VERTICAL CRACKS in BLOCK WALLS - CONTENTS: Inspect & Diagnose Concrete Block Foundation Vertical Cracks or Settlement - in Masonry block or "cinder block" foundation walls or building walls that are above-grade level.
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Vertical cracks in masonry block foundations & walls:
This article describes and evaluates vertical cracking that may appear in some concrete block or masonry block walls or foundation walls. Some readers may use the term "cinder block" - an older form of masonry block wall construction.
This article series explains 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.
Vertical cracks in block foundation walls & expansion and shrinkage cracks in a concrete block wall may occur but are less
common than in some other materials.
Our page top photo shows both vertical cracks and step cracks around a large vent opening in masonry block foundation wall. No header was used across the wall opening top and the two single concrete blocks simply fell-inwards. That movement may explain the step cracks around the top and sides of the opening. Elsewhere in that wall we found significant inwards bulging and horizontal mortar joint cracking, worst at the center of the wall.
At above-left is a vertical crack in a different concrete block wall, also of the type we discuss in this article. [Click to enlarge any image]
Cracks in masonry walls tend to be more severe in the center of walls from external loading and pressure (from
The damage to the wall occurred during backfill - pressure from both the backfill earth itself and the machine operator who drove heavy equipment too close to the foundation wall.
It is possible that that same event caused what appears to be a vertical crack below the window - thought that's unusual: usually backfill produces bulging and horizontal cracks in the mortar joint.
Perhaps the wall was constructed without steel mesh nor other reinforcement.
Question: what is the cause of the vertical cracking in concrete block foundation wall shown in these photos and sketches?
We are considering buying a home that has two vertical cracks in the block basement walls. I have scoured your site and have not found a description that fits our situation. I am providing descriptions, images, a diagram and a potential conclusion of my own.
Could you please take a look and let me know what you think? - anonymous by private email 2017/06/11
Information about the home where these vertical block-wall cracks were observed
Home constructed in 1950 using concrete block foundation and basement walls
Floor-to-ceiling vertical cracks, uniform in crack width, on opposing basement walls
Lateral displacement into or away from the basement: top row of blocks form a step crack that catches your fingernail - approx 1/16" displacement - these blocks are above grade level
There are no apparent cracks in walls or exterior
Doors open and close fine
An addition built over a crawl space was added 20-30 years
Questions about these vertical cracks in the block wall:
Would a strike to the outside wall by machinery, somewhere around the header beam, cause a crack in each wall and the uneven surface?
Interesting vertical cracks in the block walls in your photos. Here I include one of our photos, a closer look at a vertical crack in the masonry block wall of a New York home that was shown at the start of this article. You can see that the crack runs almost-straight vertically through the center of alternating courses of masonry block and through the mortar joints between blocks of the other courses.
I think that this wall cracked in its center as a result of expansion or contraction caused by significant changes in the moisture content of these blocks - but I'm not certain.
In discussing your block wall cracking, I must give this apology in advance: without a detailed onsite inspection and more information, my comments are speculation.
Vertical cracks in any sort of masonry wall (brick, concrete, concrete block, stone) are pretty easy to identify and are shown at VERTICAL FOUNDATION CRACKS - how to identify this type of damage, though complicating their evaluation is that these cracks often appear together with other crack patterns, particularly stair-step cracking in foundations made of brick or masonry block and in a rougher-pattern also in some stone foundation walls.
The causes of vertical cracks are usually traced to vertical dislocation of the foundation footing or entire wall. Details ar at VERTICAL MOVEMENT IN FOUNDATIONS.
A quite-straight crack in a masonry wall or foundation usually is due to shrinkage (concrete), occasionally expansion (brick). Concrete block walls might shrink or expand in response to moisture changes but usually these forces are low, usually occur as slight shrinkage, and rarely appear in the wall below -grade where moisture content is less variable. Thermal expansion can crack brick walls - not something we've seen in concrete block. We discuss these distinctions at SHRINKAGE vs EXPANSION vs SETTLEMENT
Vertical cracks in masonry foundations or walls don't usually appear as the only crack pattern. So you'll want to review other crack patterns and causes explained at BLOCK FOUNDATION & WALL DEFECTS.
Your acute observation that the wall sections across the crack are slightly displaced - one section inwards - is an argument for loading on the outside of the entire wall, provided that the dislocation extends over the height of the wall. If on the other hand the displacement is only at the wall top and is all above grade, that is more-likely due to impact.
