How to Inspect, Diagnose, & Repair Concrete Foundation Cracks, Movement, Settlement, Leaks InspectAPedia® -
Poured Concrete Foundation Defects listed, described & explained
How to identify and evaluate cold pour joints, shrinkage cracks, holes, settlement cracks in foundations
How to identify and diagnose Poured Concrete Foundation Wall & Slab Cracks, Movement, Settlement, Foundation Leaks, & Leans, Bulges, & Other Foundation Defects
Photographs of foundation damage patterns and types
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Here we discuss How to identify and diagnose Poured Concrete Foundation Wall & Slab Cracks, Movement, Settlement, Leaks, & Other Defects
involving reinforced concrete foundations and concrete walls, such as damage due to shrinkage, impact, settlement, frost or water damage, and other causes.
Also see this close companion article: SLAB CRACK EVALUATION which discusses in detail the process of evaluating cracks, settlement, leaks, shrinkage, or other damage
in poured concrete slabs, monolithic slab foundations, and concrete floors, and see FOUNDATION CRACK EVALUATION which
discusses evaluating foundation damage by examining concrete crack size, shape, pattern, and location.
Examples of structural & other failures in Poured Concrete Foundations: Cracks, Leaks, Movement, & Other Defects
How to Identify Cold Pour Joints in Concrete Foundation Walls
Cold Pour Joints in concrete foundations which leave visible lines in the concrete foundation wall are not usually a structural problem but may in some cases form a dry joint which permits water leakage through the foundation wall.
Cold pour joints occur because of the time delay between subsequent "pours" into the foundation forms.
An astute inspector, by
noting the position, pattern, and slope of the cold pour joint, can probably determine the position from which the concrete
was poured into the forms (the high end of the sloping lines) and the extent of delay between pours (evidence of water leaks
through the joints indicates that enough time passed for the lower pour to solidify).
Our photo (left) provides a closeup of a distinct cold pour joint in a concrete foundation wall of a 1980's home in New York.
Reader Wade Mariage has pointed out that cold pour joints may also occur due to the accumulation of form-release oil on top of a pour into oiled aluminum concrete forms. As Mr. Wade noted and we agree, even when the concrete crew "chuck" the "mud" (concrete) between pours to improve bonding of the subsequent pour and to reduce pour marks, these marks still often appear in the cured concrete. If the aluminum concrete forms are heavily oiled the cold pour mark may be still more visible.
Mariage asserts and we agree that normally a cold pour line is not a structural concern. Exceptions are wall leaks or failure of subsequent pours to bond well if the concrete actually sets between pours - unusual events in normal concrete construction.
Visual clues of cold pour joints give a history of construction sequence and timing: In the photograph above one can just
make out the lines of boards used to construct the forms used to pour this foundation wall. The visual clues combine
to suggest how this foundation wall was constructed and what happened later. The use of boards and somewhat rough
workmanship suggest a "do it yourself" project, perhaps by a small builder or the homeowners themselves. Small contractors
or homeowners might rent a cement mixer and mix small batches of concrete, perhaps not even a cubic yard at a time.
Because a fair amount of manual labor would be involved in mixing each small batch of concrete, it's possible that so much
time elapsed between concrete pours that the lower pours had cured and hardened so much that subsequent concrete pours
did not bond with their predecessors. This (speculative) history might explain why we see horizontal cracks in this
concrete wall in a pattern which tracks, almost exactly, the cold pour joint lines in the wall. If the builder also
skimped on reinforcing steel or wire in the wall that might be another factor in the development of these cracks in
response to earth or frost pressure from outside after the wall was cured.
Where was the concrete truck, how full was it during pouring of the foundation?
The cold pour joints in this concrete foundation wall show us that the concrete truck made the first pour from the corner of this foundation wall. Concrete spread roughly evenly away (and sloping down) from each side of the foundation corner as the concrete was poured into the forms. The truck was probably nearly empty when it started this pour as we don't see much height of concrete below the cold pour joint.
A full concrete truck probably made the second pour as we see no other cold pour joints up to the top of the foundation wall.
This interesting cold pour joint tells us that this wall was poured from its two opposite corners, leaving a vee-shaped cold pour joint in the center of the wall.
Although we can see the dark line between the two concrete pours that formed this wall section, as there was no evidence of an actual crack and no water leakage in the wall, this cold pour joint, like the one above, is not a structural concern - it's cosmetic. Sometimes we can learn something subtle about how a home was constructed and how organized was the builder or mason contractor by observing these clues.
How to Identify Concrete Shrinkage Cracks in Concrete Foundation Walls
Concrete shrinkage cracks are not usually a structural problem but may permit water leaks through
the foundation wall. Shrinkage cracks are often mistaken by owners and inspectors who, failing to observe
the characteristic discontinuous path of the crack and its meandering path, mistake shrinkage cracks for structural damage.
