SeaTac

Helical piles in SeaTac, Washington

Western Washington's wet winters, glacial soils and steep bluffs make landslides a regular concern, and the Washington Geological Survey is building a lidar-based landslide inventory for the Puget Sound region. DNR's earthquake and fault resources note that river valleys, deltas, tidal flats and artificial fill can liquefy during strong shaking.

Helical piles give engineers a way to reach competent glacial till or dense sand beneath soft or loose surface soils without large excavations. Seattle's residential code requires footings at least 12 inches below undisturbed ground, which reflects the mild marine climate. Projects near steep slopes or mapped landslides may need a geotechnical report, and the engineer of record typically sets the pile depth and the installation torque tied to design capacity. SeaTac sits in the Puget Sound region, so ask the city which hazard areas apply to your parcel before design begins.

Helical pile companies serving SeaTac

One company based in SeaTac is listed.

• Matvey Foundation Repair: Listed for foundation repair, waterproofing and concrete work. Ask which foundation systems it installs before booking.

Costs and what to ask

HomeGuide reports that helical piers cost about $2,000 to $4,000 each installed nationally, with about $3,000 typical. Washington projects can move toward the upper end where slopes, engineering or waterfront access add work. See our helical pier cost guide for the main cost drivers. Questions to ask:

• Does my lot fall in a mapped landslide or liquefaction area that needs a geotechnical report?
• Will the engineer of record set depth and verification torque?
• Will you provide torque logs?
• Who pulls the permit, and what does the warranty cover?

Nearby listings include Kent and Renton. See all Washington helical pile installers.