This document provides instructions for seismic retrofitting of homes, including bolting cripple walls to the foundation, securing cripple walls to floor joists, and installing plywood shear panels. It discusses proper techniques for bolting and securing walls, sizes of bolts, replacing bolts with foundation plates where space is limited, and different methods for attaching plywood panels to strengthen walls. The document also mentions replacing rotted wood, updating plumbing and wiring, and using shear walls and anchor plates to seismically reinforce the connection between the house and foundation.

1. Seismic` Retrofitting

2. 1. Bolt cripple walls
to foundation
2. Secure cripple
walls to the floor
joists
3. Install plywood
shear panels

3. • Bolting is only of value where
walls have been braced with
plywood
• The number of bolts is
calculated to have the same
resistance capacity as the
plywood

5. Bearing plates increase
strength of bolt-to-wood
SEAOSC Research
connection

6. • Oversized bolt holes are
found in most existing bolt
installations.
• More than 1/16 of an inch
larger than diameter of bolt is
considered oversized.

7. • Caused by over-sized
holes
• Over-sized holes are
common because they
allow builders to adjust the
position of the mudsill

8. Foundation plates replace bolts where drill-space is unavailable

9. Movement prevented by
shear transfer ties

11. There are three ways to attach
a plywood panel to the
mudsill:
• Directly to Flush Framing
• The Nailed Blocking
Method
• The Flush Cut Method

13. 2x4 blocks installed between 2x4 studs
on 2x6 mudsill

16. • Improper nailing often
causes wood splitting
• Pneumatically driven
staples can be driven
closer and reduce
splitting at time of
driving and when
loaded in shear

17. Updated plumbing, wiring and structural modifications

18. Old-fashioned, inconsistent and odd framing

19. Replacing rotted or pest-damaged wood

21. Shear walls with finished-to-match panels between

22. Anchor plates and shear transfer ties house to foundation

23. Eddie Sandoval
Tel:415-680-2112
esandoval@cal-insure.com