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Buyers Beware – Part 2

I once inspected a slab foundation of a residence for a lady who had owned a home for 15 years and was in the process of selling it. The home was about 2 years old when she purchased it from the original owner. It is located in a suburb of Dallas well known for having highly expansive clay soils. (This means that when the clays experience an increase in moisture content, they can expand significantly.)

She told me that she had a contract on the house but the buyer backed out after his general inspection reported that foundation movement had occurred. She did not understand why the inspector would come to that conclusion since, in 15 years, she had not had any sheetrock cracks, brick cracks (except for one minor crack) nor experienced any problem with any of the doors.

My investigation showed that the foundation was over 6” out of level and I concluded that the back of the foundation had heaved upward because of soil expansion. Furthermore, all of this occurred prior to her buying the home.

I suspect that the original owner knew about the problem and made cosmetic repairs and dumped the property. Unfortunately, when she bought the home (15 year ago), her general inspector did not warn her about the condition of the foundation.

The good news was that there had not been any significant foundation movement since she purchased the house; the bad news was that prior to her purchasing the home, it had heaved upwards and was 6” out of level.

If a problem with a foundation is defined as it being significantly out of level because of upheaval, then the logical remedy would be to lower the heaved portion. This can be done, but it is outrageously expensive and is therefore done infrequently. Because of the expense, this was not an option for her.

However, if a foundation problem is defined as having recent foundation instability, then she was in good shape because the home had not moved noticeably for 15 years. However, the big problem was that the foundation was over 6” out of level.

There was no financially reasonable remedy for solving her foundation problem. So, because the seller had covered up defects and she was not properly advised when she purchased the home, she was stuck with a nice home in a nice neighborhood that she could not sell at the going market value.

In a defense of her general inspector, the original seller of this home had the cosmetic damages repaired prior to putting the home on the market. If a seller of a home hires a professional painter and brick mason, they can make most defects in the sheetrock and brick disappear. And if a general inspector does not see cosmetic defects normally associated with foundation movement, they (at least some of them) assume that the foundation is ok.

So, could this have been prevented? Yes. The key is to either hire a very detailed general inspector who can look beyond the obvious (and possibly a structural engineer that will take slab elevations).

When she purchased the home, her general inspector (and her realtor) should have noticed the slab diselevation (I do not know how they missed noticing that the master bath was over 2” out of level). Nor did they notice that the kitchen base cabinets, the hall bathtub, the fireplace hearth and the fireplace mantle were all noticeably out of level.

To repeat, a buyer’s first line of defense against buying a house with a damaged foundation is to hire a competent, detailed-oriented general inspector. If there are indications of unusual foundation movement, he may recommend hiring an engineer to do a more detailed inspection of the foundation.

 
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Posted by on October 1, 2014 in foundation repair

 

Buyers Beware

Recently, I have seen a few sellers of a home either not disclosing existing foundation problems or purposely hiding critical information about it. One example follows:

The seller (a house investor aka “flipper”) provided documents to the buyer that showed that 35 piers had been installed under the front portion of the foundation, including in the interior. The documents also showed that the foundation had been 8 inches out of level (prior to the foundation repairs). The home had been extensively remodeled after the pier installation.
The prospective buyer retained me to inspect the foundation. I determined that the house was still over 3 inches out of level and that the front portion of the foundation had been lifted about 5”. I recommended that the buyer ask if the seller had had the sub slab plumbing tested after the lift. The seller said that the foundation repair company told him that it was not necessary so no test had been conducted.
I advised my client to insist that the plumbing be checked. A few days later, the seller sent a copy of an invoice from a plumber that stated there were no plumbing leaks. However, the address on the invoice did not exist, the plumbing company did not exist and the plumber who reportedly did the test was not a licensed plumber. The invoice was obviously a fake.
The buyer backed out of the contract

 
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Posted by on September 15, 2014 in foundation repair

 

Miscellaneous Surface Drainage Comments

Too many times, I see inadequate surface drainage conditions around a foundation that can potentially cause foundation movement. Because of the presence of expansive clay soils, poor drainage conditions around a foundation in North Texas can increase the likelihood of soil expansion (with the resultant upheaval of a slab foundation). The expansion of clay soils is caused by an increase in the soil moisture content.

Some clays in North Texas are highly expansive while others not so much. In areas that have highly expansive clays, soil expansion can cause a slab to heave upwards several inches (I have seen 12” of upheaval in Irving, Texas). However, in other areas, having water ponding near the foundation does not cause a noticeable foundation problem but the water is more of a nuisance. It is a good practice to always maintain excellent drainage conditions around a foundation, regardless of what the problem is.

Some builders make it nearly impossible to have good drainage conditions because they did not install the slab foundation high enough around the ground surface. This seems to be especially the case in many rural areas.  

