Bowing Walls - The Tieback Solution
By: Dave Cumings
To solve the problem of tipping concrete walls, several issues must be addressed. First, it's important to find out why it's tipping. Is it hydrostatic pressure building up behind the wall? Water freezing and heaving is the most common cause. Or are tree roots pushing the wall inward? Perhaps there was improper back fill at the time of construction.
Secondly, the condition of the wall should be assessed. Is it badly cracked? What's the construction of the wall? Is it made up of poured concrete, masonry block, or something else?
Third, potential complications should be addressed. Is this a finished wall that will require expensive aesthetic work after the wall is repaired? Is the wall very close to a property line? Is the structure located downhill from neighbor's property?
Once these issues have been addressed, a repair option should be chosen. Repair options include jacking up the house, removing and replacing the wall, or securing the wall with helical tieback anchors.
Removal and replacement is obviously very effective and gives you a new wall. It's also very disruptive and gives you a messy and very expensive process.
If the problem is tree roots, you can cut the tree down. But that decision is not always that easy. Many factors apply. The owner must decide the value of the tree. If necessary, an arborist can assist regarding root control.
On the other hand (and in most cases) helical piers are an excellent solution. These helical tieback anchors are inserted through the wall and turned into the soil at an angle from horizontal of 20-25 degrees. When the soil stiffens and the installation pressures attain required levels, the inside end of the helical pile is transitioned to a threaded rod. Using a steel plate or waler, support pressure is created by a nut and washer.
This stabilizes the wall. But if you want the wall pulled outward and not just stabilized, the soil against the wall must be removed to allow room for the wall to move outward. The principle limitations include rubble walls, which are not candidates for helical piers, and walls cracked so badly that walers won't adequately support it.
It is highly recommended that landscape grades create a positive flow away from the structure. Also, gutters should be installed and/or maintained to function properly to direct water away from the building. Ground tiling to direct surface water away can be very helpful.
Helical piers (tiebacks) are an excellent, unintrusive, cost-effective way to stabilize tipping basement or retaining walls. Most repairs are 1-2 day duration. The house needs to be a minimum of 12-15 feet away from the property line for this process to be effective. Interior finished walls will also need to be replaced. After repair with helical tieback piers, the wall is ready for immediate service without set up or cure time. Consider tiebacks for your tipping wall needs!