Typical cost in Sammamish
When a house settles, floors slope, doors stop closing and cracks open at the corners. Sammamish Foundation Repair looks at whether the foundation is moving, why, and whether piers are the right tool, without promising that a house can be lifted back to level.
We cover Sammamish, Issaquah and Fall City. Sammamish stock is recent, with 1994 as the median year built, so a settling house here raises questions about the ground the house was built on and the water around it.
Floors that slope toward one corner, doors and windows that stick or show a wedge-shaped gap, cracks running from the corners of openings, and a gap between a wall and the floor are things people notice. On their own none of these proves settlement, because framing moves with the seasons too. A marble, a level and photographs taken over several weeks give a better record than a single look.
HUD lists the primary causes of foundation failure as difficult sites, poor soil, seismic activity, water moving through soil or flooding, and poor design or materials. For soil it names highly expansive soil, organic or silty soil, and fill that was compacted poorly and not laid in layers. HUD adds that settlement happens over time, not as an abrupt event.
Washington DNR’s Bulletin 78 reports expansive clays only in limited, isolated pockets around Puget Sound, and places the majority of peat deposits, which settle heavily under load and drying, in the Puget Sound basin. Neither fact says what lies beneath a particular lot; a soils investigation does.
HUD cautions that a mini-pier used wrongly can crack the foundation and slab, and that it is economical only where a bearing layer is relatively near grade. The pier itself is a 2 to 8 inch steel pipe, driven hydraulically beside the footing to rock or adequate bearing strata, with the weight of the building supplying the resistance.
A helical pier is a steel shaft carrying helical plates that is turned into stable soil and connected to the footing with a bracket. Per HUD, it fails where soils have limited bearing capacity, and the torque needed to install it can be measured to find out the capacity actually achieved. The soil investigation informs which system suits the ground.
Neither system is promised to raise a house. For augered reinforced concrete piers, HUD says lifting a foundation more than a few inches is hard in sandy soils. Settlement repair here means putting a footing on better ground, and whether any lift is possible is for the engineer and the soil to say.
HUD wants the cause of settlement examined by a structural or geotechnical engineer, repairs carried out by experienced contractors directed by a professional engineer, and any underpinning by footing enlargement designed by an engineer. Those are federal recommendations, not Sammamish rules.
Foundation repair is not among the exempt examples on the regional MyBuildingPermit tip sheet, which lists Sammamish as a participating city, so treat a permit as a question to settle with the Permit Center. The city’s summary sheet describes seismic hazard areas as susceptible to liquefaction on the King County map and says development proposals in them must include a geotechnical report. WAC 365-190-120 describes settlement and liquefaction as occurring in low-density cohesionless soils, usually with a shallow water table. Ask the Permit Center what applies at your address.
Washing fines out from beneath a foundation reduces soil cohesion and causes settlement, HUD says. Piers set in soil that keeps eroding can leave the problem in place, which is why the foundation drainage page matters here.
Piering is priced from the ground and the house, and the factors are:
This site does not promise that. Piers carry a footing on deeper ground, and how much a house moves depends on the soil and the structure. An engineer’s report sets what is realistic.
Photographs and measurements over time help, such as marking the ends of a crack with dates. HUD’s guide says settlement usually happens over time, so a record kept for a few weeks tells more than one look.
HUD’s guide says repairs should be done under the direction of a professional engineer, and the city may require reports in some hazard areas. Whether your project needs one is a question for the Permit Center and for the engineer you consult.
Cracks that formed as the footing moved are dealt with on the foundation crack repair page, while soil that keeps washing away from the footing is a foundation drainage matter. The Sammamish Foundation Repair home page puts the four services in one place.
Describe what you see: sloping floors, door gaps or cracks, and where in the house. Say whether it has changed in the last year or so, whether there was recent work on the lot, and whether you have an engineer’s or geotechnical report. We'll get back to you soon with an estimate or any questions we have. Estimates are free and there's no obligation.
Call (425) 642-1026