Rural Residential Developments

I got a call from a homeowner in a rather rural community (a few dozen homes in a non-incorporated area) that said he had a drainage problem and asked me to inspect it and design a repair. Once at his house, I noticed that not only was the ground surface around his home flat but so was the entire neighborhood, so there was no place for the water in his yard to drain. He then showed me photos of his neighborhood after a heavy rain and there was a foot or so of water in the streets (the streets were somewhat lower than the front yards) but the water came up very close to his house (and his neighbors). I told him (the obvious) that improving the drainage conditions around his home was meaningless until the neighborhood drainage was repaired.

The homeowner ended up suing the builder and the developer (who installed the streets, water, lots, etc.). Both the builder and developer took bankruptcy and the homeowner took a real bath on the house value.

 Flower Beds

The foundation should be installed high enough so that when (if) a flower bed is installed adjacent to the house, the ground surface can still slope enough so water can run rapidly away from the foundation. (Refer to the Drainage Guidelines below).

Swimming Pool Drainage

If I were to build a swimming pool, I would specify that any drainage catch basins or drainage channels had to be a minimum of 9” diameter for the catch basins and 4” wide for the drainage channels. Not the absurdly small drainage systems normally used that get clogged up easily.

 French Drains

Over the years, I have seen several french drains situated immediately adjacent to the foundation. Depending on the drainage system construction and soil characteristics, it is possible that the soil moisture content can be increased because too many times, water pools around the drainage pipe. This can be like a sub slab plumbing leak and under the “right” soil conditions can actually cause a slab to heave up. To prove this would require some geotechnical testing. But to be safe, the drain system should be installed a few feet away from the foundation.

Engineering Drainage Guidelines

The “Guidelines for the Evaluation and Repair of Residential Foundations” adopted by the Texas Section of the American Society of Civil Engineers (ASCE) in 2002 with an effective date of January 2003, states the following concerning the drainage conditions around a foundation: “Where practicable, for adjacent ground exposed or vegetative areas, a minimum slope of 5% (i.e. 6 inch drop over a 10 feet distance) away from the foundation should be provided for the first 5 feet all around (the foundation). (Drainage) swales should have longitudinal slopes of at least 2% (i.e. 6 inches over a 25 foot distance), if practicable, and 1% (3 inches over 25 feet) at a minimum.”

 The ASCE also developed a guideline for the “Recommended Practice for the Design of Residential Foundations”. In that document, they state the following concerning drainage: “For adjacent ground exposed or vegetative areas, provide adequate drainage away from the foundation (minimum five percent slope in the first ten feet and minimum two percent slope elsewhere). The bottom of any drainage swale should not be located within four feet of the foundation. Pervious planting beds should slope away from the foundation at least two inches per foot. Planting bed edging shall allow water to drain out of the beds.”

 

 

 
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Posted by on January 1, 2013 in foundation repair

 

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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Are Engineers Created Equal? Part II

Last week, the blog discussed an example of poor engineering judgment. Another example of bad engineering advise was at a home built on the side of a steep hill which ran down to a creek. It was estimated that the builder brought in over 15 foot of fill material to level the lot prior to installing the foundation. As is usually the case, the fill material was not properly compacted so, over time, the fill material consolidated causing the slab foundation to settle several inches. (Even if the dirt the builder imported – the fill material – had been properly compacted, the foundation would have still settled because gravity, over time, would have pushed the dirt downhill. Only a solid retaining wall would correct this problem.)

Within a few years of moving into his brand new home, the homeowner started noticing indications of severe  foundation settling. This resulted in numerous slab cracks, out of level floors, sheetrock cracks, brick mortar cracks and out of level doors.

He retained an engineer to design a repair for the foundation. The engineer specified the installation of about 50 drilled concrete piers that only went to the 12 foot depth. In other words, the piers on half of the home were installed completely within the fill material. Needless to say, 1/2 of the foundation continued to be unstable for several years, requiring continual “adjustment” of the piers. The only remedy for this foundation is to replace the existing piers with piers that are founded in a stable bearing stratum. However, because of the expense, the homeowner has not been able to do so.

It should be said that a post construction pier will typically only prevent vertical movement (downward or settlement movement) and not horizontal movement. Some extreme topographies require a stable retaining wall to stop horizontal movement of the soil.

So, a foundation situated on the side of an extreme slope needs special attention from an experienced engineer who understands the forces of gravity.

Both of these homeowners had retained structural engineers but unfortunately, the engineers did not understand the basics of soil behavior.

Jim McNeme, P.E.

Structural Engineer

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

 
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Posted by on April 10, 2011 in foundation repair

 

Are All Engineers Equal?

Part I

There are two disciplines of engineers that usually investigate foundation movement. The most prevalent is a Structural Engineer (who specializes in structural analysis) and the other is a Geotechnical Engineer (who specializes in the soil analysis). Both have been certified by the State of Texas as being qualified to perform engineering analysis within their area of expertise (licensed professional engineer).

