In construction or renovation, underpinning is the process of strengthening the foundation of an existing home or building. Underpinning may be necessary for a variety of reasons, but generally, the original foundation is no longer stable or strong enough. This may be the result of improper building in the first place, a change in the soil such as settling or lifting, or perhaps because an earthquake, flood, or other natural disaster has caused the building to shift.

What is Foundation Underpinning?

As indicated above, underpinning strengthens the foundation of a home or other structure. Underpinning may be necessary for a variety of reasons including changing the foundation depth, repairing a damaged foundation, or adding weight as in an additional story to the building. Foundation underpinning is cost effective, and far more economical than building a new structure.

How Does Foundation Underpinning Support Your Home?

Your home rests on its foundation. When the foundation is damaged, the building is stressed in ways it wasn’t built to withstand. When that happens, you may see large cracks, buckled walls, and windows and doors that no longer work properly. Additionally, parts of your home might actually shear away from the rest of the house.

Foundation underpinning increases the strength of the foundation and prevents further damage by increasing vertical support. Vertical support extends deeper into the soil beneath the building, thus adding strength and stability. Two methods of increasing vertical support are steel push piers or helical piers.

What Are Some Signs That You Need Foundation Underpinning?

Generally speaking, cracks are the signal your home may need foundation underpinning. Cracks wider than ¼” are sure evidence of foundation failure, especially if they are diagonal cracks or cracks in concrete floors. Buckled or cracked walls are more evidence your home could benefit from foundation underpinning.

What’s the Difference Between Steel Push Piers and Helical Piers?

Steel piers, also called push piers, are interlocking steel pipes that are rammed, hydraulically , into the earth, one pipe at a time. This continues until the piers reach a depth where the soil is strong and stable enough to be considered suitably load bearing. When the push piers are all installed, a hydraulic pump is attached to each. The house is then raised until it is level and the piers are then interconnected with cables.

 

Helical piers are also known as anchors, piles, or screwpiles, and they literally screw into the earth. There are two types, round and square shafted. Both are easy to install, require minimal soil disturbance, and are not affected by a high water table. As with push piers, these piers are installed to a depth where the soil is considered load bearing. Then brackets are attached to the wall bases so that weight is transferred to the anchors. This process may be best for larger, heavier repair projects.

Both methods have their pluses and minuses. Push piers cannot be used with light construction, as weight is needed to drive the piers. Helical piers cannot handle heavier construction and are apt to buckle under heavy weight. These work best with lighter construction projects.

As serious as the need for foundation underpinning sounds, it is not catastrophic. In fact, this type of home maintenance is fairly common. When you contact Atlas Piers of Atlanta, we use engineering data to determine how best to repair your foundation, and that often involves foundation underpinning. Give us a call today — we can help you prevent further damage to your home and pocket book.