Typical cost in Seattle
A dropped corner has a reason behind it, and we look for that reason before proposing anything. Push piers, helical piers and underpinning each come with limits, which are explained here.
We work in Seattle, Bryn Mawr-Skyway and White Center. Seattle homes built before 1960 amount to about 38 percent. Age alone does not show footing movement, so a visit checks the house; a sloping floor on its own does not mean piers.
Push piers go by mini-piers in HUD’s guide: steel pipes 2 to 8 inches across that hydraulic rams drive down next to the footing, using the building’s own weight as the reaction, until rock or adequate bearing soil is reached. HUD lists two drawbacks. The foundation or slab can crack if the method is used incorrectly, and it is economical only where a bearing layer is fairly close to the surface.
A helical pier is a steel shaft with one or more helical plates, advanced by rotation until it reaches stable soil and then fixed to the footing with a bracket. In HUD’s account, measuring torque during installation reveals actual bearing capacity, and soils of limited bearing capacity are where the method will not work.
In HUD’s account, underpinning means excavating under a settled wall and widening the footing so the load spreads across more soil. An engineer should design it, HUD says; it also calls the procedure dangerous, a job for experts, and one that may fail in silty or expansive soil.
A porch or bay on an inadequate foundation can settle unevenly, and HUD ties the resulting tapered crack, wider at one end, to differential settlement. In the house itself, the signs are floors that slope, door and window gaps, doors that stick, and cracks that step at corners.
Settlement is gradual in HUD’s description, not a sudden event, so there is time to establish the cause; a wall that visibly leans or a moving slope breaks that rule. Bring numbers to the first visit: level readings on the floor and dated pencil ticks at both ends of a crack.
HUD’s rehab guide lists the primary causes of foundation failure:
Seattle’s permit pages put two ground conditions on the city’s critical-area list that bear directly on settlement. Peat-settlement-prone sites hold peat and organic soil that may settle when land is developed or the water table drops. Liquefaction-prone sites have loose, saturated soil that can lose the strength to carry a building in an earthquake. The city’s ECA map and a geotechnical report show whether a lot is one of them.
HUD notes that water can wash fines out from under footings and reduce soil cohesion, which causes settlement.
SDCI’s Tip 316 lets foundation repair or replacement use the quicker subject-to-field-inspection permit only when the foundation is not designed as a retaining wall, is no more than 4 feet tall from the bottom of the footing, keeps its footprint and height, sits outside an ECA and comes with photographs of the damage. The same Tip sends foundation repair with pin piles to plan review and lists foundations that use piles, pipe piles and pin piles included, among projects needing full plan review. Whether a particular push or helical system counts as piles is a question for SDCI.
Where the site has a steep slope, a known or potential slide, liquefaction, landfill or peat settlement, SDCI says a geotechnical report is required for foundation alterations, and needing one rules out the quick permit unless the requirement is waived. Foundation alterations in a steep slope area, or within 15 feet of the upper or lower edge of one, need an exemption, relief or small project waiver approved before applying, or a land use permit.
On the cause of settlement, HUD’s rehab guide points to a structural or geotechnical engineer who specializes in the work and should be consulted. That is federal advice, and Seattle does not issue it as a rule. Engineering is outside our services: when a job needs an evaluation or stamped design, you hire the engineer separately.
SDCI separately issues emergency repair permits for structural damage caused by an emergency. The permit covers only that damage, and the application needs a letter from a structural or geotechnical engineer stating that the project is an emergency.
Piering cost follows the house and the ground. The main drivers:
Signs: floors that slope, cracks that taper, gaps over doors. To see whether movement continues, set a level on the floor and mark a crack with dated pencil lines. A visit then looks for the cause.
No winner overall. Where firm soil is within reach, push piers work; where bearing capacity is limited, helical piers fall short. A geotechnical investigation shows what is below your footing, which decides the matter.
That cannot be promised. Misused push piers can crack the foundation, HUD warns, and whether the house can be lifted at all turns on framing, soil and the engineer’s design.
When the floor slopes above a crawlspace, posts may be at fault instead of the footing, so crawlspace post and beam repair is a useful companion read, and foundation crack repair covers the walls. See the Seattle Top Foundation Repair home page for all services.
What changed, and roughly when? A sloping floor, a door that no longer closes, a crack? We'll get back to you soon with an estimate or any questions we have. Estimates are free and there's no obligation.
Call (206) 717-8636