Question? Just ask us!
Free Encyclopedia of Building & Environmental Inspection, Testing, Diagnosis, Repair
InspectAPedia ® Home
STRUCTURAL INSPECTIONS & DEFECTS
AGE of a BUILDING - how to determine
BRICK FOUNDATIONS & WALLS
CHIMNEY INSPECTION DIAGNOSIS REPAIR
COLD POUR JOINTS, CONCRETE
COLUMNS & POSTS, DEFECTS
DISASTER BUILDING INSPECTION & REPAIR
EARTHQUAKE DAMAGED FOUNDATIONS
FLOOD DAMAGE ASSESSMENT, SAFETY & CLEANUP
FLOOD DAMAGE TO FOUNDATIONS
FOOTING & FOUNDATION DRAINS
FOOTINGS EXPOSED, Repair Methods
FOUNDATION BULGE or LEAN MEASUREMENTS
FOUNDATION CONSTRUCTION TYPES
FOUNDATION CONTRACTORS, ENGINEERS
FOUNDATION CRACKS & DAMAGE GUIDE
FRAMING DAMAGE, INSPECTION, REPAIR
GRADING, DRAINAGE & SITE WORK
GUTTERS & DOWNSPOUTS
INSECT INFESTATION / DAMAGE
MOBILE HOMES, DOUBLEWIDES, TRAILERS
MODULAR HOME CONSTRUCTION
MOISTURE CONTROL in BUILDINGS
RETAINING WALL DESIGNS, TYPES, DAMAGE
RETAINING WALL GUARD RAILINGS
STRAW BALE CONSTRUCTION
STRUCTURAL DAMAGE PROBING
STRUCTURAL WOOD ASSESSMENT
THERMAL EXPANSION of MATERIALS
TIMBER FRAMING, ROT
WATER BARRIERS, EXTERIOR BUILDING
WATER ENTRY in BUILDINGS
WINTERIZE A BUILDING
Diagonal foundation cracks: diagnosis & repair: this chapter of the Foundation Crack Bible discusses in detail the process of evaluating foundation diagonal foundation cracks, step cracks, and related signs of foundation movement or damage. Diagonal foundation cracks and movement are discussed by type and location of the cracks and their common causes. Foundation cracks, which are signs of foundation damage, can mean very different things depending on the material from which a foundation is made, the location, size, and shape of the foundation crack, and other site observations.
Green links show where you are. © Copyright 2013 InspectAPedia.com, All Rights Reserved.
Typical Diagonal Crack Patterns in Building Foundations & Walls
These crack patterns form clues to help diagnose the probable cause of diagonal foundation cracks in buildings:
Note that often at these foundation failures cracks are visible both outside and inside, but outside they may be covered by backfill.
For detecting evidence of sink holes in an area by visual inspection see Sink Holes: Can X-Ray Vision [Advanced Building & Building Site Inspection Techniques] Warn of Sink Holes? in Florida or elsewhere
Typical repairs for diagonal shrinkage cracks in a poured concrete foundation wall include the following steps
1. Assess and confirm the type of foundation cracking that has occurred so that we understand its cause - since knowing the cause of a crack helps understand the probability of future movement or damage - that is, confirm that we're looking at a shrinkage crack - something that occurred at or close to the time of construction, not a crack that occurred as a result of stresses, loads, or building movement.
2. Assess any impact of the diagonal foundation crack on the structure or its stability. For the diagonal shrinkage crack above it is unlikely that there has been any measurable impact on the rest of the building structure.
But because multiple forces or stresses can be at work at a building at the same time, a shrinkage cracked foundation might also show signs of settlement or actual movement. If this crack also showed signs of ongoing or cyclic building movement, such as due to frost pressure, thus converting it into a structural crack, we'd expect to see breakage across that discontinuous point in the crack shown in our photo, and we might also see lateral dislocation - that is, the foundation wall on the two sides of the crack would no longer be flush. And if there is ongoing settlement we'd expect the crack to be wider at its top than at its bottom (in most cases).
3. Seal the diagonal shrinkage crack against water leakage. If the crack is confirmed to be only due to concrete shrinkage, and to stop water leaks through the foundation, an expert might recommend sealing using epoxy injection. The appeal of that approach is that the cost is much less than a foundation waterproofing effort involving exterior excavation.
Watch out: all foundation waterproofing solutions should begin with an identification of the source of water entry and steps to correct it outside if at all possible. The most common sources of foundation leaks are improper handling of roof runoff or surface runoff - problems that can often be corrected without digging up the foundation. See WATER BARRIERS, EXTERIOR BUILDING and WATER ENTRY in BUILDINGS.
Diagonal Step Cracking in Concrete block or Brick Walls Caused by Vertical Movement - Structural Damage
Typical repairs for diagonal shrinkage cracks in a concrete block foundation wall include the following steps
1. Assess and confirm the type of foundation cracking that has occurred in the block foundation so that we understand its cause - since knowing the cause of a crack helps understand the probability of future movement or damage. For the foundation damage shown in our photo above we suspect severe frost pressure on the wall combined with footing heaving or settlement, but we won't be confident about that analysis before inspecting the rest of the building and the building exterior and site.
2. Assess any impact of the diagonal foundation crack on the structure or its stability. For the concrete block foundation diagonal crack above there is no question that the crack involves significant structural damage, and it's likely that an expert on site will recommend reconstruction of the wall.
