Kent

Helical piles in Kent, Washington

Kent sits in the Green River Valley south of Seattle. The DNR 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.

Frost is mild west of the Cascades. Seattle's code requires exterior footings at least 12 inches below undisturbed ground, and many Washington jurisdictions regulate geologically hazardous areas, so projects near steep slopes or mapped landslides may need a geotechnical report. The engineer of record typically sets pile depth and installation torque.

Helical pile companies serving Kent

Two companies are based in Kent.

• McDowell NW Pile King, Inc.: installs helical piles and anchors alongside pipe piles and shoring in the Seattle and Portland areas.
• McDowell Northwest, Inc: a piling contractor serving Northwest builders since 1946, with helical pipe piling offered through McDowell Pile King.

Costs and what to ask

HomeGuide puts typical installed cost at roughly $2,000 to $4,000 per helical pier nationally. Washington projects can move toward the upper end where slopes, engineering, or waterfront access add work. Read our helical pier cost guide for what a quote should include.

Questions to put to any installer:

• Is the pile layout stamped by an engineer for liquefiable valley soils?
• Will the crew log torque at every pile and hand over the log at the end?
• What are the shaft size and helix configuration, and how is the steel protected for wet soil?
• Is a permit required through the City of Kent, and who handles it? What does the warranty include in writing?

For the wider picture, see our page on Washington helical pile installers.