What matters for project planning
Slope is the item that shapes this work most, because on a mountainside lot a crawl space is rarely uniform: it can be shallow at the uphill wall and tall enough to stand in at the downhill one, which changes access, drainage and the vapor barrier detail within a single house. Uphill groundwater arriving at the high wall is the moisture route that flat-site guidance never describes. Retaining conditions matter here too, since a failing wall above the house changes where water goes before it ever reaches the crawl space. Historic review is worth confirming only where the work produces a visible change at grade, and flood status where the parcel is mapped.
Official sources
Verify the property, not just the city
Citywide context cannot establish a parcel’s flood zone, historic designation, stream buffer, permit requirements, soil conditions, or concealed construction. Confirm those items with the appropriate authority and selected provider before work begins.
Sources reviewed June 20, 2026. External requirements and maps can change.