Section C104 — RETROFITTING GABLE END WALLS TO ENHANCE WIND RESISTANCE

[BS] C104.1 General. These prescriptive methods of retrofitting are intended to increase the resistance of existing gable end

                                                                                    construction for out-of-plane wind loads resulting from high-wind events. The ceiling diaphragm shall be comprised of minimum [1] / 2

inch-thick (12.7 mm) gypsum board, minimum nominal [3] / 8 -inch-thick (9.5 mm) wood structural panels, or plaster. An overview isometric drawing of one type of gable end retrofit to improve wind resistance is shown in Figure C104.1.

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APPENDIX C—GUIDELINES FOR THE WIND RETROFIT OF EXISTING BUILDINGS

[BS] FIGURE C104.1—BASIC GABLE END RETROFIT METHODOLOGY

[BS] C104.2 Horizontal braces. Horizontal braces shall be installed perpendicular to the roof and ceiling framing members at the location of each existing gable end stud greater than 3 feet (91 cm) in length. Unless it is adjacent to an omitted horizontal brace location, horizontal braces shall be minimum 2-inch by 4-inch (38 mm by 89 mm) dimensional lumber as defined in Section C103.3. A single horizontal brace is required at the top and bottom of each gable end stud for Retrofit Configuration A, B, or C. Two horizontal braces are required at the top and bottom of each gable end stud for Retrofit Configuration D. Maximum heights of gable end wall studs and associated retrofit studs for each Retrofit Configuration shall not exceed the values listed in Table C104.2. Horizontal braces shall be oriented with their wide faces across the roof or ceiling framing members, be fastened to not fewer than three framing members, and extend not less than 6 feet (183 cm) measured perpendicularly from the gable end plus 2 [1] / 2 inches (64 mm) beyond the last top chord or bottom chord member (rafter or ceiling joist) from the gable end as shown in Figures C104.2(1), C104.2(2), C104.2(3) and C104.2(4).

ented with their wide faces across the roof or ceiling framing members, be fastened to not fewer than three framing members, and extend not less than 6 feet (183 cm) measured perpendicularly from the gable end plus 2 [1] / 2 inches (64 mm) beyond the last top chord or bottom chord member (rafter or ceiling joist) from the gable end as shown in Figures C104.2(1), C104.2(2), C104.2(3) and C104.2(4).

[BS] TABLE C104.2—STUD LENGTH LIMITATIONS BASED ON EXPOSURE AND DESIGN WIND SPEED

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APPENDIX C—GUIDELINES FOR THE WIND RETROFIT OF EXISTING BUILDINGS

[BS] FIGURE C104.2(1)TRUSS FRAMED GABLE END

ELEVATION VIEW

MINIMUM THICKNESS 20 GAUGE FASTENED WITH MINIMUM 9 EACH 1 MINIMUM THICKNESS 18 GAUGE FASTENED WITH MINIMUM 12 EACH 1 MINIMUM THICKNESS 18 GAUGE FASTENED WITH MINIMUM 8 EACH 1 MINIMUM THICKNESS 20 GAUGE FASTENED WITH MINIMUM 6 EACH 1 [1][1][1] /// [1] 444 / ″″″ 4 FASTENERS AT EACH END FOR RETROFIT CONFIGURATION A FASTENERS AT EACH END FOR RETROFIT CONFIGURATION B FASTENERS AT EACH END OF EACH STRAP FOR RETROFIT CONFIGURATION D ″ FASTENERS AT EACH END FOR RETROFIT CONFIGURATION C

HORIZONTAL BRACE, MINIMUM 2X4 SECURED TO EACH ATTIC FRAMING MEMBER WITH 3 EACH 3 ″ FASTENERS

ATTIC FRAMING MEMBERS

EXISTING STUD OF TRUSS FLAT AGAINST GABLE END WALL

FASTENERS SHALL NOT BE PLACED CLOSER TO ENDS OF LUMBER THAN 2FASTENERS SHALL NOT BE PLACED CLOSER TO EDGES OF LUMBER THAN [1][1] // 22 ″.″ EXCEPT WHERE STRAPS DICTATE OTHERWISE. THE NUMBER OF FASTENERS SHOWN IS NOT NECESSARILY THE NUMBER REQUIRED.

PLAN VIEWS

RETROFIT CONFIGURATIONS A, B AND C

For SI: 1 inch = 25.4 mm.

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APPENDIX C—GUIDELINES FOR THE WIND RETROFIT OF EXISTING BUILDINGS

[BS] FIGURE C104.2(2)—CONVENTIONALLY FRAMED GABLE END L-BENT STRAP

For SI: 1 inch = 25.4 mm.

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APPENDIX C—GUIDELINES FOR THE WIND RETROFIT OF EXISTING BUILDINGS

[BS] FIGURE C104.2(3)—TRUSS FRAMED GABLE END U-BENT STRAP

For SI: 1 inch = 25.4 mm.

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APPENDIX C—GUIDELINES FOR THE WIND RETROFIT OF EXISTING BUILDINGS

[BS] FIGURE C104.2(4)—CONVENTIONALLY FRAMED GABLE END U-BENT STRAP

For SI: 1 inch = 25.4 mm.

