How to Reinforce a Sinking Foundation

Expose the bottom of the foundation. Most foundation work requires excavating equipment that produces access to the lowest part of the foundation, or the footings. It is at this lowest part of the foundation to which the piers will eventually be bolted. Some more minor reinforcement jobs can dispense with digging altogether and just drill the pier into the soil. The pier can be bolted to the outside of the home. For more severe foundation sags, it is always a good idea to expose the entire foundation.

Decide on a proper torque level. This refers to the amount of pressure that house requires to be kept from sinking again. This depends on the size of the house and the amount of foundation footage that is sinking into the soil. Normally, a pier's maximum capacity is 10,000 lbs. A large, multistoried house, especially those made of brick, require many piers brought to, but never exceeding, their maximum capacity. An expert should be consulted to give some estimate as to how many piers are required. Many foundation consulting firms exist that can give professional estimates on these issues and help you avoid having foundation repair firms sell you more piers than you actually need.

Drill several metal piers into the soil. For the parts of an average house that has a sinking foundation, four or five metal piers are normally sufficient. It is always a good idea to check with an expert to ensure you are using sufficient support. Piers are normally about 5 feet in length, but for soils that are particular poor, extendable piers are available.

Stop drilling once resistance has been reached. Many pier systems have a torque meter attached to the pier itself that gives an indication when more solid ground has been reached. The maximum required torque is usually 20,000 lbs. of pressure, which is more than sufficient to keep even large structures from sinking into the ground once they have been leveled. Always keep the pier close to the foundation wall, almost touching. The pier itself has threads like a screw, which provide extra support and place the pier firmly in the soil. These threads are called helices, the plural for helix, and the pier then called a helical pier. The helices allow for a better fit of the metal bar into the soil.

Bolt the pier into the foundation wall. Normally, this is done at the lowest point. Most, if not all, helical pier systems come with the bracket and bolts that then are driven into the concrete. This will keep the pier attached to the foundation and prevent it creeping upwards.