What Is Foundation Underpinning?
Sloped floors. Sticking windows. Cracked walls. These are all signs that a building’s foundation may be sinking or settling. And if a structure has foundation problems, the issues need to be addressed quickly before more damage occurs. One possible solution is foundation underpinning.
Foundation underpinning is a construction technique used by Alliance Inc. to strengthen and stabilize the foundation of a building or structure. It involves adding support or reinforcing the existing foundation to prevent settling, sinking, or structural damage.
When Is Foundation Underpinning Needed?
Underpinning is typically used in the following situations:
- Foundation Settlement: When a foundation settles unevenly, causing cracks or structural issues in the building.
- Foundation Damage: If the foundation has been damaged due to soil movement, water damage, or other factors.
- Increasing Load-Bearing Capacity: To increase the load-bearing capacity of the foundation for additional stories or heavier structures.
- Changing Foundation Design: When modifying or adding to an existing building’s foundation design.
Signs That You Need Foundation Underpinning
If you notice any of the following warning signs in your home, it may be time to have your foundation evaluated by a professional:
- Cracks in Walls: Look for vertical or diagonal cracks, especially near corners, windows, and door frames. Stair-step cracks in brick or block walls are also a red flag. While small hairline cracks aren’t always cause for alarm, cracks that are widening over time warrant attention.
- Uneven or Sloping Floors: If your floors feel like they slope or bounce in certain areas, it could indicate that the soil beneath your foundation is shifting or settling unevenly.
- Sticking Doors and Windows: When a foundation moves, it can cause door and window frames to fall out of alignment, making them difficult or impossible to open and close properly.
- Sagging or Uneven Ceilings: Visible dips or changes in ceiling height can signal that the structure above is being affected by foundation movement below.
- Foundation Cracks: Visible cracks in your foundation walls or floor — particularly horizontal cracks, which can indicate lateral soil pressure — should be evaluated promptly.
- Bowing or Leaning Walls: Walls that appear to be pushing inward or leaning outward are a serious warning sign that should not be ignored.
Foundation issues rarely resolve on their own — and they tend to get more expensive to fix the longer they go unaddressed. If you’re seeing one or more of these signs, contact Alliance Inc. for an evaluation.
How Does Foundation Underpinning Work?
At Alliance Inc., we use helical piers (also known as helical piles) to underpin and stabilize home foundations. Helical piers are steel shafts with helical plates welded along the shaft — essentially a large, heavy-duty screw that is driven deep into the ground until it reaches stable, load-bearing soil below the frost line. Here’s how the process works from start to finish:
- Foundation assessment: We begin by evaluating your foundation to understand the cause and extent of the movement, assess soil conditions, and determine how many piers are needed and where they should be placed. This step ensures the system is engineered to handle your home’s specific load requirements.
- Excavation: Small excavations are made at each pier location around the foundation perimeter, exposing the footing where the support brackets will be attached. Because helical piers require minimal digging compared to traditional underpinning methods, disruption to your yard and landscaping is kept to a minimum.
- Pier installation: Using hydraulic equipment, each helical pier is mechanically screwed into the ground until it reaches stable soil or bedrock well below the frost line. This is what makes helical piers particularly well-suited to Duluth’s climate — anchoring below the frost line means the piers aren’t affected by the seasonal freezing and thawing that contributes to foundation movement.
- Bracket attachment: A steel bracket is secured to the top of each pier and connected directly to your foundation footing. This is the critical connection point where the load transfers from your foundation to the piers.
- Load transfer and stabilization: Once the brackets are in place, the weight of the structure is transferred to the helical piers, bypassing the unstable soil that was causing the problem. In some cases, we are able to partially lift the foundation back toward its original position.
- Site restoration: Excavated areas are backfilled and the site is cleaned up. Most homeowners are surprised by how little disruption the process involves. And because helical piers bear load immediately (no curing time required), the job is typically complete in one to three days.
Concerned Your Foundation Is Settling?
Don’t ignore signs of foundation issues. Contact the foundation experts at Alliance Inc. to schedule your appointment. You can also call us at 218-591-8039 or send us a text. See why we’re Duluth’s foundation repair and basement waterproofing specialists.
Frequently Asked Questions About Foundation Underpinning
The most common causes are soil movement, erosion, or settling beneath the foundation — often accelerated by water infiltration, tree root activity, or the freeze-thaw cycles common in northern climates like Duluth. Older homes built on inadequate foundations, or homes that have had additions added over time, may also develop the need for underpinning as load demands increase.
Underpinning is one method of foundation repair, but not all foundation repair involves underpinning. Underpinning specifically refers to extending or reinforcing the foundation to reach more stable soil deeper in the ground. Other foundation repair methods address cracking, bowing walls, or water intrusion without necessarily underpinning the foundation itself.
The timeline depends on the size of the home and the number of piers required, but most residential underpinning projects can be completed in one to three days. Because Alliance Inc. uses helical piers — which are screwed into the ground rather than poured — there’s no curing time, and the foundation can bear load immediately after installation.
When properly engineered and installed, helical pier underpinning provides a long-term solution. The piers are driven below the frost line and into stable load-bearing soil, so they aren’t affected by the seasonal movement that causes foundation problems in the first place.
Cost varies based on the size of the affected area, the number of piers needed, and the soil conditions at your property. It’s difficult to give a meaningful estimate without assessing the foundation directly. Contact Alliance Inc. for a free evaluation — we’ll give you a clear picture of what’s involved and what it will cost.
In most cases, yes. Helical pier installation involves minimal excavation and disruption compared to traditional underpinning methods, and the work is typically completed within a day or two. Our team will walk you through what to expect before work begins.