[BS] C104.2.1 Existing gable end studs. If the spacing of existing vertical gable end studs is greater than 24 inches (64 mm), a new stud and corresponding horizontal braces shall be installed such that the maximum spacing between existing and added studs shall be not greater than 24 inches (64 mm). Additional gable end wall studs shall not be required at locations where their length would be 3 feet (914 mm) or less. Each end of each required new stud shall be attached to the existing roofing framing members (truss top chord or rafter and truss bottom chord or ceiling joist) using not fewer than two 3-inch (76 mm) toenail fasteners (#8 wood screws or 10d nails) and a metal connector with minimum uplift capacity of 175 pounds (778 N), or nail plates with not fewer than four 1 [1] / 4 -inch-long (32 mm) fasteners (No. 8 wood screws or 8d nails).

shall be attached to the existing roofing framing members (truss top chord or rafter and truss bottom chord or ceiling joist) using not fewer than two 3-inch (76 mm) toenail fasteners (#8 wood screws or 10d nails) and a metal connector with minimum uplift capacity of 175 pounds (778 N), or nail plates with not fewer than four 1 [1] / 4 -inch-long (32 mm) fasteners (No. 8 wood screws or 8d nails).

[BS] C104.2.2 Main method of installation. Each horizontal brace shall be fastened to each existing roof or ceiling member that it crosses using three 3-inch-long (76 mm) fasteners (No. 8 wood screws or 10d nails) as indicated in Figure C104.2(1) and Figure C104.2(3) for trusses and Figure C104.2(2) and Figure C104.2(4) for conventionally framed gable end walls. Alternative methods for providing horizontal bracing of the gable end studs as provided in Sections C104.2.3 through C104.2.9 shall be permitted.

[BS] C104.2.3 Omitted horizontal brace. Where conditions exist that prevent installation in accordance with Section C104.2.2, horizontal braces shall be permitted to be omitted for height limitations corresponding to Retrofit Configurations A and B as defined in Table C104.2 provided that installation is as indicated in Figure C104.2.3 and provided that all of the following conditions are met. This method is not permitted for Retrofit Configurations C or D.

1. There shall be not fewer than two horizontal braces on each side of an omitted horizontal brace or not fewer than one horizontal brace if it is the end horizontal brace. Omitted horizontal braces must be separated by not fewer than two horizontal braces even if that location is composed of two retrofit studs and two horizontal braces.
2. Horizontal braces adjacent to the omitted horizontal brace shall be 2-inch by 6-inch (38 mm by 140 mm) lumber, shall butt against the existing studs, and shall be fastened to each existing roof or ceiling member crossed using three 3-inchlong (76 mm) fasteners (No. 8 wood screws or 10d nails). For Retrofit Configuration B, four fasteners shall be required on not fewer than one of the connections between the horizontal brace and the existing roof and ceiling framing members. Fasteners shall be spaced a not less than [3] / 4 inch (19.1 mm) from the edges of the horizontal braces and not less than 1 [3] / 4 inches (44 mm) from adjacent fasteners.
3. Where the existing studs on each side of an omitted horizontal brace have their wide face perpendicular to the gable end wall, the retrofit studs at those locations and the retrofit stud at the omitted horizontal brace locations shall extend not

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APPENDIX C—GUIDELINES FOR THE WIND RETROFIT OF EXISTING BUILDINGS

less than 3 [3] / 4 inches (95 mm) beyond the interior edge of the existing studs for both Retrofit Configurations A and B. The edges of the three retrofit studs facing towards the interior of the attic shall be aligned such that they are the same distance from the gable end wall. 4. Retrofit studs shall be fastened to existing studs in accordance with Section C104.3. 5. Retrofit studs adjacent to the omitted horizontal brace shall be fastened to the horizontal brace using straps in accordance with Table C104.4.1 consistent with the size of the retrofit stud. The method applicable to Table C104.4.2 is not permitted. 6. A strong back made of minimum of 2-inch by 8-inch (38 mm by 184 mm) nominal lumber shall be placed parallel to the gable end and shall be located on and span between horizontal braces on the two sides of the omitted horizontal brace and shall extend beyond each horizontal brace by not less than 2 [1] / 2 inches (64 mm). The strong back shall be butted to the three retrofit studs. The strong back shall be attached to each of the horizontal braces on which it rests with five 3inch-long (76 mm) fasteners (#8 screws or 8d nails). The fasteners shall have a minimum [3] / 4 -inch (19.1 mm) edge distance and a minimum 2 [1] / 2 -inch (64 mm) spacing between fasteners. Additional compression blocks shall not be required at locations where a strong back butts against a retrofit stud. 7. The retrofit stud at the location of the omitted horizontal braces shall be fastened to the strong back using a connector with minimum uplift capacity of 800 pounds (3559 N) and installed such that this capacity is oriented in the direction perpendicular to the gable end wall. 8. The use of shortened horizontal braces using the alternative method of Section C104.2.5 is not permitted for horizontal braces adjacent to the omitted horizontal braces. 9. Horizontal braces shall be permitted to be interrupted in accordance with Section C104.2.8.

[BS] FIGURE C104.2.3—OMITTED HORIZONTAL BRACE

For SI: 1 inch = 25.4 mm.

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APPENDIX C—GUIDELINES FOR THE WIND RETROFIT OF EXISTING BUILDINGS

[BS] C104.2.4 Omitted horizontal brace and retrofit stud. Where conditions exist that prevent installation in accordance with Section C104.2.2 or C104.2.3, then retrofit studs and horizontal braces shall be permitted to be omitted from those locations by installation of ladder assemblies for Retrofit Configurations A and B as defined in Table C104.2 provided that all of the following conditions are met. This method is not permitted for Retrofit Configurations C or D.

