If you have been given an estimate that mentions piers, you have probably heard both
terms. Push piers and helical piers do the same fundamental job. They carry the weight of
your house past the soil that is causing the trouble and set it on ground that will hold.
What differs is how each one gets down there, and that difference is what decides which
belongs under your house.
How a push pier works
A push pier is driven straight down using the weight of the structure itself as the
resistance. We expose the footing, set a concrete cylinder six inches across and twelve
inches long into the hole with a powered ram on top and a titanium plate bracing the
footing, and drive it down. Then we feed number four rebar through the cylinder and drive
the next one in behind it. We keep going until the pier builds enough pressure to stabilize
the wall.
Because the house itself provides the resistance, there is no fixed depth. The ground
tells you when you have gone far enough rather than a specification deciding it in advance.
That is a real advantage in East Tennessee, where the depth to stable soil can change from
one side of a lot to the other.
How a helical pier works
A helical pier is turned into the ground like a large screw. Helical plates welded to
the shaft pull it down as it rotates, and the installer measures the torque it takes to
turn it. That torque reading correlates to load capacity, so the pier can be verified as it
goes in rather than by pushing against the building.
The important consequence is that a helical pier does not need the structure to be heavy.
It generates its own capacity.
The practical difference
| Push pier | Helical pier | |
|---|---|---|
| Driven by | Weight of the structure | Rotation and torque |
| Best suited to | Heavier structures, full houses | Lighter structures, additions, porches, decks |
| Depth | Determined by resistance as it drives | Determined by torque as it turns |
| Needs building weight | Yes | No |
So which one do you need?
It comes down to what is being supported and what is underneath it. A two-story brick
home has plenty of weight to drive a push pier against, and a push pier suits it well. A
sunroom, a porch, or an addition on a slab may not weigh enough to drive against, and a
helical pier handles that situation without needing the mass.
There is a third possibility worth mentioning. When the goal is a controlled lift under
an existing footing, an under footing bracket system such as the Atlas Resistance pier is
engineered for lifts of up to four inches, in diameters from two and seven eighths up to
four and a half inches, with capacities from thirty to seventy and a half kips.
We look at the structure, the soil, and the access before recommending any of them. The
inspection and the written estimate are both free.
Common Questions
Is one type stronger than the other?
Neither is stronger as a category. Capacity depends on the pier size and the soil it lands in, not on which installation method was used. A properly sized helical pier and a properly sized push pier can both carry more than a house puts down. The right question is not which is stronger but which suits the structure and the ground.
Which one costs less?
That varies by job rather than by type. Depth to stable soil, how many piers the structure needs, and how much access we have all move the number more than the choice of pier does. This is why an estimate has to come from looking at the actual house.
Can either type lift my house back up?
Both can recover settlement in many cases. How much lift is achievable depends on how far the house dropped and what the structure above will tolerate without cracking finishes. Sometimes the correct answer is to stabilize where the house sits rather than force a lift.
Do piers need maintenance after installation?
No. Once a pier is set on stable soil and the load is transferred, it is doing its job passively. What is worth maintaining is the drainage around your foundation, because water is what caused the movement in the first place.
Call us at (865) 675-4177 and we will talk through what you are seeing. The inspection and the estimate are both free.