Foundation Repair in Doney Park, Arizona

Foundation repair in Doney Park is cinder work. This is the part of Coconino County where the volcanic material is thickest and least reliable to build on, and where the difference between one lot and the next can be dramatic.

Doney Park is a census-designated place northeast of Flagstaff, sitting at about 6,555 feet along US Route 89, with most homes on lots of an acre or more. It is known for its views of the San Francisco Peaks and Sunset Crater — and those views are the clue. You can see the volcano from your porch because you are sitting on what it produced.

Sunset Crater put this ground here

Sunset Crater erupted roughly a thousand years ago, which is extraordinarily recent in geological terms, and it blanketed the country northeast of Flagstaff in cinder and ash. Doney Park is in that blanket. The material has had a thousand years to weather, which is not very long, so it has not developed into structured soil the way older deposits have.

Cinder has properties that make it a poor bearing material. It is porous and lightweight, full of air voids, and it compresses under sustained load. It drains extremely fast, which sounds good but means water moves through it at speed, and moving water carries fine material with it. A footing bearing on cinder is bearing on something that consolidates over decades and can be physically eroded from beneath in a single wet spring.

The depth to competent material also varies enormously across short distances out here. One corner of a house may reach basalt at five feet while the opposite corner has fifteen feet of cinder underneath it. That is a differential settlement machine.

Acre lots change the problem

Most Doney Park properties are large, which affects foundations in ways people do not expect.

Private wells and septic

Nearly everything out here is on a well and an on-site septic system. A leach field is a continuous water source in one part of the property. A leaking well line or pressure tank line is a slow, sustained water input that erodes cinder efficiently. When we find settlement concentrated on one side of a Doney Park house, water lines and septic are among the first things we want ruled out.

Long driveways and disturbed ground

Big lots mean long driveways, buried utility runs, and a lot of grading. Every trench is a channel that water will preferentially follow, and around here trenches were often backfilled with the cinder that came out of them, which does not compact well.

Owner-built additions

Rural acreage attracts people who build things themselves. Shops, additions, carports, and decks get attached to houses with foundations that were never engineered. Where an unengineered addition meets an engineered house, they move separately and the joint cracks.

Manufactured homes

Doney Park and the adjacent Timberline and Fernwood areas have a large population of manufactured homes on permanent foundations. These have specific requirements in Coconino County, including footings that reach the frost line. County policy is explicit that frost-protected shallow foundations are not permitted for manufactured home crawlspaces here, because a crawlspace cannot maintain the required minimum temperature.

The failure pattern on a manufactured home is different from a site-built house. Instead of a continuous footing settling, you get individual piers settling at different rates. The result is a floor that develops waves rather than a single slope, doors that bind in one part of the home and not another, and marriage-line separation on double-wides. It is very fixable, and it is often the least expensive foundation work we do — as long as it is caught before the frame gets stressed.

Freeze-thaw out here

At 6,555 feet Doney Park gets the full high-country freeze-thaw season, and the 30-inch Coconino County frost depth applies. Cinder's saving grace is that it drains so freely there is often less water held in it to freeze. Where cinder gives way to finer material or where drainage is poor, heave becomes a real factor.

What we check in Doney Park

• Elevation readings, and on manufactured homes, individual pier heights.
• Depth to competent bearing, verified rather than assumed.
• Well line and septic position and condition.
• Where the driveway and site grading send runoff.
• Snow storage location, which on an acre lot is often solvable simply by choosing a different spot.
• Additions and outbuildings and how they connect.

Permits

Doney Park is unincorporated, so Coconino County handles permits, and the county maintains a Doney Park, Timberline and Fernwood area plan. Structural work generally requires a permit. Arizona contractor licenses can be verified free at roc.az.gov.

Nearby work

• Mountain View Ranches
• Fort Valley
• Bellemont
• Underpinning
• Sinking foundations
• All service areas