[quote=UCGal]Scarlett –
Our house (one of your target areas – UC) was built in 1963. It had copper pipes for both supply and waste.[/quote]
Copper lines for waste too?? Geesh.. not supposed to use copper on wastelines because it corrodes too easily. Supposed to be cast iron or ABS. I believe that is also written into building codes.

[quote=UCGal]We also have upgraded/earthquake-retrofitted sections. This is much less of an issue in a single story house per my husband. If he opens a wall to do anything (add a new outlet, run some new wire/cables) he goes ahead and opens an entire section – adds diagonal bracing, adds insulation (if it’s an exterior wall), if it’s ground floor he adds more bolts to the foundation and strapping to the upper floors. When he replaces the wall he’s opened up, he uses plywood to give it sheer wall stiffness.

This is all probably overkill – he’s doing more than current earthquake standards. But it makes him sleep better at night. To paraphrase the old saying “happy husband, happy life”.[/quote]
Actually much of it is required for new construction. The between floor strapping is generally only required in tornado zones though. He doesn’t need to add diagonal bracing if he is puts 4×8 sheets of plywood in when closing up.

It looks like your husband is paying attention to some research on the subject, because strapping is recommended for over-code construction in earthquake zones.