The construction of the addition onto this home is worth considering as related to the cracking, just as you suggested. But I don't see how activity to add a crawl space addition on one wall would have pushed both existing foundation walls in the same direction: towards the addition by your sketch. To do that one would have had to move the entire end of the building at once. That's possible but rather unlikely.
Still, digging and driving heavy equipment outside of a building can break a wall; what trips up this reasoning is that in my experience equipment earth loading will usually cause horizontal cracks in the mortar joints of a block wall, often in the wall's top 1/3 assuming backfill was to near the wall top.
Look very carefully at the the wall for bulging - possibly caused by backfill or equipment + backfill during original construction. I'm not sure that there aren't some fine cracks in the horizontal mortar joints in the wall - and some bulging. Our photo of a severely-damaged concrete wall - shown here - includes the most-significant break and dislocation along a roughly-vertical line up through the wall. This wall is collapsing, unsafe, and needs to be reconstructed.
I didn't see such evidence of bulging in your photos but a careful look and measurements might be diagnostic.
Footing settlement over a hinge point: Another cause could be a defect that disturbs both footings under or near the crack - e.g. a pipe or object that ran under the whole structure. This would be more likely if the crack were wider at top than at the floor. We discuss this in an article series starting with BUILDING SETTLEMENT.
A point of impact strike would have trouble breaking BOTH walls at once and usually would show up as damage having a visible center rather than a straight vertical crack.
An impact that hit the whole structure near grade top and pushed the floor structure so that both walls were moved would want to break blocks at joints near the wall top rather than tipping the whole structure and breaking in the pattern you show - I'm presuming from your comments that the wall was backfilled to near its top.
The efflorescence and water stains low on the wall are more-likely leaks that have found their way through the existing crack than a cause.
Follow-up questions on diagnosing these wall cracks
Look carefully into the cracks at the debris and for other signs of their age and history: did this happen during construction or later - that'd be diagnostic. Is there an accumulation of paint in the cracks? Is there an accumulation of dirt?
Are there signs of ongoing movement or recent movement in the foundation such as freshly-broken masonry material whose break edges are more clean? See FOUNDATION MOVEMENT ACTIVE vs. STATIC
Make careful measurements of wall bulging or bowing. IF there is no significant bulge nor lean and more so if the damage is old, the urgency of a costly structural repair is rather low - but there will be a marketing impact at re-sale time. See FOUNDATION BULGE or LEAN MEASUREMENTS
Are there signs of ongoing or significant foundation damage that are likely to require near-term or even immediate and costly repairs? See FOUNDATION DAMAGE SEVERITY
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Diagnosing & Repairing House Structure Problems, Edgar O. Seaquist, McGraw Hill, 1980 ISBN 0-07-056013-7 (obsolete, incomplete, missing most diagnosis steps, but very good reading; out of print but used copies are available at Amazon.com, and reprints are available from some inspection tool suppliers). Ed Seaquist was among the first speakers invited to a series of educational conferences organized by D Friedman for ASHI, the American Society of Home Inspectors, where the topic of inspecting the in-service condition of building structures was first addressed.
Defects and Deterioration in Buildings: A Practical Guide to the Science and Technology of Material Failure, Barry Richardson, Spon Press; 2d Ed (2001), ISBN-10: 041925210X, ISBN-13: 978-0419252108. Quoting: A professional reference designed to assist surveyors, engineers, architects and contractors in diagnosing existing problems and avoiding them in new buildings. Fully revised and updated, this edition, in new clearer format, covers developments in building defects, and problems such as sick building syndrome. Well liked for its mixture of theory and practice the new edition will complement Hinks and Cook's student textbook on defects at the practitioner level.
Masonry structures: The Masonry House, Home Inspection of a Masonry Building & Systems, Stephen Showalter (director, actor), DVD, Quoting: Movie Guide Experienced home inspectors and new home inspectors alike are sure to learn invaluable tips in this release designed to take viewers step-by-step through the home inspection process. In addition to being the former president of the National Association of Home Inspectors (NAHI), a longstanding member of the NAHI, the American Society of Home Inspectors (ASHI), and the Environmental Standard Organization (IESO), host Stephen Showalter has performed over 8000 building inspections - including environmental assessments. Now, the founder of a national home inspection school and inspection training curriculum shares his extensive experience in the inspection industry with everyday viewers looking to learn more about the process of evaluating homes. Topics covered in this release include: evaluation of masonry walls; detection of spalling from rebar failure; inspection of air conditioning systems; grounds and landscaping; electric systems and panel; plumbing supply and distribution; plumbing fixtures; electric furnaces; appliances; evaluation of electric water heaters; and safety techniques. Jason Buchanan --Jason Buchanan, All Movie Review
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, professor, school of structures division, UIUC - University of Illinois at Urbana-Champaign School of Architecture. Professor Wickersheimer specializes in structural failure investigation and repair for wood and masonry construction. * Mr. Wickersheimer's engineering consulting service can be contacted at HDC Wickersheimer Engineering Services. (3/2010)
*These reviewers have not returned comment 6/95
Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
Sinkholes and Sudden Land Subsidence References, Products, Consultants
"A Hole in the Ground Erupts, to Estonia's Delight", New York Times, 9 December 2008 p. 10.
