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• How to Evaluate the Significance or Amount of Foundation Movement when a foundation is leaning, bulging, bowing, or settling
• Extent of foundation damage
• Photographs of foundation crack patterns

How to Evaluate the Significance or Amount of Foundation Movement when a foundation is leaning, bulging, bowing, or settling. This document 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.

Types of foundation cracks, crack patterns, differences in the meaning of cracks in different foundation materials, site conditions, building history, and other evidence of building movement and damage are described to assist in recognizing foundation defects and to help the inspector separate cosmetic or low-risk conditions from those likely to be important and potentially costly to repair. © Copyright 2009 Daniel Friedman, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use links 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.

FOUNDATION DAMAGE SEVERITY - How to Evaluate the Significance or Amount of Foundation Movement when a foundation is leaning, bulging, bowing, or settling

The photo above shows a cracked, bulged, leaning stone foundation wall at the edge of an embankment - a condition we discuss further at this website.

• Historical data is a key observation or data that needs to be collected to assess the significance of any evidence of foundation movement
• New or sudden foundation movement: If foundation cracking or movement is new, recent, or sudden: serious, prompt action is needed and you should consult an expert, in particular if the amount is more than trivial. Trivial movement would be the discovery of a hairline crack (less than 1/16" in width) or a shrinkage crack in a building foundation wall or floor slab. A word of caution: sometimes a crack has been present for a long time at a building but has simply not been noticed by the building owner or occupants. The first time such a crack is seen it may be mistaken for "new" and "sudden" when that's not the case. See our discussion of SHRINKAGE vs EXPANSION vs SETTLEMENT.
• Recurrent foundation cracking or movement: action is probably needed since recurrent movement can lead to cumulative damage to some structures even if the amount of movement is not great. In particular, if you have made cosmetic repairs to a foundation or to plaster or drywall finished areas above and supported by such a foundation you may see that the cracks you repaired have simply recurred.
• Long term, continuing, but slow foundation movement: action may be needed, particularly if the effects of long term foundation movement are cumulative.
• Initial foundation cracking or other limited damage occurring at time of construction such as foundation cracks in a masonry block wall which occurred during backfill may not need other than cosmetic repairs, in particular if there is no evidence of subsequent foundation movement and still more likely if the initial damage and amount of movement was minor (say less than 1/2" of inwards foundation wall bulge in the cracked areas.)
• Foundation damage due to being struck: in this case the foundation will certainly need repair if the damage to it was extensive with collapsed or severely dislocated components. Trivial foundation damage, say cracking a masonry block on the corner of a garage with no basement below, is less likely to be significant.
• Initial foundation settlement may not require additional repair. A hairline to 1/16" vertical crack in a concrete wall or similar dimension step cracking in a masonry block wall may need cosmetic and sealant repair (to reduce leakage through the wall, but if the initial amount of settlement was very small and is not ongoing, repair is unlikely to be needed.

These examples of foundation damage are almost always very important and need expert attention

• Dislocated gas, plumbing, or electrical wiring or piping: NOTE: ANY foundation damage or crack associated with significant displacement of original structural or mechanical (gas/sewer lines) components is likely to be significant. Even slight displacement is significant if mechanical systems may be unsafe (earthquake). Dislocated gas lines means gas leaks are likely and there is serious damage of catastrophic explosion. Vacate the property, and immediately call the gas company from a telephone that is not exposed to gas fumes.
• Dislocated or broken structural connections such as a building which has shifted off of its foundation or has broken sill bolts or straps connecting the foundation to the building framing needs expert investigation and repair.
• Bulging foundation walls in response to area flooding are at risk of collapse; temporary support of the building and other measures to relieve stress on the foundation may be needed. Do not delay in seeking expert advice in this situation.
• This list is not complete. Suggestions welcomed.