1. Not more than two ladder assemblies are permitted on a single gable end.

104.2.3, then retrofit studs and horizontal braces shall be permitted to be omitted from those locations by installation of ladder assemblies for Retrofit Configurations A and B as defined in Table C104.2 provided that all of the following conditions are met. This method is not permitted for Retrofit Configurations C or D.

1. Not more than two ladder assemblies are permitted on a single gable end.

2. There shall be not fewer than two retrofit studs and horizontal brace assemblies on either side of the locations where the retrofit studs and horizontal bracing members are omitted (two ladder braces shall not bear on a single retrofit stud).

3. Where the existing studs on each side of an omitted horizontal brace have their wide face parallel to the gable end wall the retrofit studs at those locations and the retrofit stud at the omitted horizontal brace locations shall be 2-inch by 6inch (38 mm by 180 mm) nominal lumber for Retrofit Configuration A and 2-inch by 8-inch (38 mm by 184 mm) lumber for Retrofit Configuration B.

4. Horizontal braces adjacent to the omitted horizontal brace shall be 2-inch by 6-inch (38 mm by 180 mm) nominal lumber and be fastened to each existing roof or ceiling member crossed using three 3-inch long (76 mm) fasteners (#8 wood screws or 10d nails) as indicated in Figures C104.2(1) and C104.2(3) for gable end frames and Figures C104.2(2) and C104.2(4) for conventionally framed gable end walls. For Retrofit Configuration B, four fasteners shall be required on one of the connections between the horizontal brace and the existing roof and ceiling framing members.

5. Ladder rungs shall be provided across the location of the omitted retrofit studs as indicated in Figure C104.2.4(1) for gable end frames and Figure C104.2.4(2) for conventionally framed gable end walls.

6. Ladder rungs shall be minimum 2-inch by 4-inch (38 mm by 89 mm) lumber oriented with their wide face horizontal and spaced not greater than 16 inches (406 mm) on center vertically.

7. Where ladder rungs cross wall framing members they shall be connected to the wall framing members with a metal connector with a minimum capacity of 175 pounds (778 N) in the direction perpendicular to the gable end wall.

8. Notching of the ladder rungs shall not be permitted unless the net depth of the framing member is not less than 3 [1] / 2 inches (89 mm).

[BS] FIGURE C104.2.4(1)—LADDER BRACING FOR OMITTED RETROFIT STUD (GABLE END FRAME)

EXISTING TRUSS

GABLE END WALL

REQUIRED 2x RETROFIT STUD

HURRICANE TIE (MIN. 175 LB. CAPACITY)
FASTENERS (TYP) FROM EXISTING GABL
L LADDER BLOCKING WHEN ANY EXISTING
ARE PRESENT TO WHICH WALL SHEATHIN

(INCREASED SIZE), ATTACH TO EXISTING STUD W/ MIN. 3″ LONG FASTENERS @ 6″ O.C.

EXISTING TRUSS

GABLE END WALL

REQUIRED 2x RETROFIT STUD

(INCREASED SIZE), ATTACH TO EXISTING STUD W/ MIN. 3″ LONG FASTENERS @ 6″ O.C.

For SI: 1 inch = 25.4 mm, 1 pound = 4.4 N.

MIN. 2x4 LADDER RUNG BLOCKING @ 12″ O.C. VERTICAL

PLAN VIEW

HURRICANE TIE (MIN. 175 LB. CAPACITY) W/ 1¼″ LONG

METAL FRAMING ANGLE (MIN. 175 LB. CAPACITY PERPENDICULAR TO WALL) W/ 1¼″ LONG FASTENER (TYP) FROM RETROFIT STUD (INCREASED SIZE) TO LADDER BLOCKING

ELEVATION VIEW

METAL FRAMING ANGLE (MIN. 175 LB. CAPACITY PERPENDICULAR TO WALL) W/ 1¼″ LONG FASTENERS (TYP) FROM RETROFIT STUD (INCREASED SIZE) TO LADDER BLOCKING

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APPENDIX C—GUIDELINES FOR THE WIND RETROFIT OF EXISTING BUILDINGS

[BS] FIGURE C104.2.4(2)—LADDER BRACING FOR OMITTED RETROFIT STUD (CONVENTIONALLY FRAMED GABLE END)

EXISTING CONVENTIONALLY

FRAMED GABLE END WALL

REQUIRED 2x RETROFIT STUD (INCREASED SIZE), ATTACH TO EXISTING STUD W/ MIN. 3″ LONG FASTENERS @ 6″ O.C.

EXISTING CONVENTIONALLY

FRAMED GABLE END WALL

REQUIRED 2x RETROFIT STUD (INCREASED SIZE), ATTACH TO EXISTING STUD W/ MIN. 3″ LONG FASTENERS @ 6″ O.C.

MIN. 2x4 LADDER RUNG BLOCKING METAL FRAMING ANGLE (MIN. 175 LB. @ 12″ O.C. VERTICAL CAPACITY PERPENDICULAR TO WALL)W/ 1¼″ LONG FASTENER (TYP) FROM

RETROFIT STUD (INCREASED SIZE) TO PLAN VIEW LADDER BLOCKING

HURRICANE TIE (MIN. 175 LB. CAPACITY) W/ 1¼″ LONG FASTENERS (TYP) FROM EXISTING GABLE END STUD TO LADDER BLOCKING WHEN EXISTING VERTICAL MEMBER IS PRESENT

ELEVATION VIEW

METAL FRAMING ANGLE (MIN. 175 LB. CAPACITY PERPENDICULAR TO WALL) W/ 1¼″ LONG FASTENERS (TYP) FROM RETROFIT STUD INCREASED SIZE) TO LADDER BLOCKING

For SI: 1 inch = 25.4 mm, 1 pound = 4.4 N.

