UpCodes logo
// CODE SNIPPET

Section 1807 Foundation Walls, Retaining Walls and Embedded Posts and Poles

Building Code 2021 of Illinois > 18 Soils and Foundations > 1807 Foundation Walls, Retaining Walls and Embedded Posts and Poles
Go To Full Code Chapter
1807.1 Foundation Walls
Foundation walls shall be designed and constructed in accordance with Sections 1807.1.1 through 1807.1.6. Foundation walls shall be supported by foundations designed in accordance with Section 1808.
1807.1.1 Design Lateral Soil Loads
Foundation walls shall be designed for the lateral soil loads set forth in Section 1610.
1807.1.2 Unbalanced Backfill Height
Unbalanced backfill height is the difference in height between the exterior finish ground level and the lower of the top of the concrete footing that supports the foundation wall or the interior finish ground level. Where an interior concrete slab on grade is provided and is in contact with the interior surface of the foundation wall, the unbalanced backfill height shall be permitted to be measured from the exterior finish ground level to the top of the interior concrete slab.
1807.1.3 Rubble Stone Foundation Walls
Foundation walls of rough or random rubble stone shall be not less than 16 inches (406 mm) thick. Rubble stone shall not be used for foundation walls of structures assigned to Seismic Design Category C, D, E or F.
1807.1.4 Permanent Wood Foundation Systems
Permanent wood foundation systems shall be designed and installed in accordance with AWC PWF. Lumber and plywood shall be preservative treated in accordance with AWPA U1 (Commodity Specification A, Special Requirement 4.2) and shall be identified in accordance with Section 2303.1.9.1.
1807.1.5 Concrete and Masonry Foundation Walls
Concrete and masonry foundation walls shall be designed in accordance with Chapter 19 or 21, as applicable.
Exception: Concrete and masonry foundation walls shall be permitted to be designed and constructed in accordance with Section 1807.1.6.
1807.1.6 Prescriptive Design of Concrete and Masonry Foundation Walls
Concrete and masonry foundation walls that are laterally supported at the top and bottom shall be permitted to be designed and constructed in accordance with this section.
1807.1.6.1 Foundation Wall Thickness
The thickness of prescriptively designed foundation walls shall be not less than the thickness of the wall supported, except that foundation walls of not less than 8-inch (203 mm) nominal width shall be permitted to support brick-veneered frame walls and 10-inch-wide (254 mm) cavity walls provided that the requirements of Section 1807.1.6.2 or 1807.1.6.3 are met.
1807.1.6.2 Concrete Foundation Walls
Concrete foundation walls shall comply with the following:
  1. The thickness shall comply with the requirements of Table 1807.1.6.2.
  2. The size and spacing of vertical reinforcement shown in Table 1807.1.6.2 are based on the use of reinforcement with a minimum yield strength of 60,000 pounds per square inch (psi) (414 MPa). Vertical reinforcement with a minimum yield strength of 40,000 psi (276 MPa) or 50,000 psi (345 MPa) shall be permitted, provided that the same size bar is used and the spacing shown in the table is reduced by multiplying the spacing by 0.67 or 0.83, respectively.
  3. Vertical reinforcement, where required, shall be placed nearest the inside face of the wall a distance, d, from the outside face (soil face) of the wall. The distance, d, is equal to the wall thickness, t, minus 1.25 inches (32 mm) plus one-half the bar diameter, db, [d = t - (1.25 + db / 2)]. The reinforcement shall be placed within a tolerance of ± 3/8 inch (9.5 mm) where d is less than or equal to 8 inches (203 mm) or ± 1/2 inch (12.7 mm) where d is greater than 8 inches (203 mm).
  4. In lieu of the reinforcement shown in Table 1807.1.6.2, smaller reinforcing bar sizes with closer spacings that provide an equivalent cross-sectional area of reinforcement per unit length shall be permitted.
  5. Concrete cover for reinforcement measured from the inside face of the wall shall be not less than 3/4 inch (19.1 mm). Concrete cover for reinforcement measured from the outside face of the wall shall be not less than 11/2 inches (38 mm) for No. 5 bars and smaller, and not less than 2 inches (51 mm) for larger bars.
  6. Concrete shall have a specified compressive strength, f 'c, of not less than 2,500 psi (17.2 MPa).
  7. The unfactored axial load per linear foot of wall shall not exceed 1.2 t f 'c where t is the specified wall thickness in inches.
TABLE 1807.1.6.2
CONCRETE FOUNDATION WALLSb, c
MAXIMUM WALL HEIGHT (feet) MAXIMUM UNBALANCED BACKFILL HEIGHTe (feet) MINIMUM VERTICAL REINFORCEMENT-BAR SIZE AND SPACING (inches)
Design lateral soil loada (psf per foot of depth)
30d 45d 60
Minimum wall thickness (inches)
7.5 9.5 11.5 7.5 9.5 11.5 7.5 9.5 11.5
5 4 PC PC PC PC PC PC PC PC PC
5 PC PC PC PC PC PC PC PC PC
6 4 PC PC PC PC PC PC PC PC PC
5 PC PC PC PC PC PC PC PC PC
6 PC PC PC PC PC PC PC PC PC
7 4 PC PC PC PC PC PC PC PC PC
5 PC PC PC PC PC PC PC PC PC
6 PC PC PC PC PC PC #5 at 48 PC PC
7 PC PC PC #5 at 46 PC PC #6 at 48 PC PC
8 4 PC PC PC PC PC PC PC PC PC
5 PC PC PC PC PC PC PC PC PC
6 PC PC PC PC PC PC #5 at 43 PC PC
7 PC PC PC #5 at 41 PC PC #6 at 43 PC PC
8 #5 at 47 PC PC #6 at 43 PC PC #6 at 32 #6 at 44 PC
9 4 PC PC PC PC PC PC PC PC PC
5 PC PC PC PC PC PC PC PC PC
6 PC PC PC PC PC PC #5 at 39 PC PC
7 PC PC PC #5 at 37 PC PC #6 at 38 #5 at 37 PC
8 #5 at 41 PC PC #6 at 38 #5 at 37 PC #7 at 39 #6 at 39 #4 at 48
9d #6 at 46 PC PC #7 at 41 #6 at 41 PC #7 at 31 #7 at 41 #6 at 39
10 4 PC PC PC PC PC PC PC PC PC
5 PC PC PC PC PC PC PC PC PC
6 PC PC PC PC PC PC #5 at 37 PC PC
7 PC PC PC #6 at 48 PC PC #6 at 35 #6 at 48 PC
8 #5 at 38 PC PC #7 at 47 #6 at 47 PC #7 at 35 #7 at 47 #6 at 45
9d #6 at 41 #4 at 48 PC #7 at 37 #7 at 48 #4 at 48 #6 at 22 #7 at 37 #7 at 47
10d #7 at 45 #6 at 45 PC #7 at 31 #7 at 40 #6 at 38 #6 at 22 #7 at 30 #7 at 38
For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound per square foot per foot = 0.157 kPa/m.
  1. For design lateral soil loads, see Section 1610.
  2. Provisions for this table are based on design and construction requirements specified in Section 1807.1.6.2.
  3. PC = Plain Concrete.
  4. Where unbalanced backfill height exceeds 8 feet and design lateral soil loads from Table 1610.1 are used, the requirements for 30 and 45 psf per foot of depth are not applicable (see Section 1610).
  5. For height of unbalanced backfill, see Section 1807.1.2.
1807.1.6.2.1 Seismic Requirements
Based on the seismic design category assigned to the structure in accordance with Section 1613, concrete foundation walls designed using Table 1807.1.6.2 shall be subject to the following limitations:
  1. Seismic Design Categories A and B. Not less than one No. 5 bar shall be provided around window, door and similar sized openings. The bar shall be anchored to develop fy in tension at the corners of openings.
  2. Seismic Design Categories C, D, E and F. Tables shall not be used except as allowed for plain concrete members in Section 1905.1.7.
Upcodes Diagrams
See More

