Some foundation problems are about water. This one is about movement. When the soil under your home cannot hold its weight, part of the house starts to sink. Doors stick, floors slope, cracks open in a stair-step pattern. Foundation piers — also called underpinning — are steel supports driven deep into the ground to reach soil strong enough to hold your home steady. This page explains how they work and when a house needs them.
What it means when a house is settling
All houses settle a little in the first years after they are built. That is normal. Problem settling is when one part of the house sinks faster or deeper than the rest. The signs are hard to miss once you know them: diagonal cracks above doors and windows, floors that slope or feel uneven, gaps where the wall meets the ceiling or floor, a chimney pulling away from the house, or doors and windows that used to work fine and now stick.
In Charles County, settling often traces back to the soil. Clay soil shrinks during dry spells, which can leave parts of the foundation unsupported. Poorly compacted fill dirt under newer homes can compress over time. And in some areas, the original footing simply was not placed on soil strong enough for the weight above it. A little even settlement in a new home is usually normal. The warning signs are uneven movement: diagonal cracks, floors that slope in one direction, and gaps that keep growing.
How piers work
A pier is a steel column that connects your foundation to deep, stable soil or bedrock. The foundation is exposed at intervals around the sinking area, a steel bracket is attached to the footing, and the pier is driven down through the bracket until it reaches soil strong enough to support the house. Then hydraulic equipment lifts the foundation back toward its original position, and the weight of the home is transferred onto the piers.
The key idea is simple: the surface soil failed, so we go deeper. A few feet down, the soil that caused the problem is bypassed entirely. The home ends up resting on piers anchored in ground that will not move. For a fuller picture of the repair process, see how foundation repair works.
Push piers vs helical piers
There are two main types of piers. They solve the same problem in different ways, and the right choice depends on your soil and your home.
Push piers
Push piers, also called resistance piers, are steel tubes driven straight down by hydraulic pressure. They use the weight of the house itself as the force that pushes them into the ground. They keep going until they hit refusal — the point where the soil is strong enough that the pier will not go deeper. Push piers are the most common choice for heavy homes on settling foundations because they can reach very deep, stable layers and they are load-tested during installation: the installer knows exactly how much weight each pier can carry.
Helical piers
Helical piers look like giant screws. They have steel plates (helices) welded to the shaft, and they are rotated into the ground like a screw into wood. The installer measures the torque as they go, which tells them when the pier has reached strong soil. Helical piers are often used for lighter structures, porches, additions, and chimneys, and for new construction where the soil is known to be weak. They can also be installed in tighter spaces and do not rely on the weight of the structure to drive them.
Both types are permanent. Once installed and load-tested, they become part of the foundation. The choice between them comes down to soil conditions, the weight of the structure, and access — which is exactly what an inspection determines.
How many piers a home needs
There is no standard number. It depends on how much of the foundation is settling and how far the weak soil extends. A sinking corner might need a few piers. A whole side of the house might need many. Piers are typically spaced several feet apart along the affected area. A real plan comes from measuring the settlement across the foundation — where it has dropped, by how much, and where it is still stable. Anyone who quotes you a pier count without measuring is guessing.
What installation looks like
Pier installation is done from outside the home in most cases. Small sections of soil are dug out at each pier location to expose the footing. The bracket is attached, the pier is driven, and the foundation is lifted slowly and carefully — usually a little at a time, watching for how the house responds. The holes are backfilled when done. Most homes take a few days. You can stay in the house during the work. Landscaping around the work areas gets disturbed, but a careful crew restores the grade when they finish.
Lifting is done gradually on purpose. The goal is to stabilize the foundation and recover as much of the original position as possible, not to force the house back in one push. Some interior cracks may close up as the house lifts. Others may need cosmetic repair afterward — a small price for a stable foundation.
After the lift, the crew backfills each excavation, compacts the soil, and restores the grade so water still flows away from the house. Final measurements are taken to document the new elevations, and you get a copy for your records. Those numbers are your proof the foundation is stable — and they are valuable if you ever sell the home, because they show a buyer the work was measured, not guessed at.
When settling needs a structural engineer
We believe in being straight about this: some settling situations should involve a licensed structural engineer, not just a repair contractor. If the settlement is severe, if the cause is unclear, if you are buying or selling the home, or if a previous repair has failed, an engineer's report gives you an independent diagnosis and a repair plan that any contractor can bid on. It protects you. We will tell you honestly during an inspection when we think an engineer should be involved before work begins.
Free inspection for settling foundations
If your home shows the signs — sloping floors, stair-step cracks, sticking doors — the first step is measurements. Our free inspection maps where your foundation has moved, explains what is causing it, and gives you a written plan and quote. If the fix is piers, we will show you why. If it is something simpler, we will tell you that instead. Fill out the form below to get started. For a sense of what drives the price, see our guide to foundation repair costs in Maryland, and if you are weighing piering against a full replacement, read foundation repair vs replacement.