Geotech report (only if site triggers it)

When you actually need this

Three triggers, any one of which means yes:

1. The lot is in an Environmentally Critical Area (ECA) — steep slope, landslide-prone, peat, liquefaction. SDCI flags ECA on the GIS lookup from step 0.1, and the ECA code page lists the categories. Common in West Seattle, Magnolia, parts of Mount Baker.
2. You're building a new foundation under the lifted house. New foundations on Seattle older-house lots benefit from a geotech read on bearing capacity, especially in fill areas (much of Ballard, parts of Wallingford).
3. The structural engineer's foundation assessment flagged soil-related questions. Settlement that suggests subsidence, water issues at the footing, or unknowns the engineer doesn't want to design around.

What the report covers

• Soil profile from one or two test pits or borings.
• Bearing capacity recommendations.
• Drainage and grading guidance.
• Seismic site classification (matters for the structural design).

When to skip it

Flat lot, no ECA designation, structural engineer says the existing foundation is adequate or needs only modest perimeter retrofit — you can skip the geotech. Most Seattle bungalow additions on level lots fall in this bucket.