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How to Detect, Diagnose, & Evaluate Combinations of Foundation Movement, Bulges, Cracks, Leaning StructAPedia © Enter your search terms Submit search form   Search This Website - InspectAPedia.com

• How to Evaluate and Diagnose Complex Combinations of Foundation Movement Cracks, Bends, Leans, or Shifts in Foundation Walls
• Different causes of foundation leaning, bulging, cracking, creeping, tilting, sliding, or other movements, what they look like, how to fix them.

This chapter of the "Foundation Crack Bible" discusses in detail the recognition of different types and causes of complex or combined building foundation movement and foundation damage. We distinguish among vertical movement, horizontal movement, leaning, tipping, bending, differential and uniform settlement, earthquake and storm damage, and other foundation damage patterns.

Our "Foundation Crack Bible" document, of which this web page is a chapter, describes how to recognize and diagnose various types of foundation failure or damage, such as foundation cracks, masonry foundation crack patterns, and moving, leaning, bulging, or bowing building foundation walls.

Also see FOUNDATION CRACK EVALUATION for a discussion of the diagnosis of specific crack patterns in masonry foundations, and 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 just how much foundation movement is likely to be a concern.

To be used properly, this information must be combined with specific on-site observations at the particular building in order to form a reliable opinion about the condition of that building's foundation. Anyone having concern regarding the structural stability, safety, or damage of a building, foundation or other components, should consult a qualified expert. Photographs of types of foundation cracks and other foundation damage: we have a large library of photographs which we're in process of adding to this document. Pending completion of that work, contact the author if assistance is required.

Combinations of Foundation Wall Movement, Horizontal & Vertical Crack Patterns Occuring Together

Wall bulge and step cracking

Step cracks may also be present in bulged, leaning, or horizontally pushed foundation walls if they were constructed of brick or masonry block, or possibly (though less common) of stone. In fact since the building foundation corners are stronger than the center portions of the foundation wall (the opposing wall at right angle resists movement of the wall being pushed), wall bulges, leans, and cracks tend to occur towards the center of the wall, resulting in step-cracking closer to the ends of the same wall. In the photograph above, frost push has bulged the center of the foundation wall inwards; as the forces of wet earth and or frost pushing on the upper 1/3 of this foundation wall were applied at the center of the wall, the wall bulged inwards and cracked horizontally at the point of most pressure. As the same forces causing this wall to bend were exerted closer to the building corners, the wall cracked in the step-crack pattern clearly marked in this picture by the "repairs" which have been done by filling the cracked joints. If the total amount of wall movement was minor and if the outside source of pressure (water and frost) has been corrected, further repair or reinforcement may not be needed.

Combinations of Foundation Wall Movement During Collapse

In this collapsing foundation illustration, the masonry block wall has bulged inwards, portions are leaning inwards, and some of the courses of masonry blocks have slid horizontally to extend over their neighbors. All three movements are present, and of course this wall needs to be re-built. If you think of a concrete block wall as a stack of "shoe boxes" that you're holding between your hands, and if your friend begins to push inwards on the middle shoe box, you can keep the stack of boxes intact for a while. But eventually your accomplice applies enough horizontal pressure to the center box that the stack begins to bend. When the bending stack of boxes (or concrete blocks) bends inwards far enough to pass a critical point, the whole stack simply pops inwards and collapses. This is how a concrete block wall can collapse suddenly when pressure on it builds past a critical point. (The same wall, if reconstructed with the addition of vertical steel reinforcing rods and concrete will be much stiffer against the same forces.)

