebago, Woodbury, Worth, Wright
Dickinson, Emmet, Howard, Kossuth, Lyon, Mitchell, O'Brien, Osceola, Winneshiek
-
-
Kansas
All counties
-
-
-
-
-
Kentucky
All counties
-
-
-
-
-
Louisiana
All counties
-
-
-
-
-
Maine
York
Knox, Lincoln, Sagadahoc
Androscoggin, Cumberland, Hancock, Kennebec, Waldo, Washington
Aroostook, Franklin, Oxford, Penobscot, Piscataquis, Somerset
-
-
Maryland
All counties
-
-
-
-
-
Massachusetts
All counties not listed
Berkshire, Franklin, Hampden, Worcester
-
-
-
-
Michigan
Berrien, Branch, Cass, Kalamazoo, Macomb, Ottawa, St. Clair, St. Joseph
All counties not listed
Alger, Charlevoix, Cheboygan, Chippewa, Crawford, Delta, Emmet, Iosco, Kalkaska, Lake, Luce, Mackinac, Menominee, Missaukee, Montmorency, Ogemaw, Osceola, Otsego, Roscommon, Schoolcraft, Wexford
Baraga, Dickinson, Iron, Keweenaw, Marquette
Gogebic, Houghton, Ontonagon
-
Minnesota
-
-
Houston, Winona
All counties not listed
Aitkin, Big Stone, Carlton, Crow Wing, Douglas, Itasca, Kanabec, Lake, Morrison, Pine, Pope, Stearns, Stevens, Swift, Todd, Wadena
Becker, Beltrami, Cass, Clay, Clearwater, Grant, Hubbard, Kittson, Koochiching, Lake of the Woods, Mahnomen, Marshall, Norman, Otter Tail, Pennington, Polk, Red Lake, Roseau, St Louis, Traverse, Wilkin
Mississippi
All counties
-
-
-
-
-
Missouri
All counties not listed
Atchison, Mercer, Nodaway, Putnam
-
-
-
-


(continued)


TABLE R403.3(2)-continued AIR-FREEZING INDEX FOR U.S. LOCATIONS BY COUNTY

STATE
AIR-FREEZING INDEX
1500 or less
2000
2500
3000
3500
4000
Montana
Mineral
Broadwater, Golden Valley, Granite, Lake, Lincoln, Missoula, Ravalli, Sanders, Sweet Grass
Big Horn, Carbon, Jefferson, Judith Basin, Lewis and Clark, Meagher, Musselshell, Powder River, Powell, Silver Bow, Stillwater, Westland
Carter, Cascade, Deer Lodge, Falcon, Fergus, Flathead, Gallanting, Glacier, Madison, Park, Petroleum, Ponder, Rosebud, Teton, Treasure, Yellowstone
Beaverhead, Blaine, Chouteau, Custer, Dawson, Garfield, Liberty, McCone, Prairie, Toole, Wibaux
Daniels, Hill, Phillips, Richland, Roosevelt, Sheridan, Valley
Nebraska
Adams, Banner, Chase, Cheyenne, Clay, Deuel, Dundy, Fillmore, Franklin, Frontier, Furnas, Gage, Garden, Gosper, Harlan, Hayes, Hitchcock, Jefferson, Kimball, Morrill, Nemaha, Nuckolls, Pawnee, Perkins, Phelps, Red Willow, Richardson, Saline, Scotts Bluff, Seward, Thayer, Webster
All counties not listed
Boyd, Burt, Cedar, Cuming, Dakota, Dixon, Dodge, Knox, Thurston
-
-
-
Nevada
All counties not listed
Elko, Eureka, Nye, Washoe, White Pine
-
-
-
-
New Hampshire
-
All counties not listed
-
-
-
Carroll, Coos, Grafton
New Jersey
All counties
-
-
-
-
-
New Mexico
All counties not listed
Rio Arriba
Colfax, Mora, Taos
-
-
-
New York
Albany, Bronx, Cayuga, Columbia, Cortland, Dutchess, Genessee, Kings, Livingston, Monroe, Nassau, New York, Niagara, Onondaga, Ontario, Orange, Orleans, Putnam, Queens, Richmond, Rockland, Seneca, Suffolk, Wayne, Westchester, Yates
All counties not listed
Clinton, Essex, Franklin, Hamilton, Herkimer, Jefferson, Lewis, St. Lawrence, Warren
-
-
-
North Carolina
All counties
-
-
-
-
-
North Dakota
-
-
-
Billings, Bowman
Adams, Dickey, Golden Valley, Hettinger, LaMoure, Oliver, Ransom, Sargent, Sioux, Slope, Stark
All counties not listed
Ohio
All counties not listed
Ashland, Crawford, Defiance, Holmes, Huron, Knox, Licking, Morrow, Paulding, Putnam, Richland, Seneca, Williams
-
-
-
-


