How to Repair a Sunken Foundation


The settling and moving of a foundation originates with the construction of your home on expansive clay or soil that is compacted improperly. Another culprit is inadequate maintenance of soil around the foundation. The bottom line: such settling destroys the value of the home while affecting its structural integrity. Water is usually the basic factor causing soil issues. Certain elements within the soil shrink due to moisture, and such action varies considerably among types of soil, with soils high in clay content seeing the most shrinkage. The movement tends to vary as well, according to the concentration of soil elements, which then transfers to the foundation. A home will require the installation of a pier system to raise the foundation back to the proper level.

Things You'll Need

  • Excavating equipment
  • Hydraulic jacks
  • Support bracket
  • Guide sleeve
  • Starter section
  • Pier sections
  • Fastening plate
  • Shovel
  • Sledgehammer
  • Clear all shrubbery and remove concrete by breaking it up with a sledgehammer and removing with the shovel. Make a 3-foot by 4-foot excavation site next to the foundation at a depth of about 10 feet beneath the support beam. You may have more than one excavation site, depending on how many pier supports you need to install, to level the foundation.

  • Scrape the soil from the bottom of the footing with the shovel and chip the foundation gingerly, but uniformly, with the sledgehammer to allow the support bracket to rest snug with the foundation's support. Do this at each excavation site.

  • Place the piers underneath the support beam of your foundation at each excavation site. Install the support brackets to the foundation's support beam with the nuts and bolts that come with your chosen pier system, as designated for the support brackets. There are a variety of pier systems on the market and each one makes use of various nuts and bolts when affixing to the support beam. Refer to the user's manual for specifications and installation order.

  • Hook up the jacks and begin pumping until you feel resistance and the foundation begins to rise, then disconnect the hydraulics. Do this for each each pier installed. Once again, depending on the pier system chosen, the hydraulic jack will connect and disconnect from the pier support systems in a variety of ways. You will need to study your manual that comes with the pier support system to discern its unique set-up.

  • Install the fastening plates with the nuts and bolts provided, over the support beam at the top of the pier columns. Do not tighten the bolts yet, just loosely screw them in place. Your user's manual will specify which bolts are used for the fastening plates and their exact installation order.

  • Reconnect the hydraulics and begin pumping to elevate the foundation. Refer to the user's manual for reconnecting the jacks to your particular pier support system.

  • Raise the foundation to the determined height, then tighten down the fastening plates and support brackets on the pier columns.

  • Record for all piers the elevation, pressure and depth once the foundation is stable.

  • Put back and compact all excavated soil.

  • Replace all shrubs and concrete removed during excavation.

Tips & Warnings

  • Ascertain and fix the problems causing the foundation to sink in the first place. Cut off all supplies of moisture and, if needed, regrade the property to drain water away from the foundation.
  • During dry spells, water the soil next to the foundation with the aim of keeping the moisture content consistent with the soil underneath the foundation.
  • Signs of foundation issues appear inside the home as well. Doors and windows may not close properly. Sudden cracks may appear in the wall or the floors may be uneven, with cracking in the tiles. Be vigilant for such signs and enlist the help of a contractor immediately upon notice.
  • Pay attention to your water drainage for the air conditioning. Contractors and homeowners often overlook the impact of air conditioning drainage on sunken foundations. Make sure the water drains well away from the foundation.

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  • Photo Credit foundation steel. image by Greg Pickens from
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