15A-3-108. Amendments to Chapters 17 through 19 of IBC.

1,291 words·~6 min read·/ut/title-15a/chapter-3/15a-3-108

A research copy — for the controlling text, always check the official state or federal source. Not legal advice.

Effective 3/17/2026

(1)A new IBC, Section 1807.1.6.4, is added as follows:

"1807.1.6.4 Empirical concrete foundation design. Group R, Division 3 Occupancies three stories or less in height, and Group U Occupancies, which are constructed in accordance with Section 2308, or with other methods employing repetitive wood-frame construction or repetitive cold-formed steel structural member construction, shall be permitted to have concrete foundations constructed in accordance with Table 1807.1.6.4."

(2)A new IBC, Table 1807.1.6.4 is added as follows:

"TABLE 1807.1.6.4

EMPIRICAL FOUNDATION WALLS (1,7,8)

Max. Height Top Edge Support Min.

Thickn ess Vertic al Steel

(2)Horizon tal Steel

(3)Steel at

Openings

(4)Max. Lintel Length Min. Lintel Length

2'(610 mm) None 6"

(5)2- #4 Bars 2- #4 Bars above

1- #4 Bar each side

1- #4 Bar below 2'(610 mm) 2" for each foot of opening width;

min. 6"

3'(914 mm) None 6" #4@3 2" 3- #4 Bars 2- #4 Bars above

1- #4 Bar each side

1- #4 Bar below 2'(610 mm) 2" for each foot of opening width;

min. 6"

4'(1,219 mm) None 6" #4@3 2" 4- #4 Bars 2- #4 Bars above

1- #4 Bar each side

1- #4 Bar below 3'(914 mm) 2" for each foot of opening width;

min. 6"

6'(1,829 mm) Floor or roof Diaphra gm

(6)8" #4@2 4" 5- #4 Bars 2- #4 Bars above

1- #4 Bar each side

1- #4 Bar below 6'(1,829 mm) 2" for each foot of opening width;

min. 6"

8'(2,438 mm) Floor or roof Diaphra gm

(6)8" #4@2 4" 6- #4 Bars 2- #4 Bars above

1- #4 Bar each side

1- #4 Bar below 6'(1,829 mm) 2" for each foot of opening width;

min. 6"

9'(2,743 mm) Floor or roof Diaphra gm

(6)8" #4@1 6" 7- #4 Bars 2- #4 Bars above

1- #4 Bar each side

1- #4 Bar below 6'(1,829 mm) 2" for each foot of opening width;

min. 6"

Over 9'(2,743 mm), Engineering required for each column

Footnotes:

(1)Based on 3,000 psi (20.6 Mpa) concrete and 60,000 psi (414 Mpa) reinforcing steel.

(2)To be placed in the center of the wall, and extended from the footing to within three inches (76 mm) of the top of the wall; dowels of #4 bars to match vertical steel placement shall be provided in the footing, extending 24 inches (610 mm) into the foundation wall.

(3)One bar shall be located in the top four inches (102 mm), one bar in the bottom four inches (102 mm) and the other bars equally spaced between. Such bar placement satisfies the requirements of Section 1808.8.6. Corner reinforcing shall be provided so as to lap 24 inches (610 mm).

(4)Bars shall be placed within two inches (51 mm) of the openings and extend 24 inches (610 mm) beyond the edge of the opening; vertical bars may terminate three inches (76 mm) from the top of the concrete.

(5)Dowels of #4 bar at 32 inches on center shall be provided in the footing, extending 18 inches (457 mm) into the foundation wall.

(6)Diaphragm shall conform to the requirements of Section 2308.

(7)Footing shall be a minimum of nine inches thick by 20 inches wide.

(8)Soil backfill shall be soil classification types GW, GP, SW, or SP, per Table 1610.1. Soil shall not be submerged or saturated in groundwater."

(3)A new Section 1904.3, is added as follows:

"1904.3 ACI 318, Section 19.3.1.1." Modify ACI 318, Table 19.3.1.1 to read as follows: In the portion of the table designated as "Conditions", the following Exposure category and class is deleted and replaced with the following:

"F0: Concrete elements not exposed to freezing and thawing cycles including footing elements, such as footings, tie beams, piles, and pile caps, etc., that are completely buried in soil."