Combinations of Building Foundation Movement due to Earthquake, Flood, or Storm Damage

Vertical movement due to earthquake: The Northridge Earthquake in Los Angeles, California in January 1994 caused extensive damage as well as fatalities when buildings were shifted off of their foundations, leading to catastrophic collapse in some cases. This photograph taken at Northridge Meadows, a site of some of the worst fatalities, shows a section of building that collapsed straight down, compressing the first floor (and some occupants) to just a few inches. The left portion of the photo shows a third floor balcony aligned with the second floor balcony of a building segment that did not collapse. Earthquake resistant construction has as a primary objective to prevent just this sort of collapse, as an effort to reduce the number of injuries and fatalities from an earthquake./P>

Horizontal movement due to earthquake damage: The Northridge Earthquake in January 1994 also caused extensive damage when its lateral thrust caused some buildings buildings to be shifted off of their foundations. This photograph shows an easy-to-determine case of significant lateral movement of a wood frame structure. Often an improperly secured crawl space cripple wall simply leaned over, levering the building to one side for a distance equal to the height of the collapsing (cripple wall). In this case the collapse was of a wood-framed supporting wall, not a masonry foundation.

Combination of movements due to earthquake damage is demonstrated by this photograph of an unreinforced stone masonry foundation and wall home in California. Unreinforced concrete structures are no longer permitted by California building codes for construction in areas of earthquake risk.

Flood damaged building foundation walls: just as earth pressure or the increased pressure from wet earth can lead to foundation damage or even collapse, flooding around buildings can lead to foundation damage or collapse from a combination of pressure on foundation walls and perhaps loosening of supporting soils. In flood prone areas local building codes may call for the installation of flood ports on building foundation walls to reduce the risk of building collapse. The principle of the flood vent is simple: in response to high water surrounding a building the flood vent opens to permit water to enter the building basement or crawl space, thus equalizing pressure on both sides of the foundation and reducing the chances of foundation collapse.

Examples of other step cracks occurring in masonry walls or masonry foundations

Other step cracks will of course also occur in building masonry block foundation walls and in brick masonry walls that are not leaning or bulging particularly, where frost or settlement have been causing an "up and down" movement in the foundation or footing. We will also encounter step cracks where earth pressure or frost have pushed such a wall horizontally, breaking the masonry courses near a corner or wall-end in a stair-step pattern such as we see in this little example of water and frost damage to a brick retaining wall.

FOUNDATION DIAGNOSIS
EARTHQUAKE DAMAGED FOUNDATIONS
FOUNDATION CONSTRUCTION TYPES
FOUNDATION INSPECTION METHODS
FAILURES by FOUNDATION TYPE & MATERIAL
  Block Foundation & Wall Defects
  Brick Foundation & Wall Defects
  Brick Thermal Expansion Cracking
  Concrete Poured Foundation Wall & Slab Defects
  Concrete Pre-cast Foundation Defects
  Stone Foundation Defects
  Wood Foundation Defects
FAILURES by FOUNDATION MOVEMENT TYPE
  BULGED vs. LEANING FOUNDATIONS
  COMBINATIONS OF FOUNDATION MOVEMENT
    Bulge & step cracks
    Earthquake Damage to Foundations
    Flood Damage to Foundations
    Foundation Movement During Collapse
    Other Foundation Step cracks
  HORIZONTAL MOVEMENT IN FOUNDATIONS
    Bulging, Leaning & Sliding Wall
    Horizontal Foundation Creep
    Horizontal Movement & step cracks in brick
    Impact Damage to Foundations
    Thermal Expansion Cracking in Brick
  VERTICAL MOVEMENT IN FOUNDATIONS
    Diagonal Cracks in Concrete Foundations
    Diagonal Step Cracking in Masonry
    Differential vs. Uniform Settlement Cracks
    Leaning or Tipping Buildings
    Uniform Width vs. Tapered Foundation Cracks
    Vertical Cracks
FLOOD DAMAGE TO FOUNDATIONS
FOUNDATION DEFECTS OF OMISSION
FOUNDATION CRACK EVALUATION
  DIAGONAL FOUNDATION CRACKS
  HORIZONTAL FOUNDATION CRACKS
  SHRINKAGE vs EXPANSION vs SETTLEMENT
  Sinkholes & Building Damage
  VERTICAL FOUNDATION CRACKS
FOUNDATION BULGE or LEAN MEASUREMENTS
FOUNDATION DAMAGE SEVERITY
FOUNDATION DAMAGE REPORTS
FOUNDATION INSPECTION STANDARDS
FOUNDATION MOVEMENT ACTIVE vs. STATIC
FOUNDATION REPAIR METHODS
  Bulged foundation Repairs
  Crack Repair Methods
  Horizontal Movement Repairs
  Shrinkage Crack Repairs
  Vertical Movement Repairs
SITE FACTORS AFFECTING FOUNDATIONS
SLAB CRACK EVALUATION
  Control Joint Cracks in Concrete
  Freezing & Water Damage
  Frost Heave/Expansive Soil Cracks in Slabs
  Seal Cracks by Polyurethane Foam Injection
  Seal Cracks in Concrete, How To
  Settlement Cracks in Slabs
  Settlement Cracks vs. Frost Heaves
  Settlement Cracks vs. Shrinkage Cracks
  Shrinkage Cracks in Slabs
  Shrinkage Cracks Along Foundation Walls
  Standards for Repair of Cracks in Floors
WATER ENTRY in BUILDINGS
  SUMP PUMPS GUIDE
ADDITIONAL READING
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FOUNDATION DIAGNOSIS Chapter Index

