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Answers to Frequenly Asked Questions We have provided a dictionary file to help define some of the technical and construction related terms in our reports in our Dictionary File. These are some of the most commonly ask questions
we receive. Most of our work is performed in the Houston area, and all
of our work is performed in South Texas. Our answers when region specific
are only intended to address these specific areas.
If you don't see the answer to your question here, please don't hesitate to call us. You may also submit your questions via the E-mail. |
Most concrete slab foundations acquire cracks during curing
of the concrete or with heaving of highly expansive clay below the slab
as it acquires moisture after construction is completed. Many of these
types of cracks have little or no effect on the performance of the foundation.
The term "Cracked Slab" is a colloquialism used by real estate agents or
persons familiar with abnormal foundation differential settlement. Cracks
usually develop in the floors and grade beams of buildings having an abnormal
degree of differential settlement. The cracks in concrete are normal and
could be a symptom of differential settlement and not the problem.
It would be advisable to contact a foundation repair company
after the need for repair has been determined by a nonbiased professional
(one who does not sell foundation repairs), who has the training and experience
necessary to determine when the differential settlement has become severe
enough to warrant repair of the foundation. Some homeowners may decide
to have their foundation releveled if the slope of the floors has become
uncomfortable, even though the damage to the structure may be relatively
minor.
Foundation repair companies are not alike. Some management
persons have more experience than others and some have different opinions
as to the type work that is necessary to insure the foundation remains
level. Some foundation repair companies may provide a much better warranty
than others. Different foundation companies may also use different systems
for re-leveling such as drilled, belled bottom footings, pressed pile piers,
and/or watering systems.
It has often been my experience that houses with foundations
properly designed and constructed in accordance with recognized procedures
still develop evidence and/or consequences of differential foundation settlement.
A house constructed on well compacted, non expansive fill, with large grade
beams and subterranean piers have the least likelihood of foundation movement
becoming evident. Even these houses should be constructed with the foundation
not attached to the tops of the piers. The foundation slab should be allowed
to float up and off the piers if the soil expands or contracts. For best
performance of most foundations, it is recommended that the recommendations
provided in our Foundation Care Document be
followed for foundations resting on expansive clay soil.
The cost of maintaining a foundation is usually much less
than the cost of repair. It certainly has less effect on one's normal life
style than that noted while the foundation is being repaired. The cost
of foundation maintenance is usually less than the yearly interest that
would be due on money borrowed to make foundation repairs.
Some locations in the Houston area have soil that is more
expansive than others. The more expansive the soil, the more it changes
volume with change in moisture content, and the greater the effect it can
have on the performance of a buildings foundation. There are some locations
in the Houston area where the soil is a sandy loam which has little change
in volume with change in moisture content.
Subsidence usually refers to sinking of the soil surface
in a large area. Unless there is a fault where the soil shifts vertically,
the subsidence of land usually does not adversely affect the performance
of a building's foundation. In some cases, subsidence of the land results
in tilting of a structure because the surface of the land that has experienced
subsidence slopes toward the lowest point of the subsidence. Uniform tilting
of a structure does not adversely affect its integrity unless the tilt
becomes very pronounced (a slope of greater than .25 inches per foot would
begin to have an adverse effect on the acceptability of a structure for
comfortable habitation).
Fault lines of the type found throughout the Houston area
have a very detrimental effect on the performance of a building's foundation
if the building is located directly across the fault. A building resting
across a fault line cannot be leveled and remain level. A building resting
on a fault must be periodically releveled to maintain its structural integrity.
Although I am not familiar with all areas in the U. S.,
there are undoubtedly areas where the land is not expansive and there is
little or no problem with foundation differential settlement. Local areas,
like most of Galveston Island, are primarily sand which does not expand
and contract with change in moisture content. If the land does not shrink
or expand, a building resting on it is likely to experience little or no
movement.
No one type of a conventional foundation is better or
worse than another if the foundation is properly designed and constructed.
A block, pier, or pier and beam foundation is usually much easier to return
to a level condition if it becomes unlevel. If the foundation is properly
designed and maintained according to local requirements, most any foundation
will perform in a satisfactory manner.
If the foundation of a house has experienced abnormal
differential settlement that is adversely affecting the performance of
the structure, the HUD agency will not guarantee a loan for the property
unless it has been repaired in accordance with a design developed by a
qualified Professional Engineer who will oversee the implementation of
the repair. If there are small cracks in the concrete slab that are not
adversely affecting the building's structural performance and there is
no evidence of abnormal conditions that could result in additional differential
settlement of a particular building's foundation, the HUD agency will guarantee
a loan with an acceptable engineering report. See
description of cracked slabs above.
Hairline cracks in a concrete slab, even those found below
carpeting are not necessarily a measure of foundation performance. If there
are floor cracks and abnormal cracks and separations in the superstructure
of a building, then there is cause for concern that should be further evaluated
by a qualified professional. Cracks typical of those often found when carpeting
is removed can be found in the concrete floor of most garages. See
description of cracked slabs above
The addition of rooms to one or more of the sides of a
house will not have an adverse effect on the performance of either the
addition or the original structure; however, the two separate foundations
will be prone to differential settlement with respect to each other. The
addition of rooms as a second, third, or higher floor of a structure may
adversely affect the performance of the original building's foundation.
If it is desired that an additional floor be added, tests and inspections
should be made to evaluate the foundation, the soil, and the structure
of the original building before continuing with construction.
The best shape for a house resting on highly expansive
clay soil is square, round, or rectangular. U, C, H, L, and other irregular
shapes usually exhibit evidence of foundation movement more readily than
other types of construction. The expansion and contraction of expansive
soil at the inside of the U, C, H, or L shaped houses tend to force the
protruding wings apart, causing damage to the superstructure and the foundation.
The resale value of a house having need for foundation
repair can be increased significantly by having the foundation releveled.
The value of a house which has had the foundation repaired as compared
to a similar house which has not had the foundation repaired and does not
need repair is about the same. It is pointed out that some people will
not purchase a house that has been releveled.
Yes, an unqualified foundation repair contractor can cause
additional damage to the structure and foundation while releveling the
foundation.
For best performance, a repaired foundation should be
maintained in much the same way as the foundation of a house resting on
expansive clay soil which has not been repaired. See our
Foundation Care Document
Properly installed piers should last for the life of the
building. The piers should ensure less movement than the building would
have experienced if the piers were not installed. For
best performance, a repaired foundation should be maintained in much the
same way as the foundation of a house resting on expansive clay soil which
has not been repaired. See our Foundation
Care Document
A foundation watering program and/or system can, in many
instances, be implemented rather than installing piers to relevel a foundation.
If the house has been out of level for an extended period of time (several
years), it is probable that watering will not cause the foundation to become
more level. If the differential settlement has been caused by washing away
of soil or by movement of a fault, then watering of the soil will have
little or no effect. The results of a watering program is usually much
slower than installation of piers.
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