(4)A new IBC, Section 1905.8, is added as follows:

"1905.8 In ACI 318, Section 18.10.3 is deleted and replaced with the following:

18.10.3 Design Forces:

18.10.3.1 Design shear forces for horizontal wall segments, including coupling beams, shall be in accordance with 18.10.7.

18.10.3.2 Design shear forces for wall piers shall be in accordance with 18.10.8.

18.10.3.3 Design shear forces for parts of walls not covered by 18.10.3.1 or 18.10.3.2 shall be in accordance with the requirements of 18.10.3.3.1 through 18.10.3.3.5.

18.10.3.3.1 If the wall design actions are determined in accordance with nonlinear dynamic analysis procedures satisfying Appendix A, design forces shall be as determined in Appendix A.

18.10.3.3.2 If the design shear force is determined by linear analysis procedures of the general building code, it shall be amplified by the product v v, where v and v, are defined in 18.10.3.3.3 through 18.10.3.3.5.

18.10.3.3.3 v and v, shall be in accordance with Table 18.10.3.3.3. Alternatively, it shall be permitted to calculate v = Mpr/Mu at the critical section for flexure, where Mpr is calculated for axial force that includes the effects of and the expected gravity loads, with expected gravity loads in accordance with ASCE/SEI 7 Section 16.3.2.

Table 18.10.3.3.3 Factors v and v

Condition v v

hwcs/lw≤1.0 1.0 1.0

1.0 < hwcs/lw < 2.0 Linear interpolation permitted between 1.0 and 1.5 1.0

hwcs/lw ≥ 2.0 1.5 0.8 + 0.09hn1/3 1.0

18.10.3.3.4 If the general building code includes provision to account for over strength of the seismic-force-resisting system, it shall be permitted to take v v equal to o.

18.10.3.3.5 If 3 v v = o, it shall be permitted to take the redundancy factor contained in the general building code equal to 1.0 for determination of the design shear force."

(5)A new IBC, Section 1905.9, is added as follows:

"1905.9 In ACI 318, Section 21.2.4.1, the following words are added after the words "resist E", except for walls where v ≥1.5 or if v is taken as equal to o."

(6)A new IBC, Section 1909, Modifications to ACI 318, is added as follows:

"1909.1 General. The text of ACI 318 shall be modified as indicated in Sections 1909.2 through 1909.5.

1909.2 ACI 318 Section 13.2.6.2, For shallow foundation members continuously supported by soil and designed based upon the assumption of rigid behavior of the shallow member,

(a)and

(b)shall be permitted:

(a)For one-way shear strength, Vc shall be taken as: Vc = 2flcbwd.

(b)For two-way shear strength, the size factor, s, specified in 22.6 shall be taken equal to 1.0.

1909.3 ACI 318, Section 13.3.6.1.1 is added as follows:

13.3.6.1.1 It shall be permitted to calculate Vc for cantilever retaining wall as Vc =2flcbwd.

1909.4 ACI 318, Section 13.3.7 Basement Walls is added as follows:

13.3.7.1 The design of basement walls to resist out-of-plane lateral earth pressures shall satisfy

(a)through (e):

(a)Basement walls shall be designed as one-way slabs in accordance with the applicable provision of Chapter 7 or as two-way slabs in accordance with the applicable provision of Chapter 8.

(b)Basement walls shall be designed to resist hydrostatic pressure, if applicable.

(c)It shall be permitted to calculate the one-way sheer strength of concrete as Vc = 2flcbwd.

(d)For two-way shear strength, the size effect factor s, as specified in 22.6 shall be taken equal to 1.0.

(e)Basement walls shall satisfy the applicable provision of Chapter 18.13.3.7.2. For loads other than out-of-plane lateral earth pressure, basement walls shall satisfy the applicable provisions of Chapter 11."

(7)1909.5 ACI 318, Section 22.5.5.1.1, is deleted and replaced with the following:

"22.5.5.1.1 Vc shall not be taken as greater than 5flcbwd. Vc need not be taken less than flcbwd except in cases

(a)or (b):

(a)elements subject to net axial tension

(b)if Sections 18.6.5.2 or 18.7.6.2.1 apply."

Amended by Chapter 47 , 2026 General Session