(continued)


TABLE R403.3(2)-continued AIR-FREEZING INDEX FOR U.S. LOCATIONS BY COUNTY

STATE
AIR-FREEZING INDEX
1500 or less
2000
2500
3000
3500
4000
Oklahoma
All counties
-
-
-
-
-
Oregon
All counties not listed
Baker, Crook, Grant, Harney
-
-
-
-
Pennsylvania
All counties not listed
Berks, Blair, Bradford, Cambria, Cameron, Centre, Clarion, Clearfield, Clinton, Crawford, Elk, Forest, Huntingdon, Indiana, Jefferson, Lackawanna, Lycoming, McKean, Pike, Potter, Susquehanna, Tioga, Venango, Warren, Wayne, Wyoming
-
-
-
-
Rhode Island
All counties
-
-
-
-
-
South Carolina
All counties
-
-
-
-
-
South Dakota
-
Bennett, Custer, Fall River, Lawrence, Mellette, Shannon, Todd, Tripp
Bon Homme, Charles Mix, Davison, Douglas, Gregory, Jackson, Jones, Lyman
All counties not listed
Beadle, Brookings, Brown, Campbell, Codington, Corson, Day, Deuel, Edmunds, Faulk, Grant, Hamlin, Kingsbury, Marshall, McPherson, Perkins, Roberts, Spink, Walworth
-
Tennessee
All counties
-
-
-
-
-
Texas
All counties
-
-
-
-
-
Utah
All counties not listed
Box Elder, Morgan, Weber
Garfield, Salt Lake, Summit
Carbon, Daggett, Duchesne, Rich, Sanpete, Uintah, Wasatch
-
-
Vermont
-
Bennington, Grand Isle, Rutland, Windham
Addison, Chittenden, Franklin, Orange, Washington, Windsor
Caledonia, Essex, Lamoille, Orleans
-
-
Virginia
All counties
-
-
-
-
-
Washington
All counties not listed
Chelan, Douglas, Ferry, Okanogan
-
-
-
-
West Virginia
All counties
-
-
-
-
-
Wisconsin
-
Kenosha, Kewaunee, Racine, Sheboygan, Walworth
All counties not listed
Ashland, Barron, Burnett, Chippewa, Clark, Dunn, Eau Claire, Florence, Forest, Iron, Jackson, La Crosse, Langlade, Marathon, Monroe, Pepin, Polk, Portage, Price, Rust, St. Croix, Taylor, Trempealeau, Vilas, Wood
Bayfield, Douglas, Lincoln, Oneida, Sawyer, Washburn
-
Wyoming
Goshen, Platte
Converse, Crook, Laramie, Niobrara
Campbell, Carbon, Hot Springs, Johnson, Natrona, Sheridan, Uinta, Weston
Albany, Big Horn, Park, Washakie
Fremont, Teton
Lincoln, Sublette, Sweetwater






For SI: 1 inch = 25.4 mm.
a. See Table R403.3(1) for required dimensions and R-values for vertical and horizontal insulation.


FIGURE R403.3(3) INSULATION PLACEMENT FOR FROST-PROTECTED FOOTINGS ADJACENT TO UNHEATED SLAB-ON-GROUND STRUCTURE





FIGURE R403.3(4) INSULATION PLACEMENT FOR FROST-PROTECTED FOOTINGS ADJACENT TO HEATED STRUCTURE

R403.3.1 Foundations adjoining frost protected shallow foundations. Foundations that adjoin frost protected shallow foundations shall be protected from frost in accordance with Section R403.1.4.
R403.3.1.1 Attachment to unheated slab-on-ground structure. Vertical wall insulation and horizontal insulation of frost protected shallow foundations that adjoin a slab-on-ground foundation that does not have a monthly mean temperature maintained at a minimum of 64°F (18°C) shall be in accordance with Figure R403.3(3) and Table R403.3(1). Vertical wall insulation shall extend between the frost protected shallow foundation and the adjoining slab foundation. Required horizontal insulation shall be continuous under the adjoining slab foundation and through any foundation walls adjoining the frost protected shallow foundation. Where insulation passes through a foundation wall, it shall either be of a type complying with this section and having bearing capacity equal to or greater than the structural loads imposed by the building, or the building shall be designed and constructed using beams, lintels, cantilevers or other means of transferring building loads such that the structural loads of the building do not bear on the insulation.
R403.3.1.2 Attachment to heated structure. Where a frost protected shallow foundation abuts a structure that has a monthly mean temperature maintained at a minimum of 64°F (18°C), horizontal insulation and vertical wall insulation shall not be required between the frost protected shallow foundation and the adjoining structure. Where the frost protected shallow foundation abuts the heated structure, the horizontal insulation and vertical wall insulation shall extend along the adjoining foundation in accordance with Figure R403.3(4) a distance of not less than Dimension A in Table R403.3(1).

