Section 516C — POINTING OF UNREINFORCED MASONRY WALLS
516C.4 Packing.
San Francisco Building Inspection Commission Codes · 2022 edition · ingested 2026-07-08 · San Francisco
516C.4 Packing. The joint into which the mortar is to be packed shall be damp but without freestanding water. The mortar shall be tightly packed into the joint in layers not exceeding ¼ inch (6.35 mm) in depth until it is filled; then it shall be tooled to a smooth surface to match the original profile.
FIGURE 5C-1 – ACCEPTABLE DIAPHRAGM SPAN
NOTE: To convert feet to meters, multiply by 0.3048.
FIGURE 5C-2 – ANALYSIS OF UNREINFORCED MASONRY WALL IN-PLANE SHEAR FORCES
TABLE 5C-A – ELEMENTS REGULATED BY THIS CHAPTER
| ELEMENTS | SECTION | PROCEDURE |
|---|---|---|
| ELEMENTS | SECTION | |
| Col1 | Col2 | BOLTS- PLUS |
| --- | --- | --- |
| ELEMENTS | SECTION | PROCEDURE |
| ELEMENTS | SECTION | BOLTS- PLUS |
| Masonry Shear Strength | 506C.3.3 | X |
| Diaphragms | 510C.1 | |
| Diaphragms | 511C.4 | |
| Diaphragms | 304.4 | |
| Diaphragm Shear Transfer | 510C.1 | X1 |
| Diaphragm Shear Transfer | 511C.5 | X1 |
| Diaphragm Shear Transfer | 513C.2 | X |
| Chords | 511C.4 | |
| Diaphragm Capacity Ratios | SFBC 1604 | |
| Collectors | 513C.3 | |
| Collectors | 513C.4 | |
| Collectors | 304.4 | |
| Analysis of Vertical Elements | 512C | |
| Crosswalls | 511C.3 | |
| Shear Walls | 510C.3 | |
| Shear Walls | 511C.6 | |
| Shear Walls | 304.4 | |
| Out of Plane Wall Anchorage | 513C.1 | X |
| Out of Plane Wall Anchorage | 304.4 | |
| Ties & Continuity | 513C.4 | |
| Ties & Continuity | 304.4 | |
| Wall Bracing | 513C.5 | X |
| Parapets | 513C.6 | X |
| Veneer | 513C.7 | X |
| --- | --- | --- |
| Nonstructural Masonry Walls | 513C.8 | |
| Truss & Beam Supports | 513C.9 | |
| Adjacent Buildings | 513C.10 | |
| Subdiaphragms | 304.4 | |
| Subdiaphragms | SFBC 1604.8.2 | |
| Subdiaphragms | ASCE 7-16 Section 12.11.24 |
|
| 1 Diaphragm shear transfer forces shall be calculated using the General Procedures unless the building qualifies for the use of the Special Procedure. |
1 Diaphragm shear transfer forces shall be calculated using the General Procedures unless the building qualifies for the use of the Special Procedure. |
1 Diaphragm shear transfer forces shall be calculated using the General Procedures unless the building qualifies for the use of the Special Procedure. |
| 2 Retrofit procedure per SFEBC Section 304.4. | 2 Retrofit procedure per SFEBC Section 304.4. | 2 Retrofit procedure per SFEBC Section 304.4. |
| 3 Wood shear walls allowed only for one- or two-story building per San Francisco Building Code Section 2305.1. |
3 Wood shear walls allowed only for one- or two-story building per San Francisco Building Code Section 2305.1. |
3 Wood shear walls allowed only for one- or two-story building per San Francisco Building Code Section 2305.1. |
| 4 Only in-plane shear check required. (Rocking not allowed.) | 4 Only in-plane shear check required. (Rocking not allowed.) | 4 Only in-plane shear check required. (Rocking not allowed.) |
| 5 Use (h/t) for “All other walls” from Table 5C-B. | 5 Use (h/t) for “All other walls” from Table 5C-B. | 5 Use (h/t) for “All other walls” from Table 5C-B. |
TABLE 5C-B – ALLOWABLE VALUE OF HEIGHT-TO-THICKNESS RATIO OF UNREINFORCED MASONRY WALLS
| WALL TYPES | BUILDINGS WITH 1 CROSSWALLS |
ALL OTHER BUILDINGS |
|---|---|---|
| Walls of one-story buildings | 162,3 | 13 |
| First story wall of multistory buildings |
16 | 15 |
| Walls in top story of multistory buildings |
142,3 | 9 |
| All other walls | 16 | 13 |
| 1 Applies to the Special Procedure of Section 511C and the Bolts-plus Procedure of the last paragraph of Exception 1 to Section 509C.2 only. See Section 511C.7 for other restrictions. |
