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Q.I'm looking at a wood frame house with a block foundation that is settling. The basement wall sits on a 20-inch-wide concrete footing, but someone later poured a concrete brick shelf from footing to grade and then put brick veneer siding on the house. The soils can't carry the extra weight. What can I do to give the house sufficient support?

A.Foundation repair contractor Dave Cunningham responds: That house needs a deep pier system to support the footings from below. It's a job for a specialty contractor. Your choices on the market are concrete pilings, push piers, or helical piers; which one you choose will depend on what the local contractors in your area have available, and on which contractor you feel most confident about. I'd get at least three proposals before you decide.

Some systems can be installed from inside the basement if there are exterior elements you don't want to disturb. But, generally, you end up excavating around the exterior down to the footing and attaching your piers to the footing from the outside.

Concrete pilings are probably the costliest way to go. That involves auguring a 24-inch hole wherever you need a pier, placing a rebar cage in the hole, and pouring a concrete pier. To raise the house, you have to terminate the pier 2 feet below the footing, with a shoulder that extends under the footing where you can place your hydraulic jacks. If you're just trying to stabilize the foundation but not lift it, you bring the shoulder or shelf right up to the bottom of the existing footing.

Push piers, your second choice, are steel tubes that are pushed down into the soil with a hydraulic rig. The depth is determined by the resistance that builds up as the pier is pushed deeper. The piers attach to the footings with metal brackets. Again, if you're lifting, you'll have to provide for the jacks.

The option I prefer is helical screw piers. These are screwed or augured into the soil rather than driven. If you have bedrock a reasonable distance down, I'd use just one helix per pier and take it down to rock. But if your rock is too deep, you have to rely on the soil to carry the load. In that case, you add more helixes. With two or three helixes per pier, you may have to go down only 8 or 10 feet below the footing, depending on the soil.

The soil is a critical factor -- its bearing capacity will determine pier spacing and depth. It's well worth the money to have a soils engineer evaluate the job, do a soils test, and place the piers for you. Here in Kansas City I pay $225 for that service.

The job itself would cost on the order of $1,000 to $1,200 per pier in my area, and you're likely to need a pier every 4 to 6 feet wherever the footing needs support.