Slide 54 of 67
Use the Proper Size Panel
- It is important to use the proper size panel
- 1994 UBC Requirements:
- Although the Uniform Building Code does not prescribe minimum dimensions for individual panels on shear walls, a minimum width of 24 inches is recommended to prevent any one local defect affecting performance.
- This criterion is used for floor loads and is recommended for shear walls.
- 1997 UBC Recommendations:
- The 1997 UBC recommends a 2:1 aspect ratio in Seismic Zones 3 and 4
- Minimum: 4' x 8’ panel on any standard eight-foot high shear wall.
- When the length of the shear wall exceeds four feet, the end panels should be at least 24 inches.
Mark Location of Studs on Panels
- To avoid improper fastening, mark location of stud on panels because you won’t be able to see the back of the wall once the panel is placed
- Retrofit work usually done from one side of the wall. Panels are held in place with a few nails until volume nailing is done later.
- When you are nailing it in, if you hit the edge it can feel just like the center.
- The number of fasteners that do not properly connect to the framing members or blocking cannot easily be determined after the sheathing is in place.
- To reduce the chance of improper fastening, contractors should mark the center of all framing members, blocking and hold-down end studs during sheathing installation.
- After all panels are in place, a “chalk” line can be snapped on the panels, which makes proper volume fastening easy.
Maintain Fire Resistive and Sound-Rated Construction
- When retrofit work replaces existing wall finishes, any fire resistive construction must be maintained
- One-hour fire resistive and sound-rated construction is required at walls separating dwelling units in the same building.
- One-hour fire-resistive construction is also required throughout three story apartments and when two story apartments have more than 3,000 square feet on the second floor.
- Some apartments may also use two-hour walls to get more allowable floor area.
- When these conditions exist, all required components of the wall assembly must be replaced.
- The addition of plywood or OSB panels will not affect the fire rating when attached directly to the framing and covered with the appropriate fire-resistive materials.
- In other words, put it back the way it was originally. Don’t change anything and don’t cut any corners because you may alter the fire resistivity of the building