[BS] C104.2.5 Short horizontal brace. Where conditions exist that prevent installation in accordance with Section C104.2.2, C104.2.3 or C104.2.4, the horizontal braces shall be permitted to be shortened provided that installation is as indicated in Figure C104.2.5 and all of the following conditions are met.

1. The horizontal brace shall be installed across not fewer than two framing spaces, extend not less than 4 feet (1220 mm) from the gable end wall plus 2 [1] / 2 inches (64 mm) beyond the farthest roof or ceiling framing member from the gable end, and be fastened to each existing framing member with three 3-inch-long (76 mm) fasteners (#8 wood screws or 10d nails).
2. An anchor block shall be fastened to the side of the horizontal brace in the second framing space from the gable end wall as shown in Figure C104.2.5. The anchor block lumber shall have a minimum edge thickness of 1 [1] / 2 inches (38 mm) and the depth shall be at a minimum the depth of the existing roof or ceiling framing member. Six 3-inch-long (76 mm) fasteners (#8 wood screws or 10d nails) shall be used to fasten the anchor block to the side of the horizontal brace.
3. The anchor block shall extend into the space between the roof or ceiling framing members not less than one-half the depth of the existing-framing members at the location where the anchor block is installed. The anchor block shall be installed tightly between the existing framing members such that the gap at either end shall not exceed [1] / 8 inch (3.2 mm).
4. The use of omitted horizontal braces using the method of Section C104.2.3 adjacent to a short horizontal brace as defined in this section is not permitted.

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APPENDIX C—GUIDELINES FOR THE WIND RETROFIT OF EXISTING BUILDINGS

[BS] FIGURE C104.2.5—ANCHOR BLOCK INSTALLATION

FLAT HORIZONTAL BRACE

EXISTING FRAMING MEMBER

FLAT HORIZONTAL BRACE W/ MIN. (3) 3″ LONG FASTENERS @ CONNECTION TO EACH FRAMING

MEMBER

PLAN VIEW

ANCHOR BLOCK (MIN. SIZE EQUIVALENT TO EXISTING FRAMING MEMBER), ATTACH TO HORIZONTAL BRACE W/ MIN. 3″ LONG

FASTENERS AT MIN. 2½″ SPACING BETWEEN FASTENERS AND TO END OF

MIN. (3) 3″ LONG FASTENERS @ HORIZONTAL BRACE CONNECTION TO EACH FRAMING MEMBER

ANCHOR BLOCK (MIN. SIZE EQUIVALENT TO EXISTING FRAMING MEMBER), ATTACH TO HORIZONTAL BRACE W/ MIN. (6) 3″ LONG

EXISTING FRAMING MEMBER

SECTION VIEW

For SI: 1 inch = 25.4 mm.

[BS] C104.2.6 Installation of horizontal braces onto webs of trusses. Where existing conditions preclude installation of horizontal braces on truss top or bottom chords they shall be permitted to be installed on truss webs provided that all of the following conditions are met:

1. Horizontal braces shall be installed as close to the top or bottom chords as practical without altering the truss or any of its components and not more than three times the depth of the truss member to which it would ordinarily be attached.

2. A racking block, comprised of an anchor block meeting the definition of “Anchor block” in Section C102 or comprised of minimum [15] / 32 -inch (12 mm) plywood or [7] / 16 -inch (11.1 mm) oriented strand board (OSB), shall be fastened to the horizontal brace in the second framing space from the gable end wall. The racking block shall extend toward the roof or ceiling diaphragm so that the edge of the racking block closest to the diaphragm is within one-half the depth of the existing framing member from the diaphragm surface. The racking block shall be attached to horizontal braces using six fasteners (No. 8 wood screws or 10d nails) of sufficient length to provide 1 [1] / 2 inches (38 mm) of penetration into the horizontal brace.

3. Racking blocks shall be permitted to be fastened to any face or edge of horizontal braces between each web or truss vertical posts to which a horizontal brace is attached. Racking blocks shall be permitted to be on alternate sides of horizontal braces. Racking blocks shall be installed tightly between the lumber of truss members or truss plates such that the gap at either end shall be not greater than [1] / 8 inch (3.2 mm).

[BS] C104.2.7 Alternative method of installation of horizontal braces at truss ridges. Where conditions exist that limit or restrict installation of horizontal braces near the peak of the roof, ridge ties shall be added to provide support for the required horizontal brace. The top of additional ridge tie members shall be installed not greater than 16 inches (406 mm) below the existing ridge line or 4 inches (102 mm) below impediments. A minimum 2-inch by 4-inch (38 mm by 89 mm) nominal member shall be used for each ridge tie, and fastening shall consist of two 3-inch-long (76 mm) wood screws, four 3-inch-long (76 mm) 10d nails or two 3 [1] / 2 -inch-long (89 mm) 16d nails driven through and clinched at each top chord or web member intersected by the ridge tie as illustrated in Figure C104.2.7.