1 Applies to the Special Procedure of Section 511C and the Bolts-plus Procedure of the last paragraph of Exception 1 to Section 509C.2 only. See Section 511C.7 for other restrictions. |
1 Applies to the Special Procedure of Section 511C and the Bolts-plus Procedure of the last paragraph of Exception 1 to Section 509C.2 only. See Section 511C.7 for other restrictions. |
| 2 This value of height-to-thickness ratio may be used only where mortar shear tests establish a tested mortar shear strength, vt, of not less than 100 psi (689.48 kPa). This value may also be used where the tested mortar strength is not less than 60 psi (413.69 kPa) and a visual examination of the collar joint indicates not less than 50 percent mortar coverage. |
2 This value of height-to-thickness ratio may be used only where mortar shear tests establish a tested mortar shear strength, vt, of not less than 100 psi (689.48 kPa). This value may also be used where the tested mortar strength is not less than 60 psi (413.69 kPa) and a visual examination of the collar joint indicates not less than 50 percent mortar coverage. |
2 This value of height-to-thickness ratio may be used only where mortar shear tests establish a tested mortar shear strength, vt, of not less than 100 psi (689.48 kPa). This value may also be used where the tested mortar strength is not less than 60 psi (413.69 kPa) and a visual examination of the collar joint indicates not less than 50 percent mortar coverage. |
3 Where a visual examination of the collar joint indicates not less than 50 percent mortar coverage, and the tested mortar shear strength, vt, is greater than 30 psi (206.84 kPa) but less than 60 psi (413.69 kPa), the allowable height-to-thickness ratio may be determined by linear interpolation between the larger and smaller ratios in direct proportion to the tested mortar strength.
TABLE 5C-C – HORIZONTAL FORCE FACTOR, Cp [1]
| CONFIGURATION OF MATERIALS | C p |
|---|---|
| Roofs with straight or diagonal sheathing and roofing applied directly to the sheathing, or floors with straight tongue-and-groove sheathing |
0.50 |
| Diaphragms with double or multiple layers of boards with edges offset, and blocked plywood systems |
0.75 |
| 1 Applicable to the Special Procedure of Section 511C only. | 1 Applicable to the Special Procedure of Section 511C only. |
TABLE 5C-D – ALLOWABLE VALUES FOR EXISTING MATERIALS
| EXISTING MATERIALS OR CONFIGURATION OF 1 MATERIALS |
ALLOWABLE VALUES |
|---|---|
| 1. HORIZONTAL DIAPHRAGMS2 | (x 14.5939 for N/m) |
| a. Roofs with straight sheathing and roofing applied directly to the sheathing |
100 pounds per foot seismic shear |
| b. Roofs with diagonal sheathing and roofing applied directly to the sheathing |
250 pounds per foot seismic shear |
| c. Floors with straight tongue-and-groove sheathing | 100 pounds per foot seismic shear |
| d. Floors with straight sheathing and finished wood flooring with board edges offset or perpendicular |
500 pounds per foot seismic shear |
| e. Floors with diagonal sheathing and finished wood flooring |
600 pounds per foot seismic shear |
| 2. CROSSWALLS2,3 | (x 14.5939 for N/m) |
| a. Plaster on wood or metal lath | per side: 200 pounds per foot seismic shear |
| b. Plaster on gypsum lath | 175 pounds per foot seismic shear |
| c. Gypsum wallboard, unblocked edges | 75 pounds per foot seismic shear |
| --- | --- |
| d. Gypsum wallboard, blocked edges | 125 pounds per foot seismic shear |
| 3. EXISTING FOOTINGS, WOOD FRAMING, STRUCTURAL STEEL AND REINFORCE STEEL |
(x 6.895 for kPa) |
| a. Plain concrete footings | f ´c = 1,500 psi unless otherwise shown by tests4 |
| b. Douglas fir wood | Allowable stress same as D.F. No. 14 |
| c. Reinforcing steel | ft = 18,000 psi maximum4 |
| d. Structural steel | ft = 20,000 psi maximum4 |
