Sunday, August 7, 2011

Foundation Repair Systems, which one is the best?

In the world of foundation repair, the most common question that I hear is "Which system is the best system?"  There are many systems, and I can imagine that to a homeowner all the information given to them about why one company's system is better than the other can be quite confusing.  Here is a quick breakdown of the different structural repair systems......

Drilled Piers/Screw Piles:  
    1) Straight Shaft Drilled Piers - Piers that drilled and cast in place.  The are installed by excavating a hole in the soil, placing steel reinforcement within the shaft, and finally adding and vibrating structural concrete or redimix.  These piers should be drilled to stable soil or load baring strata (where possible). The concept behind this type of pier is to achieve depth below the active zone of the soil, and allow skin friction to hold the pier in place.

    2) Bell Bottomed Piers - Same concept as the straight shaft pier, except with an under ream underneath most commonly 3 times the diameter of the pier shaft.  For example, a 6" pier shaft should have a 18" bell


   3) Helical Piers/Screwpiles- Steel Pipe or Square Stock that are mounted to a helix plates spaced at intervals, then  screwed into the ground.  Anchor brackets transfer the load of the house to the pier.



Pressed Pilings
     1) Concrete Pressed Pilings - Prefabricated Concrete Cylinders (usually either 6" or 8" in diameter, and 12" in legth) are pressed into the grade using the weight of the structure above them.  A hydraulic press is normally used as the driving force to shove them in the ground, one at a time until they simply can no longer be pressed.  Once this point of "refusal is reached" the structure can then be lifted.  These are also commonly caused "friction pilings", but the friction comes in many forms.  Skin friction on the sides of the piers, and friction from the pier to pier contact are just a few. 

    2) Steel Pressed Pilings - Installed just as a concrete pressed pilings, but using steel pipe in it's place.  Steel pipes are most commonly 3", or 2 7/8" in diameter.  These piers should be double walled.  Meaning that there are two pipe sets, one inner that is smaller in diameter than the outer set.  The reason for this is because the pipes are hollow, and extremely narrow in diameter. There is not enough surface area for the next pile to rest on.  The pipe sets should be offset as well so they can be stacked as the are pressed. Companies use precut steel, or sometimes 10 foot shafts driven next to the foundation and bracketed or bolted onto it.

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There are also however, what are called "Non Structural Repairs".  A non structural usually involves repairing the conditions that are causing the foundation movement, instead of transferring the load of the foundation onto piering system.

These most typically are drainage improvements and soil injections.  Since soils are very similar in nature to sponges, non structural repairs involve either de-hydrating the soil (via catch basins, drain pipes, guttering systems, french drains, and chemical injections) or re-hydrating the soils via underground watering systems.  Honestly, while these methods CAN be highly effective (and I've seen them work extremely well) their effectiveness is not guaranteed.  Also, most of the time the effects on these repairs are not seen for quite some time.  They are usually less expensive than a structural repair, but do require further evaluation and patience.

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Now, one of the tricks in the foundation repair industry is the battle of "Our system is better than their system".  To be honest, they are all good systems. They all work, and most companies back these with lifetime warranties.  The question is though, which one is most appropriate for your home?

For example, if you have one of the older wood framed houses here in Houston, due to concrete deterioration over time, and the fact that your house is very light weight, a pressed piling system (although highly effective) might not be the best option for your home.  The reason is depth is sufficient depth is hard to achieve. Because of the stiffness of sub-grade soil and the force it takes to drive those piers, the cosmetic distress and risk of associated distress on both the foundation and the plumbing associated with a pressed piling system might not make it ideal for that house.  If you have a three story house with brick veneer a steel piling system (due to the fact that a steel pier can hold more weight) might actually be a more affordable system.  Also local geology comes into factor.  The soils in Livingston, or Huntsville, or Conroe are much different than the soils in Sugarland, or Fulshear, or Baytown.  Pressing a concrete pier in Conroe is very difficult, and a steel pier or drilled pier might be better suited for your house because it is better fit for that soil.

The last thing is that if your house has heaved due to soil conditions, a partial repair is absolutely not ideal.  The key to all of this is that the repair (both in design and materials) has to make sense for your house.  Look at the logistics of it, and in the end if the repair or company is one that you do not feel comfortable with, if the company has not fully explained to you the "why" and the "where" of the repair process, call an engineer and get an open opinion. It's better to have one problem corrected, than to have an entirely new set of issues to deal with.

If you have any questions over which system might fit best for your home, give us a call:


You can call us here: 888.434.8232  
You can email us here evals@permapier.com
or you can click here to sign up for a free evaluation.
Or you can email me directly with any questions at: brian.gilchriest@permapier.com