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Concrete slab that can be lifted

Masters Touch Custom Homes was one of the first Custom Home builders in Austin, Tx to use a state of the art foundation system that was designed for expansive clay soil or unpacked fill. This system was designed by Childress Engineering based out of Richardson Tx. They coined this system Slab Tek. See link

http://www.slabtek.com/SlabTek_Info.pdf

Slab Tek is a scientific system that was built like many suspension bridges across the States. CES developed this system to be used for residential foundation systems in the Richardson, Dallas and Austin Texas Areas.

These areas pose large amounts of expansive clay soils that have destroyed foundations. This system has been designed with budget and safety in mind.

In a nutshell the basic slab design is pretty straight forward. This is a slab on grade pour, with piers drilled into bedrock or friction piers into soil. These piers range in diameter from 10″ to 16″, and depth from 6″ to many feet. The piers are usually spaced 10′ apart.

There are also post tension cables that weave over the piers and throughout the slab. The cables that sit on top of the piers act as a suspension beam from pier to pier. These cable actually allow the engineers to remove any interior grade beams. Grade beams are no longer necessary.

There are also steel buckets that are set into the concrete atop the piers. These buckets are 4″ x 4″ sq. They are set whereas the finish floor of the slab and the top of the buckets are flush. The buckets are left open until the slab has lifted.

I refer to these metal buckets as buckets, in actuality they are lifting devices. The purpose for these devices is to allow a bolt to be turned from the top of the slab. Once each bolt is turned one revolution the slab is lifted off the piers by 1/4″ appox.

Depending on the soil conditions you may need to lift the slab 3″ to 10″. Yes you are actually lifting the slab off the gound. The reason you do this is to keep any expansive soil from applying to much pressure to the slab.

Looking at the slab from the perimeter of the home you will see a void where the exterior grade beam set firmly on the soil. You can now place your hand under your home. Small amounts of back filling are required to cover this crevice.

We used this system on two homes in the Austin Areas. We brought large amounts of unpacked fill into our lots. Rather than compacting all this soil it saved us time and money to have a system like this that required only the piers to be resting on firm soil.

After our cost analysis we concluded that there was a $6700 savings from a standard fill and compaction system.