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APPENDIX C—GUIDELINES FOR THE WIND RETROFIT OF EXISTING BUILDINGS

[BS] FIGURE C104.2.7—DETAIL OF RETROFIT TIE INSTALLATION

WHEN ADDITIONAL SUPPORTS ARE NEEDED FOR HORIZONTAL BRACE NEAR RIDGE, MIN. 2x4 RAFTER TIE, ATTACH TO EACH INTERSECTING MEMBER

REQUIRED 2x RETROFIT STUD, ATTACH TO EXISTING STUD IN ACCORDANCE WITH SECTION C104.2.7

FLAT 2x4 HORIZONTAL BRACES

INSTALL 2x4 COMPRESSION BLOCK (TIGHT FIT) BETWEEN CENTER EXISTING GABLE END STUD OR RETROFIT STUD (TOP AND BOTTOM)

2x4 COMPRESSION BLOCK OF REQUIRED LENGTH, ATTACH TO HORIZONTAL BRACE W/ REQUIRED NUMBER OF 3″ LONG FASTENERS

CENTER FLAT 2x4 HORIZONTAL BRACES @ SIDE OF CENTER EXISTING GABLE END

STUD AND LINE WITH RETROFIT STUD

ELEVATION VIEW

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

[BS] C104.2.8 Interrupted horizontal braces. Where conditions exist that prevent the installation of a continuous horizontal brace then horizontal braces shall be permitted to be interrupted using the methods shown in Figures C104.2.8(1), C104.2.8(2), and C104.2.8(3). For interruptions that occur in the attic framing space closest to the gable end, nine 3-inch (76 mm) fasteners shall be used to connect each section of the interrupted horizontal braces. For interruptions that occur in the second attic space from the gable end, six 3-inch (76 mm) fasteners shall be used to connect each section of the interrupted horizontal braces. For interruptions that occur in the attic framing space farthest from the gable end, three 3-inch (76 mm) fasteners shall be used to connect each section of the interrupted horizontal braces. Horizontal braces shall be continued far enough to allow connections to three existing roof framing members as shown in Figure C104.2.8(1), C104.2.8(2) or C104.2.8(3). Fasteners shall be spaced in accordance with Section C103.5.3. Horizontal braces shall be the same width and depth as required for an uninterrupted member.

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APPENDIX C—GUIDELINES FOR THE WIND RETROFIT OF EXISTING BUILDINGS

[BS] FIGURE C104.2.8(1)—SPLICED HORIZONTAL BRACES

For SI: 1 inch = 25.4 mm.

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APPENDIX C—GUIDELINES FOR THE WIND RETROFIT OF EXISTING BUILDINGS

[BS] FIGURE C104.2.8(2)—SPLICED HORIZONTAL BRACES

For SI: 1 inch = 25.4 mm.

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APPENDIX C—GUIDELINES FOR THE WIND RETROFIT OF EXISTING BUILDINGS

[BS] FIGURE C104.2.8(3)—SPLICED HORIZONTAL BRACES

For SI: 1 inch = 25.4 mm.

[BS] C104.2.9 Piggyback gable end frames. Piggyback gable end frames (gable end frames built in two sections one above the other) shall be permitted to be retrofitted if either of the following cases is true:

1. The existing studs in both the upper gable end frames and the lower gable end frames to which wall sheathing, panel siding, or other wall covering are attached are sufficiently in line that retrofit studs can be installed and connections made between the two with retrofit stud(s).
2. Existing studs in the upper frame are not sufficiently in line with the studs in the frame below and the existing studs in the upper frame are 3 feet (91 cm) or shorter.

For Condition 1, both the lower stud and the upper stud shall be retrofitted using the methods of Section C104.2. For Condition 2, the retrofit stud shall be connected to the lower studs using the methods of Section C104.2 and be continuous from the bottom horizontal brace to the top horizontal brace. Connection is not required between the retrofit stud and the upper stud. In both conditions the bottom chord of the piggyback truss section shall be fastened to each retrofit stud using a connector with minimum axial capacity of 175 pounds (778 N).

all be connected to the lower studs using the methods of Section C104.2 and be continuous from the bottom horizontal brace to the top horizontal brace. Connection is not required between the retrofit stud and the upper stud. In both conditions the bottom chord of the piggyback truss section shall be fastened to each retrofit stud using a connector with minimum axial capacity of 175 pounds (778 N).

[BS] C104.3 Retrofit studs. Retrofit studs shall be installed in accordance with Section C104.3.1 using one of the five methods of Section C104.3.2, C104.3.3, C104.3.4, C104.3.5 or C104.3.6. Figure C104.3 shows these methods of installation. For the Retrofit Configuration obtained from Table C104.2, the size of retrofit studs shall be as indicated in Table C104.4.1 or Table C104.4.2. Retrofit studs shall extend from the top of the lower horizontal brace to the bottom of the upper horizontal brace except that a maximum gap of [1] / 8 inch (3.2 mm) is permitted at the bottom and [1] / 2 inch (12.7 mm) at the top. Where wall sheathing, panel siding or other wall covering is fastened to a conventionally framed gable end, retrofit studs shall be applied in accordance with Section C104.2.1.

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APPENDIX C—GUIDELINES FOR THE WIND RETROFIT OF EXISTING BUILDINGS

[BS] FIGURE C104.3—METHOD OF INSTALLING RETROFIT STUDS

For SI: 1 inch = 25.4 mm.

[BS] C104.3.1 Fastening. Where nail plates are not used, retrofit studs shall be attached to existing studs using 3-inch (76 mm) fasteners at not greater than 6 inches (152 mm) on center but not closer than 2 [1] / 2 inches (64 mm) on center with fasteners not closer to ends of members than 2 [1] / 2 inches (64 mm).