| 1 Material must be sound and in good condition. | 1 Material must be sound and in good condition. |
| 2 A one-third increase in allowable stress is not allowed | 2 A one-third increase in allowable stress is not allowed |
| 3 Shear values of these materials may be combined, except the total combined value shall not exceed 300 pounds per foot (2068.43 kPa). |
3 Shear values of these materials may be combined, except the total combined value shall not exceed 300 pounds per foot (2068.43 kPa). |
| 4 Stresses given may be increased for combinations of loads as specified in this code | 4 Stresses given may be increased for combinations of loads as specified in this code |
TABLE 5C-E – ALLOWABLE VALUES OF NEW MATERIALS USED IN CONJUNCTION WITH EXISTING CONSTRUCTION
| NEW MATERIALS OR CONFIGURATIONS OF MATERIALS |
1 ALLOWABLE VALUES |
|---|---|
| 1. HORIZONTAL DIAPHRAGMS10 | (x 14.5939 for N/m) |
| a. Plywood sheathing nailed directly over existing straight sheathing with ends of plywood sheets bearing on joists or rafters and edges of plywood located on center of individual sheathing boards |
225 pounds per foot seismic shear |
| b. Plywood sheathing nailed directly over existing diagonal sheathing with ends of plywood sheets bearing on joists or rafters |
375 pounds per foot seismic shear |
| c. Plywood sheathing nailed directly over existing straight or diagonal sheathing with ends of plywood sheets bearing on joists or rafters with edges of plywood located over new blocking and nailed to provide a minimum nail penetration into framing and blocking of 1 5/8 inches (41.28 mm) |
75 percent of the values specified in San Francisco Building Code Table 2306.2.1(1) |
| 2. SHEAR WALLS: (GENERAL PROCEDURE) | Col2 |
| --- | --- |
| Plywood sheathing applied directly over wood studs. No value shall be given to plywood applied over existing plaster or wood sheathing. |
100 percent of the value specified in San Francisco Building Code Table 2306.2.1(2) for shear walls |
| 3. CROSSWALLS: (SPECIAL PROCEDURE) | |
| a. Plywood sheathing applied directly over wood studs. No value shall be given to plywood applied over existing plaster or wood sheathing |
133 percent of the value specified in San Francisco Building Code Table 2306.2.1(2) for shear walls |
| b. Drywall or plaster applied directly over wood studs | 100 percent of the values in San Francisco Building Code Table 2306.3(3) |
| c. Drywall or plaster applied to sheathing over existing wood studs |
The values in San Francisco Building Code Table 2306.3(3) reduced as noted in Footnote a of that table2 |
| 4. TENSION BOLTS | (x 4.448 for N) |
| a. Bolts extending entirely through unreinforced masonry walls secured with bearing plates on far side of a 3 wythe minimum wall with at least 30 square inches (19,355 mm2) of area3,4,11 |
1,800 pounds per bolt8 |
| a. Bolts extending entirely through unreinforced masonry walls secured with bearing plates on far side of a 3 wythe minimum wall with at least 30 square inches (19,355 mm2) of area3,4,11 |
900 pounds per bolt for 2 wythe walls8 |
| b. Bolts extending to the exterior face of the wall with a 2½-inch (63.5 mm) round plate under the head and drilled at an angle of 22½ degrees to the horizontal, installed as specified for shear bolts3,4,5 |
1,200 pounds per bolt |
| 5. SHEAR BOLTS | |
| Bolts embedded a minimum of 8 inches into unreinforced masonry walls and centered in a 2½-inch diameter hole filled with dry-pack or non-shrink grout. Through bolts with first 8 inches as noted above and embedded bolts as noted in item 4b.4,5,9 |
½ inch dia. = 350 pounds7,8 |
| Bolts embedded a minimum of 8 inches into unreinforced masonry walls and centered in a 2½-inch diameter hole filled with dry-pack or non-shrink grout. Through bolts with first 8 inches as noted above and embedded bolts as noted in item 4b.4,5,9 |