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FOUNDATION DIAGNOSIS - how to inspect and diagnose foundation problems, in-depth diagnosis, and evaluation of all types of structural and non-structural cracks in residential foundations [Brick, Concrete, Masonry Block, Stone]
EARTHQUAKE DAMAGED FOUNDATIONS - examples of earthquake-damaged building foundations
FOUNDATION CONSTRUCTION TYPES - identify different foundation types, construction materials, effects of sequence of construction
FOUNDATION INSPECTION METHODS - what to look for when inspecting any building foundation
FAILURES by FOUNDATION TYPE & MATERIAL- unique failure characteristics of each foundation material
  Block Foundation & Wall Defects
  Brick Foundation & Wall Defects
  Brick Thermal Expansion Cracking
  Concrete Poured Foundation Wall & Slab Defects
  Concrete Pre-cast Foundation Defects
  Stone Foundation Defects
  Wood Foundation Defects
FAILURES by FOUNDATION MOVEMENT TYPE -recognize & diagnose types of foundation damage by the nature of foundation movement
  BULGED vs. LEANING FOUNDATIONS - distinction of foundation bulging from foundation leaning has important implications for stability
  COMBINATIONS OF FOUNDATION MOVEMENT - the real world of foundation cracks and movement: often more than one force is at work
    Bulge & step cracks
    Earthquake Damage to Foundations
    Flood Damage to Foundations
    Foundation Movement During Collapse
    Other Foundation Step cracks
  HORIZONTAL MOVEMENT IN FOUNDATIONS - detection, causes, effects, evaluation of horizontal or lateral foundation movement; hillsides
    Bulging, Leaning & Sliding Wall
    Horizontal Foundation Creep
    Horizontal Movement & step cracks in brick
    Impact Damage to Foundations
    Thermal Expansion Cracking in Brick
  VERTICAL MOVEMENT IN FOUNDATIONS - detection, causes, effects, evaluation of vertical foundation movement, differential settlement
    Diagonal Cracks in Concrete Foundations
    Diagonal Step Cracking in Masonry
    Differential vs. Uniform Settlement Cracks
    Leaning or Tipping Buildings
    Uniform Width vs. Tapered Foundation Cracks
    Vertical Cracks
FLOOD DAMAGE TO FOUNDATIONS - examples of flood damaged foundations, flood damage case analysis: were these cracks due to flooding?
FOUNDATION DEFECTS OF OMISSION - recognize things that were left out, like footings, reinforcement, soil compaction, during foundation construction
FOUNDATION CRACK EVALUATION- recognize & diagnose types of foundation cracks, movement, damage, by the size, shape, location, pattern of cracks
  DIAGONAL FOUNDATION CRACKS - causes and significance of diagonal foundation cracks, varies by foundation type & material
  HORIZONTAL FOUNDATION CRACKS - causes and significance of horizontal foundation cracks, varies by foundation type & material
  SHRINKAGE vs EXPANSION vs SETTLEMENT - which foundation materials shrink, which expand, & their characteristic crack patterns
  Sinkholes & Building Damage - sinkhole recognition, significance, cause, underlying geology, areas where sinkholes are worst
  VERTICAL FOUNDATION CRACKS - - causes and significance of vertical foundation cracks, varies by foundation type & material
FOUNDATION BULGE or LEAN MEASUREMENTS - procedure for documenting the amount of lean or bulge in a foundation or other building wall