History of water usage in Estonia: (5.7 MB PDF) jaagupi.parnu.ee/freshwater/doc/the_history_of_water_usage_systems_in_estonia.pdf
"Quebec Family Dies as Home Vanishes Into Crater, in Reminder of Hidden Menace", Ian Austen, New York Times, 13 May 2010 p. A8. See http://www.nytimes.com/
"Quick Clay", Wikipedia search 5/13/2010 - http://en.wikipedia.org/wiki/Quick_clay
Florida DEP - Department of Environmental Protection, & Florida Geological survey (http://www.dep.state.fl.us/geology/default.htm) on Florida sinkholes: Effects of Sinkholes on Water Conditions Hernando County, Florida, Brett Buff, GIS in Water Resources, 2008, Dr. David R. Maidment, Photos - Tom Scott, Florida Geographic Survey - Web Search 06/09/2010 - http://www.dep.state.fl.us/geology/geologictopics/jacksonsink.htm
and - http://www.dep.state.fl.us/geology/geologictopics/sinkhole.htm
Lane, Ed, 1986, Karst in Florida: Florida Geological Survey Special Publication 29, 100 p.
Foundation Engineering Problems and Hazards in Karst Terranes, James P. Reger, Maryland Geological Survey, web search 06/05/2010, original source: http://www.mgs.md.gov/esic/fs/fs11.html Maryland Geological Survey, 2300 St. Paul Street, Baltimore, MD 21218
"Frost Heaving Forces in Leda Clay", Penner, E., Division of Building Research, National Research Council of Canada, Canadian Geotechnical Journal, NRC Research Press, 1970-2, Vol 7, No 1, PP 8-16, National Research Council of Canada, Accession number 1970-023601, Quoting from original source
The frost heaving forces developed under a 1 ft. (30.5 cm) diameter steel plate were measured in the field throughout one winter. The steel plate was fixed at the ground surface with a rock-anchored reaction frame. heave gauges and thermocouples were installed at various depths to determine the position and temperature of the active heaving zone. The general trend was for the surface force to increase as the winter progressed. when the frost line approached the maximum depth the force was in excess of 30,000 lb (13,608 KG). Estimates of the heaving pressure at the frost line ranged from 7 to 12 psi (0.49 to 0.84 KG/cm) square during this period. The variation of surface heaving force was closely associated with weather conditions. Warming trends resulting in a temperature increase of the frozen layer caused the forces to decline.
Leda clay slopes in the Ottawa valley are vulnerable to catastrophic landslides. More than 250 landslides, historical and ancient, large and small, have been identified within 60 km of Ottawa. Some of these landslides caused deaths, injuries, and property damage, and their impact extended far beyond the site of the original failure. In spectacular flowslides, the sediment underlying large areas of flat land adjacent to unstable slopes liquefies. The debris may flow up to several kilometres, damming rivers and causing flooding, siltation, and water-quality problems or damaging infrastructure. Geologists and geotechnical engineers can identify potential landslide areas, and appropriate land-use zoning and protective engineering works can reduce the risk to property and people.
Deposits of Leda clay, a potentially unstable material, underlie extensive areas of the Ottawa-Gatineau region. Leda clay is composed of clay- and silt-sized particles of bedrock that were finely ground by glaciers and washed into the Champlain Sea. As the particles settled through the salty water, they were attracted to one another and formed loose clusters that fell to the seafloor. The resulting sediment had a loose but strong framework that was capable of retaining a large amount of water. Following the retreat of the sea, the salts that originally contributed to the bonding of the particles were slowly removed (leached) by fresh water filtering through the ground. If sufficiently disturbed, the leached Leda clay, a weak but water-rich sediment, may liquefy and become a 'quick clay'. Trigger disturbances include river erosion, increases in pore-water pressure (especially during periods of high rainfall or rapid snowmelt), earthquakes, and human activities such as excavation
After an initial failure removes the stiffer, weathered crust, the sensitive clay liquefies and collapses, flowing away from the scar. Failures continue in a domino-like fashion, rapidly eating back into the flat land lying behind the failed slope. The flowing mud may raft intact pieces of the stiffer surface material for great distances.