But before supporting the structure, removing the wall, and rebuilding this section of the foundation, it makes sense to form a complete picture of the sources of movement and damage. For example, the foundation footings may have been set on poorly prepared soil or on fill, there may be roof or surface runoff problems to correct, and we may also need to install a working foundation drainage system.
3. Repair (or rebuild) the foundation. A crack such as the block wall damage shown above should not simply be sealed with caulk or epoxy. Repairs are needed.
Watch out: even though this wall will probably be rebuilt, as for the concrete foundation discussed earlier, all foundation waterproofing solutions should begin with an identification of the source of water entry and steps to correct it outside if at all possible. The most common sources of foundation leaks are improper handling of roof runoff or surface runoff - problems that can often be corrected without digging up the foundation. See WATER BARRIERS, EXTERIOR BUILDING and WATER ENTRY in BUILDINGS.
Also see FOUNDATION BULGE or LEAN MEASUREMENTS which explains a simple method for determining how much bulge or lean is present in a foundation or wall, then see FOUNDATION MOVEMENT ACTIVE vs. STATIC which helps determine if the foundation movement is ongoing, and see FOUNDATION DAMAGE SEVERITY for a discussion of how we evaluate the significance of evidence of foundation movement.
Frequently Asked Questions (FAQs) about diagonal foundation cracks or step cracking in block foundations
Question: How can we distinguish a diagonal structural crack from a cold pour joint in a poured concrete foundation wall?
I am hoping you can help me out here, the home inspector was not very helpful to me for this one. I have attached an image of the foundation cracks in the basement, I am wondering if you can help me identify if there is any structural problems. The outside of the wall is backfill. Thank you so much for your help! - C.C. 9/5/12
Reply: Unfortunately your photos were quite blurry and small, making any detailed examination impossible. I cannot see if you are actually showing photos of actual foundation cracking (such as due to settlement or movement) or if in fact we are looking at foundation wall leak stains along cold pour joints (COLD POUR JOINTS, CONCRETE).
I also see what looks like leak stains along some of these cracks - or joints. Water leakage through a poured concrete foundation wall can indeed occur at all types of cracks and also occurs at some cold pour joints as well as occasionally at form ties.
Reader Follow up:
Thank you SO much for your detailed response.
They are actual cracks, and I believe there are some white residue left on the walls (possibly efflorescence ?)
Also, the left side of the wall seems like it's a little bent outwards and the right side is bent inwards (think concave and convex).
Is that signs of bulging?
OK so when we know there are cracks in a foundation wall we need to know:
FOUNDATION CRACK EVALUATION discusses evaluating foundation damage by examining concrete crack size, shape, pattern, and location. If inspection confirms that the foundation wall is actually leaning or bulging, particularly confirming that it was not built in that position, then movement has occurred and an accurate diagnosis is important in deciding what repair work, if any, is needed.
Sharp photos of these foundation cracks and patterns would be helpful and would permit some comment, but they are never a substitute for an onsite inspection by an expert. In my experience, the onsite expert almost always finds important additional information that simply was not apparent to a homeowner nor to others.
Reader Follow-up - Nine Diagnostic Photos of Diagonal Foundation "Cracks" that may be cold pour joints
Here are some more pictures. Hopefully you can offer your experience and shed some light on the situation
In the photos below (images were lab-enhanced from as-received) water leak stains are plain at form ties (photo below left, left side), at the floor/wall juncture, and at the diagonal cracks.
Your two photos below offer closer views that look to me like cold pour joints that were leaking.
Your last two photos (below) illustrate an unusual number of unusually close together diagonal foundation crack patterns, nearly all of which have also been leaking.
Even where I find cold pour joints in foundation walls, the only time I see so many such marks so close together is in a poured concrete foundation that was mixed by hand or set in place using many small-quantity concrete pours with enough time delay between each successive pour that there was poor bonding between them. More diagnostic examples are at COLD POUR JOINTS, CONCRETE.
Certainly the diagonals would appear to "contradict" one another in their indications of directions of foundation movement or settlement- a further argument for cold pour joints and either some very unusual site conditions during construction or amateur workmanship.
You didn't say where this home is located nor if it's in an earthquake zone. But while we see other close-set structural cracks in areas of earthquake damage, it would be unusual for a severely earthquake-damaged building to show vertical and diagonal foundation cracks with absolutely no lateral movement or dislocation.
I would like to examine some really sharp close-up photos of some of those crack areas in order to look for classic cold pour joint details in comparison with cracks due to shrinkage, loading, structural movement, but I SPECULATE from the crack pattern, location, even the contradicting directions of cracks in nearby wall sections, that these are leaky cold pour joints.
These walls look as if an amateur concrete mason built the foundation out of a large number of small pours.
The house is only 8 years old. The grading outside is nothing too unusual. The roof has proper drainage as well. I went to a friends house who is in the same row and he doesn't have that problem. do you think a crack fix from outside and a vapor barrier outside of the foundation will prevent leakage for good? When i told people about my worries, That solution was what I have been told by multiple people. -C.C.
C.C., before choosing a "repair" we must be confident that we understand the problem - otherwise it's likely to be money wasted.
At WATER ENTRY in BUILDINGS we provide a series of articles detailing approaches to basement waterproofing, starting with the simple, inexpensive basics but also including the use of excavation, geotextiles, etc.
Questions & answers or comments about how to diagnose & repair diagonal or step cracking in building foundations.
Ask a Question or Enter Search Terms in the InspectApedia search box just below.
Technical Reviewers & References
Related Topics, found near the top of this page suggest articles closely related to this one.