Seismic Retrofit Evaluation in Gresham, OR
Gresham's post-war stock is, in retrofit terms, close to the best case. These are single-storey or storey-and-a-half houses on simple rectangular footprints with continuous perimeter foundations and low cripple walls, and the concrete is generally later and more consistent than the early-century pours in inner Portland.
That matters practically rather than academically. Anchorage into sound mid-century concrete is straightforward, the cripple walls are short enough to brace with plywood rather than anything engineered, and the simple footprint means the load path is easy to follow and easy to make continuous. It is the version of this work that most reliably comes in at the low end.
The complication to look for is additions. A lot of this stock has been extended, and an addition built decades later frequently has a different foundation type and no connection to the original lateral system. The retrofit then has to treat two structures rather than one, and that is usually what moves a Gresham job away from the standard scope.
What We Look At Here
- Anchor bolt presence and spacing, and concrete quality for new anchorage
- Cripple wall height and existing bracing, if any
- Whether additions have their own foundation type and lateral system
- Continuity of the load path across the junction between original house and additions
- Post and girder condition in the crawl space, and connections at each end
- Garage openings, which interrupt the perimeter and often need a specific detail
More on the service itself: Seismic Retrofit Evaluation. More on the area: Gresham.
Questions
Frequently Asked Questions
Is a retrofit cheaper on a Gresham post-war house?
Usually, yes. Simple footprints, low cripple walls and sounder mid-century concrete make for a straightforward scope. Additions are the main thing that changes it, since they often need treating as a second structure.