[BS] C104.3.2 Method #1: Face-to-edge or face-to-face method. Retrofit studs shall be installed immediately adjacent to existing gable end wall studs as indicated in Figure C104.3(a). The retrofit studs shall overlap the edge or side of the existing stud by not less than 1 [1] / 4 inches (32 mm). Fasteners shall be installed as specified in Section C104.3.1.

[BS] C104.3.3 Method #2: Face-to-face offset method. Retrofit studs shall be installed against the face of existing studs as indicated in Figure C104.3(b) such that the faces overlap not less than 1 [1] / 2 inches (38 mm) and the edge distance to fasteners is not less than [3] / 4 inch (19.1 mm). Fasteners shall be installed as specified in Section C104.3.1.

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APPENDIX C—GUIDELINES FOR THE WIND RETROFIT OF EXISTING BUILDINGS

[BS] C104.3.4 Method #3: Butted retrofit stud method. Provided that all of the following fastening conditions are met, retrofit studs shall be permitted to be butted by their edge to existing studs with the addition of nail plates as indicated in Figure C104.3(c) and Figure C104.3.4.

1. The narrow edge of retrofit studs shall be installed against the narrow or the wide face of existing studs.

2. Not fewer than two nail plates shall be used.

3. Fasteners used to secure nail plates to studs shall be a minimum 1 [1] / 4 inches (32 mm) long (#8 wood screws or 8d nails).

4. Fasteners placed in nail plates shall have a minimum end distance of 2 [1] / 2 inches (64 mm) for both studs and a maximum end distance of 6 inches (152 mm) from the ends of the shorter stud.

5. Fasteners shall have a minimum [1] / 2 -inch (12.7 mm) edge distance. Fasteners shall be placed not greater than 1 [1] / 2 inches (38 mm) from the abutting vertical edges of existing studs and retrofit studs.

6. There shall be at least three fasteners through nail plates into all existing and retrofit studs to which the nail plate is attached.

7. Nail plates with three fasteners onto a single existing or retrofit stud shall be spaced not greater than 15 inches (38 cm) on center.

8. Nail plates with more than three fasteners onto a single existing or retrofit stud shall be spaced not greater than 20 inches (51 cm) on center.

9. Fasteners used to secure nail plates shall be spaced vertically not less than 1 [1] / 2 inches (38 mm) on center. Staggered fasteners used to secure nail plates shall be spaced horizontally not less than [1] / 2 inch (12.7 mm).

[BS] FIGURE C104.3.4—NAIL PLATE FASTENING

ELEVATION VIEW

A MINIMUM OF 2½″ AND A MAXIMUM OF 6″ FROM

THE END OF THE SHORTER OF

THE EXISTING OR RETROFIT

STUDS.

4. FASTENERS ON EXISTING STUD SHALL BE A MINIMUM OF ½″ FROM EITHER EDGE.

5. A SET OF FASTENERS SHALL BE A MINIMUM OF ½″ FROM THE EDGE NEAREST THE

EXISTING STUD AND A MAXIMUM OF 1¼″ FROM THE EDGE OF THE

RETROFIT STUD NEAREST

THE EXISTING STUD.

SEE NOTE BELOW.

6. IN-LINE FASTENERS SHALL BE

SPACED VERTICALLY A MINIMUM OF 1½″ ON CENTER. IN LINE FASTENERS SHALL BE SPACED HORIZONTALLY A MINIMUM OF ½″ AND A MINIMUM OF 2½″

7. THE DISTANCE BETWEEN

FASTENERS ON PLATES SHALL

BE A MAXIMUM OF 20″

ON CENTER.

8. FASTENERS SHALL BE MINIMUM 1¼″ LONG (#8 WOOD SCREWS OR 8D NAILS)

STUD SIZES MAY DIFFER FROM THOSE SHOWN.

DIAGONAL HATCHES INDICATE ALLOWABLE LATERAL RANGE

FOR FASTENERS.

THE RELATIONSHIP BETWEEN STUDS AND PLATES WILL VARY

ACCORDING TO THE PARTICULARS OF THE METHOD USED.

For SI: 1 inch = 25.4 mm.

[BS] C104.3.5 Method #4: Offset retrofit stud method. Retrofit studs may be offset from existing studs by use of nail plates as shown in Figure C104.3(d) such that the vertical corner of a retrofit stud shall align with the vertical corner of an existing stud as indicated in Figure C104.3(d) and Figure C104.3.4, and the fastening conditions of Section C104.3.4 are met.

[BS] C104.3.6 Method #5: Nailer with retrofit stud method. Retrofit studs and existing studs shall be permitted to be connected using noncontinuous 2-inch by 4-inch (38 mm by 89 mm) nailers as indicated in Figure C104.3(e) provided that the following conditions are met.

1. Both the existing stud and the retrofit stud shall be butted to nailers and both shall be fastened to the nailer with 3-inchlong (76 mm) fasteners (#8 wood screws or 8d nails). Fasteners connecting each stud to the nailer shall be a spaced 6 inches (152 mm) o.c.

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APPENDIX C—GUIDELINES FOR THE WIND RETROFIT OF EXISTING BUILDINGS

2. Fasteners into nailers from any direction shall be offset vertically by not less than 2 [1] / 2 inches (64 mm).
3. Fasteners into nailers shall be not less than 2 [1] / 2 inches (64 mm) but not more than 6 inches (152 mm) from the end of the shorter of the existing stud and retrofit stud to which they are fastened.