Related Code Sections

Section 1807 Soils and Foundations, Foundation Walls, Retaining Walls and Embedded Posts and Poles
foundation divided by the net lateral force applied to the retaining wall. Exception: Where earthquake loads are included, the minimum safety factor ...
Building Code 2018 of Illinois > 18 Soils and Foundations > 1807 Foundation Walls, Retaining Walls and Embedded Posts and Poles
Section 1807 Soils and Foundations, Foundation Walls, Retaining Walls and Embedded Posts and Poles
as the available soil resistance at the base of the retaining wall foundation divided by the net lateral force ...
Building Code 2021 of Illinois > 18 Soils and Foundations > 1807 Foundation Walls, Retaining Walls and Embedded Posts and Poles
1807.1 Soils and Foundations, Foundation Walls
Foundation walls shall be designed and constructed in accordance with Sections 1807.1.1 through 1807.1.6. Foundation walls shall ...
Building Code 2021 of Illinois > 18 Soils and Foundations > 1807 Foundation Walls, Retaining Walls and Embedded Posts and Poles > 1807.1 Foundation Walls
1807.1.1 Soils and Foundations, Design Lateral Soil Loads
Foundation walls shall be designed for the lateral soil loads set forth in Section 1610 ...
Building Code 2021 of Illinois > 18 Soils and Foundations > 1807 Foundation Walls, Retaining Walls and Embedded Posts and Poles > 1807.1 Foundation Walls > 1807.1.1 Design Lateral Soil Loads
1807.1.1 Soils and Foundations, Design Lateral Soil Loads
Foundation walls shall be designed for the lateral soil loads set forth in Section 1610 ...
Building Code 2018 of Illinois > 18 Soils and Foundations > 1807 Foundation Walls, Retaining Walls and Embedded Posts and Poles > 1807.1 Foundation Walls > 1807.1.1 Design Lateral Soil Loads