Underpinning vs Deep Injection: Which Repair Method Is Best?

Underpinning vs Deep Injection: Which Repair Method Is Best?

At first, you notice a door won’t open. Then, cracks show up in the corners. “No worries, houses move all the time,” you think. Later, you notice the cracks are everywhere, one corner of the floor is sinking, and the front door is stuck. These are all common indicators of foundation settlement. When settlement becomes severe, you need to repair it to restore stability. In this article, we’ll go over two popular foundation repair methods, underpinning and deep injection, and discuss which of the two methods is better.

Underpinning Methods

Mass Pour

Mass pour is the most widely used method of underpinning.

Micro Piles

The micro pile method is best for sites where soil condition is varied and the access areas around the foundation are limited.

Beam and Base

The beam and base method is used when the existing foundation requires additional bearing load or when the existing footing has heavily deteriorated. This approach is most often used when construction is necessary below a structure on the same site.

Polyurethane Geotechnical Foams

Another method that offers additional support to a settled foundation is polyurethane foam slab lifting, or deep injection. Deep injection combines lightweight foams, cementitious material, or compacted soil (dirt). Deep injection has several practical applications for residential settlement issues.

Remedy Bad Soil

Deep injection reinforces or improves the load-bearing capability of the soil. It can also stabilize a location with bad soil.

Improve Compaction

If a building is already on the site, and the injection is needed to support the structure, a compaction test can verify when the necessary compaction has been reached.

Fill Voids

Because it is a lightweight material, deep injection can seep into crevasses and fill voids with ease.

Stop Material Erosion

If the worksite has gravel, a granular fill, or sandy soil, deep injection can lock this material in place.

Shallow Shoring

To build on the previous point of material erosion, deep injection can act as shoring during excavation. Let’s say you’re digging a trench several feet down, and the granular fill keeps running back into the hole. Deep injection “grabs” the granular material and makes a dam to solidify it, keeping it out of the excavated area. This makes it highly effective in granular or loose soil compositions, but it will not be effective in dense or heavily compacted soil. Deep injection may not be a good fit if a building has utilities that need maintenance, like ductwork or pipes.

Which Repair Method Is Better?

Underpinning and deep injection both have their merits, but you may not know which repair method is best. Determining which is best for you and your home would require a thorough investigation of the problems, causes, and your financial situation. Here are key questions to think about:

  • When did the settlement or foundation problems occur?
  • Is the problem worsening?
  • Did you stop the cause, or is the cause ongoing?
  • How much are you willing to invest to repair and/or arrest the problem?

With that in mind, it’s time to consult a foundation repair professional who understands what to look for and offers you enough information to make the best decision for your needs. In closing, we would like you to consider Foundation Technology as your trusted advisor. We can provide an effective, affordable solution for your foundation problems.