Underpinning a home's foundation is often needed if the foundation is damaged and cannot be fixed through sealants and other materials that simply cover over or fill in cracks and chips. Underpinning also gives the foundation added strength to better hold up your home and avoid shifting and sinking. If you've been told that your home needs underpinning or if you know your home is shifting due to soft soil or structural damage, note a few questions you might have about this process and discuss these with a contractor as necessary.
If I'm planning on renovating when should I have the foundation underpinned?
You should have your home's foundation underpinned or fixed however necessary before you handle any renovation work, including work outside. The home should be level and even before you tear down or put up walls, install windows, and the like so that these are installed evenly. Note that your home's walls, floors, and ceilings could also crack at any time if the foundation is not level, so your renovation work could be ruined if the foundation is not fixed first.
For outside work, you want to underpin the foundation before landscaping, installing underground sprinklers, or installing any outbuilding. This will give the contractor time to note if there is water collecting around the home's foundation that is causing damage and, if so, whether or not your property needs a retaining wall or to be graded to fix this problem. Grading the property or installing a retaining wall may affect your landscaping design or where and how you erect an outbuilding, so any work on your home's foundation should come before this other work on your property.
Is actual underpinning the only option for fixing the foundation?
Some underpinning methods will involve actual pins that are set underneath the foundation to brace it up. However, other methods are not quite as involved. A contractor may pour a second layer of concrete to adhere to your home's foundation to make it thicker. If your home has timber stumps, these may be replaced by steel stumps so they're stronger and more durable. Another method will involve attaching beams or boards to the foundation to keep it from cracking.
If you're concerned about your budget or the time involved with underpinning, ask your contractor if he or she can offer you some options for how to address the exact problems with your home's foundation. You should be able to find a solution that's workable for you and appropriate for the construction of your home in particular.