We bolt wood-framed houses down to their concrete foundations and sheathe the short crawl-space walls with plywood, for homes in Beaverton, Cedar Mill, Bethany and the west side of Portland. Portland-area retrofits mostly come in at $2,800-$10,000 with materials, around $5,000 for a typical one (market data, November 2026) .
Slava, who does the work himself, brings seven years of hands-on experience.
What's involved in retrofitting a house for earthquakes?
A house sits on its foundation mostly by weight. In a hard shake, the frame can slide off the concrete, or the short stud walls under the floor (cripple walls) can fold over. A retrofit fixes both weak points from below:
- Anchor bolts drilled through the wood sill into the concrete, each with a square steel washer. Sound concrete takes expansion anchors; tired concrete gets adhesive ones.
- Plywood panels nailed over the cripple-wall studs on a close nail pattern, with holes drilled in every sheet so the cavity can breathe.
- Blocking and steel clips that tie the floor framing to the braced wall.
- Side-mounted plates where the floor rests straight on the foundation and there's no room to drill down from above.
That last case comes up a lot in Beaverton's ranches and split-levels with shallow crawl spaces (Beaverton service area) .
How much does seismic retrofitting cost around Portland?
| Work | Range | Middle | Priced |
|---|---|---|---|
| Sill bolts and plywood on the cripple walls | $2,800 to $10,000 | $5,000 | per house, materials in |
| Quake-prep visit: tank straps, tall furniture fixed to studs, cupboard catches | $400 to $1,500 | $800 | per house, labour alone |
Both lines are regional market figures, not yet our own invoices . The market sheet behind the first one assumes about 35 hours of labour, with materials near a quarter of the bill. Our seismic retrofit cost guide walks through each part of that figure.
A quote climbs when walls need lots of new blocking, when the house has no cripple walls at all, when the hatch is tight or ducts are in the way, when rot or insect damage must be repaired first, and most of all with a masonry foundation, which calls for an engineer. Any bolting job here tops $2,000, so Oregon wants it on paper; see the state's contract rules .
How can I tell if my house needs a retrofit?
Take a flashlight to the hatch and look where the wood sill meets the concrete. Bolt heads with washers every few feet are a good sign. No bolts, cripple walls covered by nothing but the siding outside, crumbling or cracked concrete, or punky wood at the sill all mean it's worth a closer look.
Portland's retrofit page notes that lots of houses from before 1960 were never bolted down. It adds that some 1970s houses had bolts and still slid, because their cripple walls were weak. Oregon's seller disclosure form also asks whether a pre-1974 house has been bolted, so the answer follows you to a sale.
Post-war tract streets fill much of Cedar Hills, and Cedar Mill leans toward houses framed in the 1960s and '70s. A Bethany home from the 1990s or 2000s probably has its bolts already, though the flashlight check works the same .
Is a permit required for earthquake bolting?
Your address decides which office applies, so ask your city or county first.
Inside Portland city limits, yes. The city offers a prescriptive route: you sketch a foundation plan, tick which of its standard details apply, go over it with a city plan reviewer and pay the fee. That route is for houses with one or two units and no more than three floors, cripple walls four feet tall at most (14 inches on a three-floor house), unbroken concrete under the whole perimeter, and a lot that isn't steeper than 3:1. Steeper than that, an engineer or architect draws the plan. Where the foundation steps down, each step gets a bolt near either end.
In unincorporated Washington County, the county's seismic page says it requires no permit and no inspection for this work. Ask, though, and it will issue a voluntary one. We think that can be worth doing: an inspected permit leaves a record you can point to when the disclosure form or an insurer asks.
In the City of Beaverton, we haven't found a published seismic rule.
The slope limit matters on sloping lots in West Slope.
Is earthquake retrofitting worth it?
Oregon's emergency management office says the Cascadia Subduction Zone last ruptured in January 1700, in a quake now put near magnitude 9.0. It puts the odds of a 7.1-or-larger quake on that fault within 50 years at roughly 37 %.
Portland's page makes the case that a strengthened house is safer to be in and simpler to sell or cover. Ask your own agent what it means for your policy.
On free retrofits: the Earthquake Brace + Bolt grant that many articles mention is a California programme. The Washington County page names no grant at all.
Can a handyman bolt and brace a house?
Portland says an owner who's handy with a saw and a nail gun can legally do the prescriptive work, though most hire it out.
Our part is the prescriptive set: bolts, plywood, blocking, clips, and the quake-prep visit. When the owner has an engineer's plan, we build to it . On pre-1978 houses the plywood goes on from inside, never by pulling painted siding .
We don't install automatic gas shutoff valves, treat pests, remove asbestos wrap, replace foundations or brace chimneys; what we don't do has the full list .
Under west-side floors it stays damp from fall to spring, which is when a rotting sill gives itself away. Rot in siding or trim goes to our siding and rot repairs .
What else is worth fastening down before a quake?
The quake-prep visit deals with what tips, falls or flies: two straps around the water heater, bookcases and dressers screwed into studs, and child-style catches on the upper kitchen doors. Market labour for it is $400 to $1,500, most often near $800 . An old tank may be due for replacement first.
We don't touch gas lines; your gas utility explains how to shut the supply off.