[BS] C104.3.7 Reduced depth of retrofit studs. Retrofit studs may be reduced in depth by notching, tapering or other methods at any number of locations along their length provided that all of the following conditions are met:

1. Retrofit studs to be reduced in depth shall be sized such that the remaining minimum depth of member at the location of the notch (including cross-cut kerfs) shall be not less than that required by Table C104.4.1 or Table C104.4.2.

2. Reduced in-depth retrofit stud shall not be spliced within 12 inches (30 cm) of the location of notches. Splice members shall not be notched.

3. The vertical extent of notches shall not exceed 12 inches (30 cm) as measured at the depth of location of reduced depth.

4. A reduced in-depth retrofit stud member shall be fastened to the side of the existing gable end wall studs in accordance with Section C104.3.1. Two additional 3-inch (76 mm) fasteners (#8 wood screws or 10d nails) shall be installed on each side of notches in addition to those required by Section C104.3.1.

[BS] C104.3.8 Retrofit stud splices. Retrofit studs greater than 8 feet (244 cm) in height may be field spliced in accordance with Figure C104.3.8.

[BS] FIGURE C104.3.8—RETROFIT STUD SPLICES

ELEVATION VIEW SECTION VIEW

REQUIRED CONNECTION TO

HORIZONTAL BRACE

EXISTING GABLE END STUD

REQUIRED 2x RETROFIT STUD W/ 3″ LONG FASTENERS @ 6″ O.C.

50″ LONG SPLICE MEMBER (MATCH SIZE OF RETROFIT STUD)

                         - CENTER ON SPLICE LOCATION

INSTALL MINIMUM (27) 3″ LONG FASTENERS FROM SPLICE MEMBER TO RETROFIT STUD (EACH SIDE OF SPLICE LOCATION)

REQUIRED CONNECTION TO

HORIZONTAL BRACE

NOTE:

TUD
IT
.
¾″ MIN.
O.C.
2½″
ER
STUD)
ATION
ONG
EMBER
IDE OF

SPLICE LOCATION MAY BE REQUIRED AT TOP OF GABLE END STUD IF HEIGHT > 11′-0″ TO 12′-0″

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

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APPENDIX C—GUIDELINES FOR THE WIND RETROFIT OF EXISTING BUILDINGS

[BS] C104.4 Connection between horizontal braces and retrofit studs. Connections between horizontal braces and retrofit studs shall comply with Section C104.4.1 or C104.4.2. Each retrofit stud shall be connected to the top and bottom horizontal brace members with a minimum 20-gage 1 [1] / 4 -inch-wide (32 mm) flat or coil metal strap with prepunched holes for fasteners. Straps shall be fastened with 1 [1] / 4 -inch-long (32 mm) fasteners (#8 wood screws or 8d nails) with the number of fasteners as indicated in Table C104.4.1 and Table C104.4.2. Fasteners shall be not closer to the end of lumber than 2 [1] / 2 inches (64 mm).

[BS] C104.4.1 L-bent strap method. Retrofit studs shall be connected to horizontal braces or to strong backs in accordance with Figure C104.2(1), C104.2(2) or C104.2.3, and shall comply with the following conditions:

1. A strap shall be applied to the edges of a retrofit stud nearest the gable end wall and to the face of horizontal braces using at each end of the strap the number of fasteners specified in Table C104.4.1. Straps shall be long enough so that each strap extends sufficient distance onto the vertical face of the retrofit stud that the fastener closest to the ends of the studs is not less than 2 [1] / 2 inches (64 mm) from the end of the stud. Straps shall be permitted to be twisted to accommodate the transition between the tops of retrofit studs and horizontal bracings following roof pitches.
2. Compression blocks shall be installed on the horizontal braces directly against either the existing vertical gable end wall stud or the retrofit stud. Figure C104.2(1) (trusses) and Figure C104.2(2) (conventionally framed) show the installation of the compression block against the existing vertical gable end wall stud with the strap from the retrofit stud running beside the compression block. Compression blocks shall be permitted to be placed over straps. Compression blocks shall be fastened to the horizontal braces with not fewer than the minimum number of 3-inch-long (76 mm) fasteners (#8 wood screws or 10d nails) specified in Table C104.4.1. End and edge distances for fasteners shall be in accordance with Section C103.5.3.

from the retrofit stud running beside the compression block. Compression blocks shall be permitted to be placed over straps. Compression blocks shall be fastened to the horizontal braces with not fewer than the minimum number of 3-inch-long (76 mm) fasteners (#8 wood screws or 10d nails) specified in Table C104.4.1. End and edge distances for fasteners shall be in accordance with Section C103.5.3.

[BS]TABLE C104.4.1—ELEMENT SIZING AND SPACING FOR L-BENT RETROFIT METHOD

[BS] C104.4.2 U-bent strap method. Retrofit studs shall be connected to horizontal braces in accordance with Figure C104.2(3) or C104.2(4), shall be limited to Retrofit Configurations A and B as defined in Table C104.2, and shall comply with the following conditions:

1. Straps of sufficient length to meet the requirements for the number of fasteners in accordance with Table C104.4.2 and meet the end distance requirements of Section C103.5.3 shall be shaped around retrofit studs and fastened to the edges of horizontal braces. Straps shall wrap the back edge of the retrofit stud snugly with a maximum gap of [1] / 4 inch (6.4 mm). Rounded bends of straps shall be permitted. One fastener shall be installed that connects each strap to the side of the associated retrofit stud.