Kochanov, W. E., 1999, Sinkholes in Pennsylvania: Pennsylvania
Geological Survey, 4th ser., Educational Series 11,
33 p., 3rd printing April 2005, Pennsylvania Department of Conservation and Natural Resources / Bureau of Topographic and Geologic Survey, DCNR Educational Series 11, Pennsylvania Geological Survey, Fourth Series, Harrisburg,
1999 - web search 06/05/2010, original source: http://www.dcnr.state.pa.us/topogeo/hazards/es11.pdf - Quoting from the document introduction: The first 18 pages of this booklet contain an explanation of how sinkholes
develop. In order to tell the sinkhole story, it is important to discuss
a number of related geologic disciplines. The words used to describe sinkholes
and these disciplines may be a bit unfamiliar. However, general explanations
are given throughout the booklet to help clarify their meanings.
Key words are printed in bold type for emphasis. The more important
ones are defined in a Glossary that begins on page 29.
The remaining sections, starting with “Sinkholes in the Urban Environment”
(page 18), deal with sinkholes and their impact on our environment.
This includes recognition of subsidence features and sinkhole repair.
 Sarah Cervone, [web page] data from the APIRS database, Graphics by Ann Murray, Sara Reinhart and Vic Ramey, Vic Ramey is
the editor. DEP review by Jeff Schardt and Judy Ludlow. The web page is a
collaboration of the Center for Aquatic and Invasive Plants, University of Florida, and the Bureau of Invasive
Plant Management, Florida Department of Environmental Protection contact: email@example.com [A primary resource for this article
 Center for Cave and Karst Studies or the Kentucky Climate Center, both at Western Kentucky University
Vanity Fair - web search 06/04/2010 http://www.vanityfair.com/online/daily/2010/06/what-caused-the-guatemala-sinkhole-and-why-is-it-so-round.html
Sinkholes, Virginia Division of Mineral Resources,
Virginia Department of Mines, Minerals and Energy, www.dmme.virginia.gov Virginia Department of Mines, Minerals and Energy Division of Mineral Resources
900 Natural Resources Drive, Suite 500 Charlottesville, VA 22903 Sales Office: (434) 951-6341 FAX : (434) 951-6365 Geologic Information: (434) 951-6342
http://www.dmme.virginia.gov/ divisionmineralresources.shtml - Web search 06/09/2010
Sink Hole & Related Engineering References
Newton, J. G., 1987, Development of sinkholes resulting from man's activities in the eastern United States: US Geological Survey Circular 968, 54 p.
Sinclair, W. C., 1982, Sinkhole development resulting from ground-water withdrawal in the Tampa Area, Florida: U.S. Geological Survey Water-Resources Investigations 81-50, 19 p.
White, W. B., 1988, Geomorphology and Hydrology of Karst Terrains: Oxford University Press, New York, 464 p.
Williams, J. H. and Vineyard, J. D., 1976, Geologic indicators of subsidence and collapse in karst terrain in Missouri: Presentation at the 55th Annual Meeting, Transportation Research Board, Washington, D.C.
Barry F. Beck, A. J. (1999). Hydrogeology and Engineering Geology of Sinkholes and Karst. Rotterdam, Netherlands: A. A. Balkema.
Beck, B. F. (2003). Sinkholes and the Engineering and Environmental Impacts of Karst. Huntsville, Alabama: The American Society of Civil Engineers.
Beck, B. F. (2005). Sinkholes and the Engineering and Envrionmental Impacts of Karst. San Antonio, Texas: The American Society of Civil Engineers.
Tony Waltham, F. B. (2005). Sinkholes and Subsidence, Karst and Cavernous Rocks in Engineering and Construction. Chichester, United Kingdom: Praxis Publishing.
Whitman D., G. T. (1999). Spatial Interrelationships Between Lake Elevations, Water Tables, and Sinkhole Occurence in Central Florida: A GIS Approach. Photogrammetric Engineering and Remote Sensing , 1169-1178.
Sinkholes in Guatemala, Guatemala City, Wikipedia - web search 06/04/2010 - http://en.wikipedia.org/wiki/Guatemala_City
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