Over the years, I have come across several foundations where the homeowners had retained a Structural Engineer to design a repair for their unstable foundation, however, the repair/remedy was not successful because of poor engineering judgment. This blog series will discuss a couple of good examples of bad examples.

There is a neighborhood in North Dallas that is well known for its highly expansive clay soils and its poor quality foundations. Most of the foundations of the homes in this neighborhood have had foundation repairs. Several years ago, a homeowner asked me to investigate his continuing foundation movement. Several years prior to calling me, he had the foundation repaired by a well known foundation repair company in Dallas. The engineer for that company recommended 40 or so drilled concrete piers. The piers installed were double shaft concrete piers (8” diameter) that were to extend “to a depth of 9 feet or to rock whichever came first”. Well, rock in that neighborhood was over 40 feet down, i.e., the piers did not extend to a stable stratum and the piers were so unstable so the home was continuing to experience significant differential foundation movement to the point that doors were jammed shut, sheetrock was always cracking, etc. The severity of the problem varied with the seasons (wet springs and dry summers).

In North Texas, the soils tend to dry out every summer. It is generally accepted that they dry to depths of 12 to 15 feet. They may not get bone dry, but they get drier than during the rainy seasons. As expansive clays dry out, they shrink and anything within that zone of moisture change will move. This includes piers. Every summer, some of the piers would settle an inch or so but every winter/spring, they would rebound back upward. He said the foundation used to recover better but lately, the settlement is getting worse and staying bad. The only remedy was to install new piers of a known quality and disconnect the old piers from the foundation. This cost him about $35k. The new piers I specified were steel pipe piers that went to depths of about 40 feet. The foundation has been performing properly since.

Jim McNeme, P.E.

Structural Engineer

http://www.GeoDFW.com

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

 
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Posted by on April 2, 2011 in foundation repair

 

Foundation Movement IV

Upheaval – revisited again

I recently inspected a slab foundation of a 10 year old house in an unincorporated area in North Texas (no local building codes). The residence had been experiencing foundation movement to the point that the front door was jammed shut, numerous large sheetrock cracks existed throughout the house and much of the foundation was obviously out of level. The homeowner said that sometimes the front door would work properly (during the dry summer months) but other times, it could not be used (typically during the winter/spring or after a few days of rain).

The homeowner also said that when the home was being built, the builder installed numerous concrete piers around the outer perimeter of the foundation and that they were 6 to 8 feet deep, however, no piers were installed under the middle of the slab. I asked the owner if the builder had obtained a site-specific soil report for the foundation design engineer to use. He said no, that the builder had over 20 years experience in construction and said he did not need an engineer or soil report.

I determined that the piers installed by the builder were so shallow that the expansion of the clay soil (during the wet weather) caused the clay to grab the sides of the piers and push the piers up. During the dry weather, the soils would shrink and allow some subsidence of the piers. Unfortunately, the upheaval each year was much more severe than the settlement so that, each year, the outer edge of the foundation moved a little higher than the previous year. When I inspected the foundation the outer perimeter of the slab was over 4” higher than the middle.

There were two possible remedies to this, neither of them delightful. One remedy would be to install piers both around the outer perimeter of the foundation AND throughout the interior. The interior piers would then be used to raise up the interior to match (as close as possible) the slab elevations around the outer perimeter of the house. Then the unstable builder installed piers would be cut loose from the foundation and a void would be left under the slab to allow some movement of the soils. This technique, though used somewhat commonly (usually when the builder is threatened with a lawsuit) has some limitations to its success and requires the homeowner to move out of the home for a few weeks and it also devastates the below slab plumbing (and other things).

The other possible remedy may have been less invasive and less costly but it involved a two step phased approach to the repair. IF a void remained under the outer portions of the slab (because the piers pushed the foundation up), it may have been possible to expose all the piers and cut them free of the foundation and attempt to lower the slab back down to its original position. This is a rather risky technique because sometimes the soil under the slab expands up and leaves no void space between the slab and the dirt, so the slab could not be lowered. So before this technique is attempted, further investigation would be required. Another potential problem with this approach was that when the soil moved again, so would the foundation.

In the end, the homeowner decided that he was ok with the foundation as it was and was not interested in spending any further money on it.

It would not have taken much very much additional money for the builder to install the piers properly (to a stable bearing stratum) but apparently the builder did not understand all that was involved in building a slab-on-pier foundation in expansive clay soils (even though he claimed that he had been building homes for over 20 years and never had a problem with one of his foundations).

The primary lesson to be learned here is when constructing a foundation on problem soils, the piers must be designed by an experienced structural engineer and installed by a knowledgeable builder. Also, piers must be installed into a stable bearing stratum (among other things). This requires conducting soil borings, testing and an analysis by a geotechnical engineer.

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

Jim McNeme, P.E.
GeoDynamics

 
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Posted by on February 26, 2011 in foundation repair

 
 
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