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• How to Distiguish Foundation Bulging vs. Leaning Movement by Type & Location of Cracks & Bends in Foundation Components
• Different causes of foundation leaning, bulging, cracking
• How to Evaluate and Diagnose Foundation Movement by Type & Location of Cracks, Bends, Leans, or Shift in Foundation Components

This chapter of the "Foundation Crack Bible" discusses in detail How to Distiguish Foundation Bulging vs. Leaning Movement by Type & Location of Cracks & Bends in Foundation Components. 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.

How to distinguish between a "bulged" foundation wall and a "leaning" foundation wall, and why we care

Why distinguish between leaning and bulging foundation walls? We care about the distinction between leaning and bulging because understanding the location and pattern of foundation wall cracking or movement may help us diagnose its cause and thus may help us understand what actions are needed to stop further foundation movement or perhaps to decide on a course of repair or reinforcement of the wall. For example, recognizing that a foundation wall has bulged inwards at about the depth of the frost line at a building may tell us that the root cause of that particular foundation movement was frost pressure from spillage of roof runoff too close to and along the building wall. The same forces produce different effects on poured concrete walls compared with masonry block, brick, or stone walls Even a concrete wall which is bulged is likely to be cracked horizontally, though perhaps not in such a straight line. But a bulged reinforced concrete wall would be very rare unless perhaps the concrete wall bulged, or its forms bulged, during the time that the concrete was being poured and was still wet. It's more likely that a reinforced concrete wall will be caused to lean or to shift horizontally while a masonry unit wall or stone wall is likely to be bulged and cracked by the same external forces.

Characteristics of a bulging foundation wall

If our measurements anywhere between the floor and the top of the wall is greater than the distance measured (wall to string) at the floor bottom and at the wall top then the wall is "bulged" inwards at that point. If the wall is masonry block in construction we'd expect to see horizontal cracks in one or mortar joints in the bulged area, with the widest horizontal crack at or close to the point of greatest inward bulge. For details of a simple foundation bulge or lean measurement procedure using just string and a ruler, see FOUNDATION BULGE or LEAN MEASUREMENTS

Characteristics of a leaning foundation wall

If all of our measurements of inwards movements in the foundation wall increase in distance (wall to string), from floor up towards the top of the wall, the wall is leaning inwards. In this case we'd expect to not see horizontal cracks (if the wall is masonry block, for example). Watch out, in some cases a foundation wall may not lean in the direction you expect. For example a reinforced masonry block wall or poured concrete wall which has been pushed inwards by earth loading might move inwards at the bottom of the wall rather than at the top. The bottom of the wall will have been pushed in to the building basement or crawl space and the top may actually begin to lean out and may even become visible outside, protruding out past the building framed wall. (Earthquake damage which shifts a building off of its foundation can also produce something that looks like and can be mistaken for this condition.)

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FOUNDATION CRACKS & DAMAGE GUIDE - 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

• "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
• 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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