Ann Arbor Foundation Pros: Helical Piers, Bowing Wall Repair & Foundation Crack Repair

When a block wall has pushed in too far to brace, or a stone wall is falling out of its mortar, the lasting fix is a new wall. The crew digs the outside down to the footing, shores up the floor framing, takes out the failed section and lays new block with rebar and grout in the cells, or forms and pours concrete. Then the outside face gets waterproofed, drain tile goes in beside the footing, and the trench is backfilled. Michigan's code calls for a drain around basement foundations, with gravel reaching at least a foot past the footing and six inches above it, and for the finished grade to fall 6 inches within the first 10 feet of the wall.

It's the biggest job on this page, and the only one that ends with a new wall rather than a braced old one.

See Basement Wall Replacement in Ann Arbor, MI.

Piers carry a settling house down through soft or wet soil to ground that can hold it. Push piers are steel tubes driven in sections by a hydraulic ram that uses the house's own weight to push against, which suits heavy two-story masonry. Helical piers have steel plates welded to the shaft and are screwed in. The torque at the drive head tells the installer what the pier will carry: capacity is torque multiplied by a factor for that shaft size, with a safety factor of at least 2. Shafts are galvanized steel tube.

Michigan footings already sit 42 inches below grade, so pier work starts deep. Porches, additions and decks usually go helical. Once the piers are set, the footing is lifted back toward level, as far as the plaster and drywall above can take without cracking.

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A horizontal crack running along a block wall a few courses below grade means the soil outside is pushing the wall in. Home inspectors treat it as a sign the wall is bent or failing under that load. Steel I-beams stand against the inside face, fixed to the floor framing at the top and to the slab at the bottom. Some brace systems can be tightened in stages over several seasons. Wall anchors run a steel rod through the wall to a plate buried out in the yard and are tightened from inside, so they need open ground on that side. On a narrow lot with a driveway or the neighbor's house close by, braces fit where anchors can't.

The City of Ann Arbor requires signed and sealed drawings for basement wall reinforcement, so an engineer's drawing is part of the job.

See Bowing Basement Wall Repair in Ann Arbor, MI.

Carbon fiber straps are bonded to the wall face with epoxy every few feet and anchored at the top to the framing. They're thin, they hold a wall where it is, and you can frame or paint over them later. They won't push a wall back, and makers set a limit on how far a wall can have moved before straps are allowed. Past that limit, the choice is braces, anchors or a new wall.

See Carbon Fiber Straps for Basement Walls in Ann Arbor, MI.

Sloping or springy floors usually come from the framing under them rather than the foundation walls: a center beam that's undersized or rotted, posts sunk into a thin slab, joists notched for old plumbing. The repair is steel adjustable posts on new footings, a sistered or replaced beam, and jacking a little at a time. Michigan's code doesn't count work on load-bearing supports as an ordinary repair, so it needs a permit. A floor survey with a laser level first shows whether the low point is in the framing or in a footing that settled.

See House Leveling in Ann Arbor, MI and Sagging Floor Repair in Ann Arbor, MI.

Cracks in poured walls are injected from inside through ports set along the crack. Epoxy bonds the two sides and is the choice for a crack that has stopped moving. Polyurethane stays flexible and expands to fill the gap, which suits a crack that still opens and closes with freeze-thaw. Hairline shrinkage cracks are normal in poured concrete, but once a crack opens past 1/8 inch, something other than curing caused it.

Block walls can't be injected because their cores are hollow. A cracked block wall gets sealed, and braced if it's moving.

See Foundation Crack Repair in Ann Arbor, MI.

The city's historic district guidelines describe the 19th-century houses of the Ann Street district resting on fieldstone foundations. Those walls stand by their mass and soft mortar. Repointing them with mortar high in Portland cement is on the city's list of inappropriate treatments for soft historic masonry, because the hard mortar can't move with the stone. Block walls fail differently, with stair-step cracks along the joints, cracks through the block, and the horizontal crack described above. Repairs run from repointing and parging to rebuilding courses.

See Block Foundation Repair in Ann Arbor, MI and Stone Foundation Repair in Ann Arbor, MI.

Most basement floors are slabs poured inside the walls, not part of the structure, so a cracked floor is a separate problem from a cracked wall. A slab that heaves up in the middle points to water or clay swelling underneath. A slab that drops along the walls points to fill that settled. The repair is cutting out and repouring the section and sealing the joint at the wall, or lifting a settled slab with foam. If the floor rises again after every heavy rain, fix the drainage first; new concrete won't stay put.

See Basement Floor Repair in Ann Arbor, MI and Garage Floor Repair in Ann Arbor, MI.

A sunken driveway, garage floor, walk or patio slab can often be raised back into place instead of torn out. Polyurethane foam goes in through small holes, cures in about 15 minutes and is rated to last 10 to 15 years or more. Mudjacking pumps a heavier cement slurry through larger 1 to 2 inch holes, and that weight can cause more settling later.

See Concrete Lifting and Leveling in Ann Arbor, MI.

Ann Arbor gets about 38 inches of precipitation and 61 inches of snow in a normal year, and the water ends up in the soil against the basement. A single leaking crack in a poured wall gets injected. Seepage along the joint where the wall meets the floor usually needs interior drain tile: a channel beside the footing that carries water to a sump pit and pump. If the job adds a new discharge outside, it falls outside the city's expedited permit for basement waterproofing, which covers existing systems only.

See Basement Leak Repair in Ann Arbor, MI.

If you aren't sure what you're looking at, start here. An inspection measures crack widths, checks the walls for plumb and the floors for level, and looks at grading and downspouts. For a sale, an insurance claim or any bracing job, a structural engineer's report is the document that counts. HomeAdvisor puts one at $340 to $780 nationally.

See Foundation Inspection in Ann Arbor, MI.