Types of Foundation Repair Methods: A Detailed Guide

When it comes to foundation issues, addressing them promptly is crucial for maintaining the integrity and value of your home. In Denver, where the soil can be especially tricky due to expansive clay, foundation problems are relatively common. But how do you know which foundation repair method is right for your home? With several techniques available, it’s important to understand your options.

This detailed guide will walk you through the most common foundation repair methods, including underpinning, helical piers, crack repair, and waterproofing. Whether you're dealing with minor issues or extensive damage, knowing which method best addresses your specific needs can help ensure your home’s stability for years to come.

1. Underpinning: Strengthening Your Foundation’s Base

Underpinning is a technique used to stabilize and strengthen a foundation. This method is often necessary when the soil beneath your home has shifted or weakened, causing the foundation to sink or settle. Underpinning is a critical solution when the existing foundation can no longer support the weight of the home or is not positioned deep enough into stable soil.

How Underpinning Works

Underpinning involves extending the foundation’s reach deeper into the ground, often to a layer of soil that’s more stable with the goal of creating a solid base that prevents further settling or movement of the foundation. In almost all cases, modern underpinning involves advancing a pier through unstable layers of soil to stable bedrock. There are a few common methods of advancing a pier to depth; the effectiveness of the method depends on the characteristics of the soil the pier needs to penetrate before reaching quality bedrock.

When Is Underpinning Necessary?

Underpinning is most commonly used when:

• There are signs of significant settling or sinking.
• The foundation is no longer level.
• The property has undergone changes that affect the stability of the soil, such as nearby construction or poor drainage.
• The foundation has been poorly designed or constructed from the outset.

2. Helical Piers: A Modern Solution for Foundation Repair

 

Helical piers are one of the most modern and effective solutions for foundation repair, especially in areas like Denver with expansive clay soils. Helical piers are just big soil screws. Using a specialty, high-torque hydraulic motor driven by heavy excavation equipment (skid-steer or excavator). Typically a helical pier will have just one screw plate at the tip of the leading end of the pier. With rotation, the helical bites into the soil and begins to advance through the soil like a wood screw through wood. As we advance the helical, we carefully monitor the depth, the rate of advancement into deeper soils, and the torque required to screw the helical deeper into the earth. Just as it takes more effort to put a wood screw into oak than it is into pine, it requires more torque to advance through denser soil than it does through softer soil. VMC uses the best torque gauges available to carefully infer the bearing capabilities (strength) of the soil the helix is embedded into and continues to screw the helix deeper until it reaches sufficiently dense soil to support the structure. VMC uses only American-made Chance/Hubble helical piers and applies a 2x factor of safety when installing all helical piers.

Once the helical piers are installed, they are attached to the foundation with lifting/support brackets, the building’s weight is transferred through the piers and onto the deep, stable soil the helix is embedded into, and the structure is re-leveled.

How Helical Piers Work

This method is minimally invasive and can be done with little disruption to the surrounding area, making it an ideal solution for homes with limited access or landscaping.

When Are Helical Piers Used?

Helical piers are an excellent choice for homes with moderate to severe foundation issues caused by settling or shifting soil. Helical piers are fantastic where soil conditions are right. They are commonly used when:

• The foundation is experiencing uneven settling.
• Expansive soil has caused the foundation to move.
• Pier and beam foundations are sinking and need extra support.
• The property is in an area with soft, unstable soil near the surface, with denser soil deeper than the normal water table, like many neighborhoods in Denver.

Helical piers install quickly, without a lot of noise or other disturbances

When are Helical Piers NOT a good solution to foundation movement?

Rocky Soil:

Helical piers are great at screwing through soil, but rocks will stop them. If your soil is rocky, it may be impossible to advance the helix to suitable soil.

Dense, but expansive soil near the surface: there are many places on the front range where the soil is dense AND expansive. Expansive means that the soil contains clay minerals with a high attraction to water. When wet, these soils expand, growing in volume by as much as 15% with thousands of pounds of force. When dried, these soils often return to their original volumes.

These shallow, expansive soils, typically claystones, can be too dense to advance a helix through. VMC uses the most powerful installation equipment available, but even with 10,000 foot-pounds of torque, claystone can be impossible to penetrate. If the helix of the pier is not deep enough, or is embedded into soil with fluctuating moisture content, helical piers are probably not the right solution for the repair.

Micro-piles:

When Helicals won’t work, it's micropiles to the rescue. When difficult soil conditions or rocks make helicals the wrong choice, micropiles will stabilize your structure. A micropile drill is potent technology, capable of hammering through the toughest rock, so that we can get down to stable bedrock no matter the depth or obstructions in the way. With a micropile, we drill a relatively narrow hole (typically 3”-4” diameter) deep into bedrock, grouting a continuous, large diameter (1-1/8” to 2-1/8”) bar extending from the bottom of the hole to the bedrock. The grouted micropile is then attached to the foundation bracket in a very similar fashion to the helical pier, and the structure is stabilized/leveled.

Micropiles require careful engineering and knowledge of your soil conditions. Installation is comparatively slow, expensive, and dirty. We don’t recommend micropiles where helical piers are effective, but micropiles are the gold standard in foundation repair. Van Matre Construction has tested dozens of micropiles up to 200,000 lbs. and has installed hundreds and thousands of them along the Front Range with no failures. If your home is in Candelas, near the mountains, in the greater Erie area, or in many other areas, helical piers could be a bad choice.

Push Piers or Friction Piers:

Push piers are typically 2-1/2” to 4” open-ended pipe sections that are hydraulically ‘pushed’ into the soil. To install a push pier, a bracket is installed at the base of the foundation. The bracket has a hydraulic cylinder that, using the weight of the structure as a counterbalance, pushes the pipe into the earth until the friction between the pipe and the soil is enough to balance the weight of the house. Push piers are cheap, and they go in fast. It is really a shame that they won’t go through rock or stiff, shallow, expansive soil. It is difficult to install push piers with much more force than the weight that the piers will ultimately support. Push piers would be great for soft, non-expansive soils overlaying hard, non-expansive soils. Sadly, those ain’t the soils we have on the front range and it is why Van Matre Construction does not install push piers. They may be ‘cheap’ in comparison with helical piers or micropiles, but they are still far from inexpensive. The structure that needs repairing is also far from inexpensive. Don’t go cheap with your biggest investment. If it needs repairing, it is worth doing it right. Van Matre Construction will never install an inferior product.