Underpinning is the process of strengthening the foundation of a home or building. If you are adding another floor to your home, if the original foundation is failing or if the soil structure has changed, you may need to consider underpinning. Regardless of why you need underpinning, here are some points you need to consider first.
1. Should You Rebuild?
Before you commit to underpinning, take some time to crunch the numbers. Underpinning can be a very involved process. In some cases, you may want to tear down your current home and rebuild. Crunch the numbers to ensure that you are making the best decision from a financial standpoint. You may want to consider other upcoming repairs that your existing home needs—remember, building a new home offsets those costs as well.
2. Can You Strengthen the Soil Instead?
If the soil is causing the issues with your foundation, you may be able to skip the underpinning and strengthen the soil instead. An underpinning expert or a soil analyst can give you advice. Generally, strengthening the soil involves adding structural resins to it. In some cases, you may also need to add extra drainage if the current moisture levels are causing too much expansion and contraction.
3. Should You Go Deeper or Wider?
Ultimately, if you decide to do underpinnings, you can go deeper or wider. That means, you can add pins that sit under your home and help to prop it up. They can take many forms, but to visualise this process, imagine concrete pillars being poured underneath the house. To add extra width to the foundation of your home, imagine long cross beams being added underneath it for more stability. There are a lot of factors such as soil structure, the current foundation of your home and budget considerations, that come into play when making this decision.
4. Can Mini Piles Work?
Also known as micro piles, pin piles, and needle piles, mini piles are very small underpinnings. This is especially helpful if there is a lot of rock under your home, as the piles don't have to go as deep. Before you commit to full size underpinning, you may want to see if this approach can work in your situation.
5. How Are You Going to Access the Area?
Finally, if you decide to move forward with underpinning, you need to decide how you are going to approach the project. Are you going to get into the crawlspace and hand dig? Are you going to have an expert handle everything? This is one of the last details you need to plan.