THE DAY THE HOUSE FELL

This is the title of a book by Dr. Richard Handy wherein he states, "About half the houses built every year in the U.S. are founded on expansive clays, and half of those will eventually show some distress. Of the houses with expansive clay problems, chances are 1 in 5 that the house will become seriously affected." USDA maps show that 60%f of Johnson County soil types are expansive clays, so if I'm doing the math correctly, that means that 1 house in 17 is going to have foundation problems. If this seems high, look in the Yellow Pages and you'll find nearly 80 companies offering foundation repairs. Someone is keeping them in business.

The previous HOMEFRONT presented basement wall repair options and in this issue we present ways to realign a crooked house. If you have sheetrock or plaster cracks, doors that stick, uneven floors, windows that won't open or basement wall splits, these are classic signs of a misaligned house. Misalignment can come from settlement or heave – either way it is typically expansive clay soils rearranging your footings. Listed below are popular systems used to correct settlement:

1. Underpinning – This method uses drilled or hand dug holes positioned beneath the foundation footing. Depth of the hole is subjective, but the goal is to go deep enough to get past expansive clay and into sound soil. The hole is then filled with concrete to produce a pedestal from which hydraulic jacks lift and hold the house. It's an old concept with nearly a hundred years of mixed history.
2. Helical Piers – These are the screw-in devices shown last issue as tension tie backs. They also work in compression and can be screwed into the soil to a predefined torque, then used as jacking platforms as well. They work in light weight structures where push piers won't.
3. Auger piles – Sometimes called mini piles, are made by drilling small diameter holes under footings and filling them with steel and grout. Similar to underpinning they are smaller and thus more are required.
4. Cable Lock – This system works by pushing precast concrete cylinders into the ground to refusal. To make sure cylinders stay in line, a steel cable is strung through them somewhat like a necklace. Once in, they get a top plate jacking platform. There are mixed results with this system.
5. Push Piers - A relatively new system, this uses a hydraulic jack stand and the home's own weight to push steel tubes into the ground. Think bumper jack without a base plate. Instead of the house going up, the jack shaft goes down penetrating the ground. I put 5 push piers under my house in 1990 and they have held well. Push piers' positives are a) tested and certified product capacity, required by certain cities, b) reduced secondary damage to lawns and plantings, and c) fast turn around time.

Each system above has one thing in common. They are only as good as the person who installs them. Do your homework, as there are a lot of pretenders in the foundation repair business. If you need a tie breaker, call one of the several engineering companies that specialize in foundations.

1 "The Day the House Fell", Richard L. Handy Ph.D. © 1995 by ASCE

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