Exception: Where the frost protected shallow foundation abuts the heated structure to form an inside corner, vertical insulation extending along the adjoining foundation is not required.
R403.3.2 Protection of horizontal insulation below ground. Horizontal insulation placed less than 12 inches (305 mm) below the ground surface or that portion of horizontal insulation extending outward more than 24 inches (610 mm) from the foundation edge shall be protected against damage by use of a concrete slab or asphalt paving on the ground surface directly above the insulation or by cementitious board, plywood rated for below-ground use, or other approved materials placed below ground, directly above the top surface of the insulation.
R403.3.3 Drainage. Final grade shall be sloped in accordance with Section R401.3. In other than Group I Soils, as detailed in Table R405.1, gravel or crushed stone beneath horizontal insulation below ground shall drain to daylight or into an approved sewer system.
R403.3.4 Termite damage. The use of foam plastic in areas of "very heavy" termite infestation probability shall be in accordance with Section R318.4.
R403.4 Footings for precast concrete foundations. Footings for precast concrete foundations shall comply with Section R403.4.

TABLE R403.4 MINIMUM DEPTH OF CRUSHED STONE FOOTINGS (D), (inches)

 
LOAD BEARING VALUE OF SOIL (psf)
1500
2000
3000
4000
MH, CH, CL, ML
SC, GC, SM, GM, SP, SW
GP, GW
 
Wall width (inches)
Wall width (inches)
Wall width (inches)
Wall width (inches)
6
8
10
12
6
8
10
12
6
8
10
12
6
8
10
12
Conventional light-frame construction
1-story
1100 plf
6
4
4
4
6
4
4
4
6
4
4
4
6
4
4
4
2-story
1800 plf
8
6
4
4
6
4
4
4
6
4
4
4
6
4
4
4
3-story
2000 plf
16
14
12
10
10
8
6
6
6
4
4
4
6
4
4
4
4-inch brick veneer over light-frame or 8-inch hollow concrete masonry
1-story
1500 plf
6
4
4
4
6
4
4
4
6
4
4
4
6
4
4
4
2-story
2700 plf
14
12
10
8
10
8
6
4
6
4
4
4
6
4
4
4
3-story
4000 plf
22
22
20
18
16
14
12
10
10
8
6
4
6
4
4
4
8-inch solid or fully grouted masonry
1-story
2000 plf
10
8
6
4
6
4
4
4
6
4
4
4
6
4
4
4
2-story
3600 plf
20
18
16
16
14
12
10
8
8
6
4
4
6
4
4
4
3-story
5300 plf
32
30
28
26
22
22
20
18
14
12
10
8
10
8
6
4


For SI: 1 inch = 25.4 mm, 1 pound per square inch = 6.89 kPa.





FIGURE R403.4(1) BASEMENT OR CRAWL SPACE WITH PRECAST FOUNDATION WALL BEARING ON CRUSHED STONE





FIGURE R403.4(2) BASEMENT OR CRAWL SPACE WITH PRECAST FOUNDATION WALL ON SPREAD FOOTING

R403.4.1 Crushed stone footings. Clean crushed stone shall be free from organic, clayey or silty soils. Crushed stone shall be angular in nature and meet ASTM C 33, with the maximum size stone not to exceed 1/2 inch (12.7 mm) and the minimum stone size not to be smaller than 1/16-inch (1.6 mm). Crushed stone footings for precast foundations shall be installed in accordance with Figure R403.4(1) and Table R403.4. Crushed stone footings shall be consolidated using a vibratory plate in a maximum of 8-inch lifts. Crushed stone footings shall be limited to Seismic Design Categories A, B and C.
R403.4.2 Concrete footings. Concrete footings shall be installed in accordance with Section R403.1 and Figure R403.4(2).