Honestly, crawling under the house is half the job—expect dirt in your ears and a few bruises. For cripple wall bracing, the general rule is plywood sheathing on all sides if you’ve got any height over 12-18 inches. Metal straps alone don’t really cut it for anything but the shortest walls. As for retrofitting, it’s not rocket science, but you’ll be drilling into concrete and working in tight spots. The hardest part is usually maneuvering the panels into place and dealing with whatever surprises your old house throws at you... like finding a weird pipe right where you want to bolt something down. It’s doable if you’re patient, but yeah, there will be swearing.
I gotta say, I went the “metal straps and blocking” route on my 1920s place (mostly because I chickened out at the thought of hauling full plywood sheets into that crawlspace). Not saying it’s the gold standard, but my inspector seemed fine with it for the shorter walls—like, under a foot. Anything taller, yeah, I get why people swear by plywood.
Couple things I learned the hard way:
- If you’re drilling into old concrete, expect to hit at least one spot where your bit just… refuses. Like it’s found fossilized rebar or something.
- The “weird pipe” thing is real. Mine was an ancient gas line that nobody could explain.
- Don’t underestimate how much time you’ll spend just figuring out how to wedge yourself between ductwork and spider webs.
Honestly, if you’re not up for full sheathing, there are some pre-fab panels out there that can save your back (and sanity). They cost more but might be worth it if you value your knees. Just my two cents—sometimes good enough really is good enough, depending on what you’re working with.
Metal straps and blocking definitely have their place, especially in those tight crawlspaces where plywood just isn’t happening. I’ve done both, and honestly, sometimes you just gotta work with what you’ve got. One thing I’d add—if you’re worried about the eco side, there are recycled-content panels that are lighter and easier to maneuver than full plywood sheets. Not cheap, but less waste and easier on your body. Also, don’t forget to check if your bolts have proper washers—seen too many jobs where they skipped that and it made a difference in an actual quake.
Also, don’t forget to check if your bolts have proper washers—seen too many jobs where they skipped that and it made a difference in an actual quake.
That’s a good callout. I’ve crawled under plenty of houses where the bolts looked solid at first glance, but then you realize there’s no plate washer or it’s just a tiny one. Makes you wonder how many folks think they’re set when they’re really not. Ever run into those old-school split washers? I still see them sometimes and they’re basically useless for seismic work. Curious if anyone’s tried those newer Simpson hold-downs in tight spaces—seems like overkill, but maybe worth it?
Those split washers are like the duct tape of the 70s—everyone used them, but nobody really knew if they did anything. I can’t count how many times I’ve yanked out a rusty split washer and replaced it with a beefy plate washer, and you just feel better about your work after. It’s wild how something as simple as the right washer size can make or break your retrofit.
As for the Simpson hold-downs, I’ve squeezed a few in places where you’d swear only a squirrel could fit. Overkill? Maybe. But if you’re already down there eating dust and dodging spider webs, might as well do it right. The peace of mind is worth more than saving a few bucks on hardware, at least for me. That said, I still think folks go crazy with hardware sometimes—bolting every two inches like they’re prepping for The Big One tomorrow. There’s a balance. But yeah, tiny washers are basically just wishful thinking in quake country...