Some simple "rule of thumb" for evaluating the seriousness of foundation damage

Amount, type, & direction of foundation movement

• Bulging brick - if broken bond courses, very serious/dangerous (1/3 "rule"-A. Carson; author opinion: this needs clarification. 1/3 of wall thickness looks like much too much movement to allow--DF.)
• Bulging masonry block - risk of collapseVertical & horizontal dislocation - depends on amount

The importance of the amount of foundation movement varies

• Wall height, type of construction, materials
• Implications for building: structure-pulled framing apart?
• Site factors which increase risk: earth loading, water

Climate, seismic, & other local foundation structural requirements

Earthquake design requirements for reinforcement

Cold-climate design requirements for reinforcement, drainage, frost protection

Storm/High-wind (and earthquake) design requirements for connections to framing (not considered here)

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Other Expert Views regarding Evaluating Foundation Crack Size or Extent of Movement
StructAPedia ^©

British Royal Institute of Chartered Surveyors, RICS - Degree of Damage - per W.H. Ransom (RICS)

• Very slight/slight single, isolated cracks - Fine cracks, <5mm (.3") wide, slight sticking windows/doors
• Moderate - 5-15mm (.2"-.6") wide, point up brick, some local replacement, doors/windows stick, pipes may break, not weather tight
• Severe/very severe - > 15mm (.6") to > 25mm (1"), walls likely to lean, bulge, may require shoring; beams may lose bearing; windows distort, glass may break, pipes probably break. External repairs needed, partial or complete rebuild.
• Multiple small cracks, leaning, shifting can be serious too.

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FOUNDATION DAMAGE SEVERITY TERMS - How to Characterize the Severity of Foundation Damage
StructAPedia ^©

Based on multiple national ASHI seminar polls conducted by the author - American Society of Home Inspectors (ASHI)

Minor, single, isolated, cosmetic, marketing concerns

• Cracks, hairline to 1/16" horizontal
• Cracks, hairline to 1/8" vertical and step; [1/4" ? per Alk - note that this is an unsubstantiated opinion]]
• Cracks in slabs, hairline to 1/8", not extending into foundation

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Modest foundation damage, monitoring appropriate

• Horizontal bulge < 1.5", no signs of other significant damage
• Leaning wall < 1/3 of wall thickness, from wall base (In author's opinion 1/3 is way too much movement to tolerate; a conventional thickness masonry block wall that leans in one inch over an 8' ht. (or maybe 1.5" per some surveys) might be monitored depending on other site conditions, history, etc. Walls buckled in or leaning more than 1" (or 1.5" in some jurisdictions) should be professionally evaluated further and may require near-term or even immediate repair; Walls buckled in or leaning an inch or less should be monitored.
• If the cracks are old, with no sign of continuing/recurrent movement - the inspector is more likely to accept monitoring rather than requiring repair.
• Cracks described by "wavy mortar" which were caused by damage during backfill while mortar was still "green" or soft (un-cured) and which are not accompanied by other signs of ongoing or additional movement, can be attributed to a single-event and may not require repair (depending on total amount of wall dislocation).

Significant, expert foundation assessment needed. Foundation repair may be needed

• >1.5" horizontal bulge/lean or lateral dislocation >1/4".
• Signs of active, recent, recurrent movement (may be seasonal or ongoing)
• Sudden appearance of cracks, particularly in areas known to have sink-holes (e.g. some areas of the U.S. such as in Florida.) requires immediate assessment.
• Signs of repeated repairs to foundation or interior
• Cracks 1/4" [ 3/8" per Alk] & larger
• Investigate any finding of which the inspector is uncertain or inexperienced.

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FOUNDATION CRACKS & DAMAGE GUIDE
INTRODUCTION
FOUNDATION INSPECTION METHODS
SITE FACTORS AFFECTING FOUNDATIONS
FOUNDATION CONSTRUCTION TYPES
FAILURES by FOUNDATION TYPE & MATERIAL
FOUNDATION DEFECTS OF OMISSION
FOUNDATION CRACK EVALUATION
  CRACK MONITORING Methods
  DIAGONAL FOUNDATION CRACKS
  HORIZONTAL FOUNDATION CRACKS
  SHRINKAGE vs EXPANSION vs SETTLEMENT
  Sinkholes & Building Damage
  Thermal Expansion Cracking of Brick
  VERTICAL FOUNDATION CRACKSSLAB CRACK EVALUATION
FAILURES by FOUNDATION MOVEMENT TYPE
FOUNDATION BULGE or LEAN MEASUREMENTS
FOUNDATION MOVEMENT ACTIVE vs. STATIC
FOUNDATION DAMAGE SEVERITY
FOUNDATION DAMAGE SEVERITY TERMS
FOUNDATION DAMAGE REPORTS
  Crack Monitoring Methods
FOUNDATION REPAIR METHODS
ADDITIONAL READING
FOUNDATION INSPECTION STANDARDS

• 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
• Aaron Kuertz aaronk@appliedtechnologies.com, with Applied Technologies regarding polyurethane foam sealant as other foundation crack repair product - 05/30/2007
• 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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