2. The horizontal brace shall butt snugly against the retrofit stud with a maximum gap of [1] / 4 inch (6.4 mm).

3. Straps shall be permitted to be twisted to accommodate the transition between the tops of retrofit studs and horizontal braces that follow the roof pitch.

[BS] TABLE C104.4.2—ELEMENT SIZING AND SPACING FOR U-BENT RETROFIT METHOD

[BS] C104.5 Connection of gable end wall to wall below. The bottom chords or bottom members of wood-framed gable end walls shall be attached to the wall below using one of the methods prescribed in Section C104.5.1 or C104.5.2. The particular method chosen shall correspond to the framing system and type of wall construction encountered.

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APPENDIX C—GUIDELINES FOR THE WIND RETROFIT OF EXISTING BUILDINGS

[BS] C104.5.1 Gable end frame. The bottom chords of the gable end frame shall be attached to the wall below using gusset angles. Not fewer than two fasteners shall be installed into the bottom chord. The gusset angles shall be installed throughout the portion of the gable end where the gable end wall height is greater than 3 feet (91 cm) at the spacing specified in Table C104.5.1. Connection to the wall below shall be by one of the following methods:

1. For a wood-frame wall below, not fewer than two fasteners shall be installed. The fasteners shall be of the same diameter and style specified by the gusset angle manufacturer and sufficient length to extend through the double top plate of the wall below.

2. For a concrete or masonry wall below without a sill plate, the type and number of fasteners into the wall shall be consistent with the gusset angle manufacturer’s specifications for fasteners installed in concrete or masonry.

3. For a concrete or masonry wall below with a 2x sill plate, the fasteners into the wall below shall be of the diameter and style specified by the gusset angle manufacturer for concrete or masonry connections; but, long enough to pass through the wood sill plate and provide the required embedment into the concrete or masonry below. Alternatively, the gusset angle can be anchored to the sill plate using four each 1 [1] / 2 -inch-long (38 mm) fasteners of the same type as specified by the gusset angle manufacturer for wood connections, provided that the sill plate is anchored to the wall on each side of the gusset angle by a [1] / 4 -inch-diameter (6.4 mm) masonry screw with 2 [3] / 4 inches (70 mm) of embedment into the concrete or masonry wall. A [1] / 4 -inch (6.4 mm) washer shall be placed under the heads of the masonry screws.

mm) fasteners of the same type as specified by the gusset angle manufacturer for wood connections, provided that the sill plate is anchored to the wall on each side of the gusset angle by a [1] / 4 -inch-diameter (6.4 mm) masonry screw with 2 [3] / 4 inches (70 mm) of embedment into the concrete or masonry wall. A [1] / 4 -inch (6.4 mm) washer shall be placed under the heads of the masonry screws.

[BS]TABLE C104.5.1—SPACING OF GUSSET ANGLES

[BS] C104.5.2 Conventionally framed gable end wall. Each stud in a conventionally framed gable end wall, throughout the length of the gable end wall where the wall height is greater than 3 feet (914 mm), shall be attached to the bottom or sill plate using a stud to plate connector with minimum uplift capacity of 175 pounds (778 N). The bottom or sill plate shall then be connected to the wall below using one of the following methods:

1. For a wood frame wall below, the sill or bottom plate shall be connected to the top plate of the wall below using [1] / 4 -inchdiameter (6.4 mm) lag bolt fasteners of sufficient length to penetrate the bottom plate of the upper gable end wall and extend through the bottom top plate of the wall below. A washer sized for the diameter of the lag bolt shall be placed under the head of each lag bolt. The fasteners shall be installed at the spacing indicated in Table C104.5.2.
2. For a concrete or masonry wall below, the sill or bottom plate shall be connected to the concrete or masonry wall below using [1] / 4 -inch-diameter (6.4 mm) concrete or masonry screws of sufficient length to provide 2 [3] / 4 inches (70 mm) of embedment into the top of the concrete or masonry wall. A washer sized for the diameter of the lag bolt shall be placed under the head of each lag bolt. The fasteners shall be installed at the spacing indicated in Table C104.5.2.

[BS]TABLE C104.5.2—SPACING OF LAG OR MASONRY SCREWS USED TO
CONNECT SILL PLATE OF GABLE END WALL TO TOP OF THE WALL BELOW

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APPENDIX C—GUIDELINES FOR THE WIND RETROFIT OF EXISTING BUILDINGS

[BS]TABLE C104.5.2—SPACING OF LAG OR MASONRY SCREWS USED TO
CONNECT SILL PLATE OF GABLE END WALL TO TOP OF THE WALL BELOW—continued

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CALIFORNIA EXISTING BUILDING CODE – MATRIX ADOPTION TABLE

APPENDIX C

CHAPTER C2 – ROOF DECK FASTENING FOR HIGH-WIND AREAS

Not adopted by the State of California (May be available for adoption by local ordinance. See Section 1.1.11.)

The state agency does not adopt sections identified with the following symbol: † The Office of the State Fire Marshal’s adoption of this chapter or individual sections is applicable to structures regulated by other state agencies pursuant to Section 1.11.

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APPENDIX C—GUIDELINES FOR THE WIND RETROFIT OF EXISTING BUILDINGS

CHAPTER C2 ROOF DECK FASTENING FOR HIGH-WIND AREAS