How to Identify Recognize and Repair Holes and Penetrations in Concrete Foundation Walls
Holes and penetrations in concrete foundations such as poorly-sealed openings left for piping for water or electrical lines
or where form ties were broken off may form points of water entry into the structure but are not normally
a structural concern.
The "patched" holes shown in this photograph had been a source of chronic leakage and basement
water entry since this home had been constructed about two years before this photograph was taken. While several
unsuccessful attempts had been made to seal and patch this leak point in the concrete foundation wall, none of the
repairs had tried using a suitable product sold for that purpose and the wall was still leaking.
Of course the
root problem was that surface water was not being directed away from the building outside. These holes were high
enough on the foundation wall that it would be reasonable (and perhaps preferable) to seal the wall from outside
before also re-grading to drain surface water away from the building.
How to Identify Settlement Cracks in Concrete Foundation Walls
Concrete foundation settlement cracking such as from footing settlement, absence of or poorly prepared footings,
water leading to settlement or actual loss of soils, thus undermining the footings (this can occur and can damage most foundation
types), or movement of the foundation due to nearby blasting or excavation work.
Shrinkage cracks in concrete occur only during curing and will appear mostly in the first 28 days after a wall or
floor is poured. If cracks noted and documented after this time continue to increase in length or width, some other
cause is at work and further investigation is needed.
The concrete settlement crack shown here appeared initially
in this wall as a hairline fracture of less than 1/16" in width. The homeowner monitored the crack and watched
it increase in width to nearly 1/2" over the following 12 months, leading to the correct inference that there was
structural movement going on.
In this case we traced the movement to uneven footing settlement which was aggravated
by the combination of having placed the footing partly on bedrock, water from roof and surface
spillage and runoff causing soil settlement (the contractor had not compacted the backfill under
the footings), and by ongoing foundation blasting at a neighboring lot.
Concrete foundation damage from horizontal loading, vehicles, frost is less commonly seen than with unit-construction
materials such as brick or masonry block but might occur under unusual conditions.
Concrete foundation damage from unusual point loads
How to Identify Form Tie Marks and Leak Points in Concrete Foundation Walls
Concrete Foundation Form Tie leaks: Leaks at the location of concrete form ties used during construction of a poured concrete foundation are not normally a
structural problem but they can be blamed for basement water entry.
Form tie leaks occur in a poured concrete foundation wall
where the form ties used to construct the foundation have left penetrations in the concrete walls.
Form ties are wire or steel
connections between the two vertical sides of the wood or steel concrete form. Concrete form ties are needed to prevent
the forms from separating and bulging from the weight of the concrete poured into the form. The best
solution to concrete wall form tie leaks is to keep water away from the foundation from outside.
Other Types of Foundation Damage to Concrete Walls or Floors
Leaning concrete foundation walls or structural walls due to: water, frost, or earth loading, vehicle passage too close to the wall, inadequate footings, soil undermining
Concrete foundation wall cracks*: settlement, shrinkage, cold joints
Concrete foundation spalling due to poor concrete mix, too much water, excessive working of the surface, pouring during cold weather without
proper additives, roof runoff rain-splash erosion of the wall surface.
Articles on Repair of Foundations
For detailed information about foundation repair methods, including repairs to various kinds of cracks in concrete, see:
FOUNDATION REPAIR METHODS for our catalog of Foundation Repair Methods - Examples of Typical Foundation Repairs for various types of foundation cracks, leaks, settlement, movement, or other failures
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Additional technical contributors & reference sources for this article are listed below.
Use links just below or at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.
"Concrete Slab Finishes and the Use of the F-number System", Matthew Stuart, P.E., S.E., F.ASCE, online course at www.pdhonline.org/courses/s130/s130.htm
Sal Alfano - Editor, Journal of Light Construction*
Thanks to Alan Carson, Carson Dunlop, Associates, Toronto, for technical critique and some of the foundation inspection photographs cited in these articles
More Information on Building Diagnostic Inspections and Repairs
FOUNDATION CRACK EVALUATION discusses detail the process of evaluating foundation cracks and signs of foundation damage by examining the crack size, shape, pattern, and location.
FOUNDATION BULGE or LEAN MEASUREMENTS explains a simple method for determining how much bulge or lean is present in a foundation or wall,
FOUNDATION MOVEMENT ACTIVE vs. STATIC helps determine if the foundation movement is ongoing,
FOUNDATION DAMAGE SEVERITY discusses how we decide the severity of foundation damage and the urgency of further action.
FAILURES by FOUNDATION TYPE & MATERIAL describes the types of foundation damage, cracks, leaks, or other defects associated with each type of foundation material (concrete, brick, stone, concrete block, etc.).
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