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Guidelines on Choosing a Foundation Repair Company

There are several hundred foundation repair companies in North Texas. How does a homeowner determine which one to use? Frankly it is difficult unless he or she has guidance from a friend or an independent engineer.

If friends have had foundation repairs done to their home, a key question to ask are how long has the work been completed and have there been any further problems? If the work has been completed 5 years or more without any further difficulty, then it is obviously an indication that the repairs have been successful, to date. (It should be said that because a pier will only have an impact on the foundation within a 7 or 8 foot radius, that a foundation may experience settlement in an unpiered area.)

Since I am an independent engineer (not affiliated with any foundation repair company), I recommend that hiring an engineer is the way to go. Many times, that engineer can recommend a list of reputable foundation repair contractors to the homeowner. (The engineer does not (or at least should not) have any financial ties to those companies.)

Once a foundation repair contractor is interviewed, several questions/points need to be brought up:
• Has he ever worked in your neighborhood? If so, where and what are their phone numbers?
• Does he have insurance?
• What is his warranty program like? What is covered and what is not covered? Have they ever had to return to service their products under their warranty? If so, what happened? Why did their piers fail? How did they fix it? Can you contact the homeowner?
• Will he obtain a building permit from the city? Does the city require an engineering report to get the permit? Does the city require a letter from the engineer to close the permit? Will his engineer visit the site during the repairs and conduct a spot inspection of the work while it is being done or will he show up after all the work is completed?
• How long will the work take?
• Does he use his own employees or does he subcontract the field work to others? Does he use day laborers?
• Will he cover all excavations with plywood after he leaves the site for the night (to keep people from falling in the holes)?
• Will the various defects (doors out of level, sheetrock/brick cracks) improve during the lifting process?
• Will his proposal include taking slab elevations? Will he give you a copy?
• How much of an improvement in the slab elevations does he expect to make? (He will probably not be able to give you a precise answer to this question but it will raise his awareness that you are interested in the final results.)
• If he has to jackhammer through any concrete to install the piers, will he make the concrete edges square before replacing the concrete (and not leave the edges jagged)?
• After the work is complete, will he provide a letter of compliance from an engineer stating that the work was done properly? This is especially important if the home is put up for sale within a few years.
• Will he obtain a plumbing leak test upon completion of the work?
• Will the foundation repair company repair all the existing brick / brick mortar cracks?
• When is final payment required?

Jim McNeme, P.E.
GeoDynamics
www.GeoDFW.com

For more information on foundation movement, go to http://www.GeoDFW.com

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Posted by on April 22, 2011 in foundation repair

 

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Foundation Movement – Part III

Foundation Upheaval

In previous blogs, we discussed that foundation movement can be categorized into two types: foundation settlement (the most common) and foundation upheaval (the most difficult to remedy by foundation repairs). Today, I will discuss the latter: upheaval.

As a Structural Engineer, I recently represented a homeowner of a new custom home (costing about $1mm) where the foundation heaved upwards over 5” – within the first year! The slab was constructed over drilled concrete piers; which is the type of foundation I would design for myself if I ever built a new home (shoot me dead first).

The homeowner called me to check out his foundation after the builder (and his engineer) had inspected the home and told the homeowner that “it was just normal settlement” (however, it did not settle, it heaved upward). As part of my inspection, I reviewed the foundation design and determined it to be a good design. So, if it was a good design, why did the foundation move and cause numerous sheetrock cracks, slab cracks, etc.?

The answer to this very good question is that it moved primarily for 4 reasons:

  • The foundation was constructed on a lot with highly plastic clay soils (soils that expand and lot when the soil moisture content increases and shrinks a lot when the soils dry).
  • The builder did not follow the engineer’s specifications for site preparation.
  • The builder did not provide adequate drainage conditions around the foundation.
  • The builder built the foundation in 2006, during a record breaking drought in North Texas.

I will focus my brief discussion on the last reason, which I consider being the primary problem.

This particular residence is built in a suburb of Dallas that is well known for its highly expansive clay soils. Prior to designing the foundation, the builder obtained a geotechnical report that indicated that the soils at the site were such that 6 inches of PVR were possible. PVR is “Potential for Vertical Rise”; this means that under the “right” conditions, the soils could expand upward over 6 inches. The geotechnical engineer recommended several measures the builder should take to minimize any foundation movement. However, the builder did not follow the recommendations and the foundation heaved upwards about 5” in the first year.

In 2006, when the slab was built, the highly plastic clay soils, because of a record breaking drought, were in an extremely “shrunken” state. Unfortunately, when the drought ended and the rains returned, the soils expanded significantly and lifted the slab up off the piers. Because of the large size and shape of the house, a satisfactory remedy was not economically feasible.

It should be said that even if the drainage conditions around the foundation had of been perfect (and they were not), the slab would have still been lifted up off the piers by the expanding clay. When the rains returned, the soils were going to be re-hydrated no matter what the drainage conditions.

As a side note, the builder also built the slab too close to the ground surface, plus it was a flat lot so the surface water had no place to run. I guess the builder was not aware that water runs down hill.

Fortunately, the homeowner retained an experienced attorney who was able to get the builder to buy the house back. The builder told me that he now pre-swells the soils prior to installing a foundation (which was one of the recommendations his geotechnical engineer had made originally). After the builder bought the house back, he fixed the cosmetic defects in the house and then resold it in an “as is” condition at a discounted price.

For more information on foundation movement and foundation repairs, go to www.GeoDFW.com

 
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Posted by on February 5, 2011 in foundation repair

 

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Slab Cracks

Slab cracks in slab foundations can cause great anxiety to homeowners. However, many slab cracks do not pose a structural problem to the foundation. For example, many times, slab cracks appear soon after the concrete is installed and are usually caused by poor quality control by the concrete contractor. Most of the time, these types of cracks are hairline in width and are only superficial (do not penetrate deep into the slab) – however, there are exceptions. Generally speaking, these types of cracks are related to the excessive loss of moisture in the concrete and are called plastic shrinkage cracking. Plastic cracking is related to many factors during the slab installation process, including: wind, low humidity, excessive water content in the concrete mix, exposure to the sun, etc. These types of cracks will not usually have a negative impact on the structural ability of the slab.

The cracks that concern us the most are the cracks caused by foundation movement. Most of these types of cracks are hairline to 1/16” wide or so, however, I have seen slab cracks that are ¼” and wider. Many times, an extensive network of slab cracks is an indication of poor rebar placement and/or significant foundation movement.

Unless a slab crack is covered with floor tile (which will also crack) or the slab crack allows excessive moisture penetration from the subgrade soils, most slab cracks cannot be easily detected under carpet or wood flooring.

The usual remedy for a slab crack caused by foundation movement is twofold:

  1. Stabilize the slab so it cannot move. This is typically done by installing piers.
  2. Epoxy inject cracks that are 1/32” wide or wider.  This type of work needs to be done by an experienced technician.

There are other reasons concrete slabs crack but that is another topic for another day.

Jim McNeme, P.E.

Foundation Engineer

www.GeoDFW.com

 
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Posted by on January 2, 2011 in foundation repair

 

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