5/8 inch dia. = 500 pounds7,8 |
| Bolts embedded a minimum of 8 inches into unreinforced masonry walls and centered in a 2½-inch diameter hole filled with dry-pack or non-shrink grout. Through bolts with first 8 inches as noted above and embedded bolts as noted in item 4b.4,5,9 |
¾ inch dia. = 750 pounds7,8 |
| 6. INFILLED WALLS | |
| Reinforced masonry infilled openings in existing unreinforced masonry walls. Provide keys or dowels to match reinforcing. |
Same values as for unreinforced masonry walls |
| 7. REINFORCED MASONRY | |
| Masonry piers and walls reinforced per San Francisco Building Code Chapter 21 |
Same values as specified in San Francisco 6 Building Code Section 2107 |
| --- | --- |
| 8. REINFORCED CONCRETE | |
| Concrete footings, walls and piers reinforced as specified in San Francisco Building Code Chapter 19 and designed for tributary loads |
Same values as specified in San Francisco Building Code Chapter 196 |
| 1 A one-third increase in allowable stress is not allowed, except as noted. | 1 A one-third increase in allowable stress is not allowed, except as noted. |
| 2 In addition to existing sheathing value. | 2 In addition to existing sheathing value. |
| 3 Bolts to be ½ inch (1.27 mm) minimum in diameter. | 3 Bolts to be ½ inch (1.27 mm) minimum in diameter. |
| 4 Drilling for bolts and dowels shall be done with an electric rotary drill. Impact tools shall not be used for drilling holes or tightening anchors and shear bolt nuts. |
4 Drilling for bolts and dowels shall be done with an electric rotary drill. Impact tools shall not be used for drilling holes or tightening anchors and shear bolt nuts. |
| 5 Embedded bolts to be tested as specified in Section 507C. | 5 Embedded bolts to be tested as specified in Section 507C. |
| 6 Stress given may be increased for combinations of load as specified in this code. | 6 Stress given may be increased for combinations of load as specified in this code. |
| 7 A one-third increase in allowable stress is allowed for short-term loading. | 7 A one-third increase in allowable stress is allowed for short-term loading. |
| 8 Other bolt sizes, values and installation methods may be used, provided a testing program is conducted in accordance with Section 515C. Bolt spacing shall not exceed 6 feet (1.83 m) on center and shall not be less than 12 inches (0.305 m) on center. |
8 Other bolt sizes, values and installation methods may be used, provided a testing program is conducted in accordance with Section 515C. Bolt spacing shall not exceed 6 feet (1.83 m) on center and shall not be less than 12 inches (0.305 m) on center. |
| 9 Tension and shear from seismic loads need not be assumed to act simultaneously. | 9 Tension and shear from seismic loads need not be assumed to act simultaneously. |
| NEW MATERIALS OR CONFIGURATIONS OF MATERIALS |
1 ALLOWABLE VALUES |
|---|---|
| 10 Values and limitations are for nailed plywood. Higher values may be used for other approved fastening systems such as staples when approved by the Building Official. |
10 Values and limitations are for nailed plywood. Higher values may be used for other approved fastening systems such as staples when approved by the Building Official. |
| 11 Plate size may be reduced to not less than 9 square inches (5805 mm2), provided the bearing stress on the masonry at design load does not exceed 60 pounds per square inch, psi (414 kPa). |
11 Plate size may be reduced to not less than 9 square inches (5805 mm2), provided the bearing stress on the masonry at design load does not exceed 60 pounds per square inch, psi (414 kPa). |
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