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Structural Foundation Repair: Interior vs Exterior Piers

Apr 16, 2015 • By Matthew Stock.

How to Permanently Repair a Sinking Foundation in Chicago

Structural foundation damage is one of the most serious problems that can happen to a home and, most often, a dropped or sunken foundation is the worst type of foundation damage.

A dropped foundation is caused by compaction of the soil below the foundation that should provide support.  Typically, this results from drought conditions that cause trees and large shrubs to send their root systems deeper and wider in search of water.  These roots will draw moisture from the soil below the foundation, leaving it desiccated and subject to compression or collapse.

When the support of the soil is withdrawn, the foundation drops to fill the void.  When this occurs, large cracks will develop in foundation walls and above ground and the foundation may actually separate from the home’s structure.

How to Repair Structural Foundation Damage Caused by a Dropped Foundation

The solution to a dropped foundation is really pretty simple in concept – raise it back to level and stabilize it there.  There are several methods of accomplishing this but the most effective is to use a system of hydraulic push piers to raise and support the damaged foundation.

The number and placement of piers is determined by conducting a thorough inspection of the damage and applying engineering principles to ensure that the load is fully supported.
Installing hydraulic push piers begins with excavating a small hole at the site of each pier, down to the level of the footings.  The exposed footing is notched and a steel bracket is permanently attached.

A hydraulic ram is then mounted to the bracket and used to drive sections of steel pipe into the ground until the column reaches a load-bearing stratum in the soil below.

After the piers have been driven to the appropriate depth, a hydraulic pump is attached to all piers and is used to slowly raise the foundation until it is once again level and all cracks have been closed.  While the foundation is held in place by hydraulic pressure, technicians attach the pier columns to the foundation brackets to permanently support the home.  The hydraulic system is removed, the excavations are back-filled and the foundation, and the home it supports, is left level and stable.

Of course, the excavations required to install the piers can be disruptive, so the homeowner and the foundation repair contractor have the option of installing the piers inside or outside the foundation.

Choosing Between Interior and Exterior Piers

The typical installation for hydraulic push piers is on the outside of the foundation but, with the trend toward outdoor living space in the U.S., many homes have exterior structures that would be costly and inconvenient to repair or replace.  Patios, decks, stamped concrete or paver driveways and elaborate landscaping may all be in the way of installing piers to repair a dropped foundation.

In those cases, piers can be installed in the basement or crawlspace.  Excavations are actually easier because the installer need only to break though a basement floor where minimal digging will provide full access to the footings.  The installation process from that point will be identical to an exterior installation, with repairs required to the floor after the foundation has been raised and the hydraulics removed.

Installing piers in a crawlspace is a little more difficult but a foundation repair contractor that makes use of the latest techniques and equipment can accomplish it.

Homeowners with both a finished basement and significant exterior structures can be advised by the foundation repair contractor as to which installation will work best for them.

Regardless of whether the piers are placed inside or outside the foundation, installing hydraulic push piers will ensure that a damaged foundation is properly and permanently repaired and stabilized.  At U.S. Waterproofing, our foundation repair experts employ their experience along with reliable engineering data and the latest in processes and materials to ensure that our foundation repair work is permanent, cost-effective and as convenient as possible for homeowners.  Why not ask for our free advice if your foundation has dropped or sunk?

Want to know more about repairing damaged foundations with hydraulic push piers?  Please post your questions in the Comments box below.

Tags: interior hydraulic piers, exterior hydraulic piers

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