Foundation Underpinning in Montgomery, AL

Foundation underpinning is the process of strengthening and stabilizing an existing foundation

by extending it deeper into competent soil or bedrock. In Montgomery, Alabama, where

expansive clay causes shallow foundations to move, foundation underpinning is often the only

permanent solution to settlement problems. This article explains the most common

underpinning methods and when they are needed.

Understanding Why Underpinning Is Necessary

A foundation that rests on Montgomery’s red clay is only as stable as the moisture content of

that clay. During droughts, the clay shrinks, and the foundation settles. During wet periods, the

clay swells and can lift the foundation. Over years of this cycle, the soil loses its bearing

capacity, and the foundation sinks progressively. Underpinning bypasses the problematic clay

entirely by transferring the building’s weight to deeper, non‑expansive soil layers or bedrock.

Once underpinned, your foundation no longer responds to seasonal moisture changes.

Montgomery Foundation Repair Co has completed hundreds of underpinning projects across

the River Region.

Push Pier Underpinning

Push piers (also called resistance piers) are the most common underpinning method for slab

foundations. Steel pipe sections are hydraulically driven through the unstable clay until they

reach a dense bearing layer. The pipes are then locked to the foundation with steel brackets,

and the foundation is lifted back to level. Push piers work well for two‑story homes, brick

exteriors, and any heavy structure. Installation takes two to four days, and the piers are hidden

underground once backfilled. Montgomery Foundation Repair Co uses only galvanized steel to

prevent corrosion over the decades.

Helical Pier Underpinning

Helical piers are similar to push piers but are screwed into the ground rather than driven. This

method produces no impact vibration, making it ideal for homes with delicate finishes or for

underpinning interior footings where access is limited. Helical piers also provide immediate

load capacity, and the torque required during installation gives real‑time feedback on soil

strength. They are often used for pier‑and‑beam foundations, porches, garages, and additions.

Montgomery Foundation Repair Co selects helical piers when working in tight crawl spaces or

when the bearing layer is shallow enough to be reached with moderate‑length shafts.

Concrete Pier Underpinning

An older method, concrete pressed piles or poured concrete piers are still used in some

situations. Concrete piles are formed by excavating a hole, pouring concrete, and allowing it to

cure. This method is less expensive for very shallow underpinning (less than 10 feet), but it has

drawbacks: concrete takes days to gain strength, and the piers can crack if the clay swells

around them. For most Montgomery underpinning projects, steel piers are superior because

they are installed in hours rather than days, they can reach greater depths, and they are not

affected by soil movement. Montgomery Foundation Repair Co uses concrete underpinning

only for very specific, shallow applications.

Frequently Asked Questions