Repair Methods guides

Repair methods, and when each is specified

Foundation repair is not one trade. It is a set of methods that solve different failures: a settled footing needs a pier, a settled slab needs lifting, a bowing wall needs restraint, and a wet crawl space needs drainage. The most common expensive mistake is buying wall anchors for a footing problem, or slab lifting for a structural settle.

Method	What it does	Specified for	Limit
Push piers	Steel shafts driven to bearing strata, bracket under the footing	Settled footings carrying structure	Needs exterior access; not for slab-only settlement
Helical piers	Screwed shafts with helical plates	Lighter loads, unstable or sandy soil, tie-backs	Lower capacity per shaft than push piers
Mudjacking	Slurry injected under a slab to fill voids and lift	Settled driveways, garage floors, patios	Heavy; may re-settle; not for structural footings
Polyurethane foam	Expanding resin injected under a slab	Slab, pool deck, interior floor lifting	Higher cost per sq ft; limited lift height
Carbon fibre straps	Epoxy-bonded straps across a wall crack	Cracked, lightly bowing block walls	Does not push a wall back; cosmetic crack remains
Wall anchors	Plates in the soil tied to wall brackets	Bowing walls, with outside access	Excavation; not for slabs
Slab lifting	Foam or slurry under an interior slab	Uneven floors, hollow spots	Does not fix the soil that caused it

Piers: how the choice is made

A push pier is driven down until it reaches bedrock or a stratum with enough capacity, then the weight of the house is transferred onto it. A helical pier is screwed in with a torque motor; the installation torque correlates with capacity, which is why the installer records it. Push piers generally carry more per shaft and are the default for a settled exterior footing on a house with a basement.

The number of piers is an engineering calculation, not a sales decision. A typical rule of thumb is one pier per 6–10 feet of affected wall, plus one at each corner of the settled area. A quote that lists "10 piers" without a plan showing where they go is a price, not a design.

Mudjacking and foam: lifting slabs, not footings

Both methods inject material through small holes in a slab. Mudjacking uses a cementitious slurry and is cheaper per square foot; polyurethane foam is lighter, cures in minutes and can be used where the slab is thin or the subgrade is unstable. Neither addresses the reason the soil moved, so both are maintenance rather than structural repair.

Where a slab is tied to a footing, lifting it without addressing the footing can crack the connection. That is why an engineer will sometimes specify piers first, then slab lifting — not the other way round.

Walls: restraint versus replacement

A horizontal crack in a block wall with slight bowing is a candidate for carbon fibre or anchors. A wall that has moved more than about 2 inches, or is bulging at mid-height, usually needs anchors with excavation and may need rebuilding. Carbon fibre stops movement but does not straighten the wall; any contractor promising a straight wall from straps alone is overselling.

The problems hub maps symptoms to tests, the cost hub carries unit prices, and the foundation types hub explains which failure belongs to which construction type.

Which is better, piers or mudjacking?

They solve different failures. Piers transfer structural load to bearing strata; mudjacking lifts a slab that has settled into a void. If the house structure is moving, piers; if a driveway or garage floor has dropped, lifting.

Do I need an engineer?

For structural work, yes — a stamped letter is what a permit office and a warranty claim will ask for. It costs $400–$1,500 and is cheap insurance against a $20,000 mistake.

How long does foundation repair last?

A properly designed pier system is intended to be permanent, and most carry a transferable lifetime warranty. Slab lifting and mudjacking are maintenance items that may need repeating in 5–15 years.