FOUNDATION DAMAGE SEVERITY - rules of thumb for deciding how much foundation movement requires further action
FOUNDATION DAMAGE REPORTS - how to report foundation inspection results and damage
FOUNDATION INSPECTION STANDARDS - definition of scope of what a foundation inspector
FOUNDATION MOVEMENT ACTIVE vs. STATIC - determine if foundation movement was a one-time event or an ongoing problem
FOUNDATION REPAIR METHODS - catalog of methods used to repair damaged foundations and masonry building walls
  Bulged foundation Repairs
  Crack Repair Methods
  Horizontal Movement Repairs
  Shrinkage Crack Repairs
  Vertical Movement Repairs
SITE FACTORS AFFECTING FOUNDATIONS - drainage, rock, soil compaction, slope or grading, bedrock, sloping bedrock, proximity to roads
SLAB CRACK EVALUATION - recognize and diagnose different types of slab or concrete floor cracks and movement
  Control Joint Cracks in Concrete - what are control joints, why they are needed, what happens when they're omitted; are they structural?
  Freezing & Water Damage - recognize frost and water damage to concrete slabs, distinguish from other crack types
  Frost Heave/Expansive Soil Cracks in Slabs - distinguish between frost damage and expansive clay soil damage to slabs
  Seal Cracks by Polyurethane Foam Injection - stop basement or crawl space leakage
  Seal Cracks in Concrete, How To - products and methods used to seal or repair cracks in poured concrete walls, foundations, floors, & slabs.
  Settlement Cracks in Slabs - recognize slab settlement, assess risk, assess potential impact on structure
  Settlement Cracks vs. Frost Heaves - how to tell the difference between frost heaves and foundation settlement; does it matter?
  Settlement Cracks vs. Shrinkage Cracks - critical identification of shrinkage cracks (non-structural) compared with foundation movement
  Shrinkage Cracks in Slabs - causes, prevention, assessment of concrete slab shrinkage cracks
  Shrinkage Cracks Along Foundation Walls - why do we see a gap between a poured concrete slab and its abutting foundation wall?
  Standards for Repair of Cracks in Floors - when does a floor or slab crack need to be repaired? why?
WATER ENTRY in BUILDINGS
  SUMP PUMPS GUIDE - how a sump pump can avoid foundation damage and reduce building water entry
ADDITIONAL READING

More Information

Technical Content Reviewers for Foundation Crack and Movement Damage Evaluation, Diagnosis, & Reporting

• Daniel Friedman - ASHI (1986-2006) - author of this website and article, building failures researcher.
• 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
• Terry Carson - ASHI
• Mark Cramer - ASHI
• JD Grewell, ASHI
• Duncan Hannay - ASHI, P.E. *
• Bob Klewitz, M.S.C.E., P.E. - ASHI
• Ken Kruger, P.E., AIA - ASHI
• Bob Peterson, Magnum Piering - 800-771-7437 - FL*
• Arlene Puentes, ASHI, October Home Inspections - (845) 216-7833 - Kingston NY
• Greg Robi, Magnum Piering - 800-822-7437 - National*
• Dave Rathbun, P.E. - Geotech Engineering - 904-622-2424 FL*
• Ed Seaquist, P.E., SIE Assoc. - 301-269-1450 - National
• Dave Wickersheimer, P.E. R.A. - IL*
• *These reviewers have not returned comment 6/95

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