How to Diagnose & Evaluate Diagonal Foundation Cracks InspectAPedia® -
How to Evaluate Diagonal Foundation Cracks
Photographs of types of foundation cracks
InspectAPedia offers impartial, unbiased advice without conflicts of interest.
We will block advertisements which we discover or readers inform us are associated with bad business practices,
false-advertising, or junk science. Our contact info is at
InspectAPedia.com/Contact.htm.
This chapter of the "Foundation Crack Bible" discusses in detail the process of evaluating foundation
diagonal foundation cracks, step cracks, and signs of foundation damage. Foundation cracks and movement are discussed by type and location of foundation cracks,
vertical foundation cracks, horizontal cracks, and diagonal foundation cracks, and shrinkage cracking.
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.
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.
DIAGONAL FOUNDATION CRACKS - Diagonal & Step Crack Patterns in Building Foundations
This settlement crack probably occurred during initial footing settlement.
Notice that it is wider at the top than the bottom of the
crack. This suggests that the footing to the left or right of the crack has moved downwards, with further downwards movement as we move
further from the crack itself.
If this is new construction and the crack does not change in width the site conditions may have stabilized.
Clues to help diagnose the probable cause of diagonal foundation cracks in buildings:
From corner towards adjacent opening, wider at top than bottom - often due to foundation settlement, expansive clay soil, frost damage, or
damage from a shrub/tree close to the foundation wall.
Under a ground floor window, from sill to ground, sill bowed up - often due to foundation heave, clay soil, frost, shallow or absent footings
In the foundation wall anywhere, wider at bottom than top - settlement under building
At building corners in cold climates - frost heave, frost lensing, shallow footings, water problem, or insufficient backfill. In a typical
raised ranch with a garage located in part of the basement, and with the garage entering at one end of a home, we often find step cracks
in the front and rear foundation walls only on the garage-end of the home. These cracks may correspond to some related observations: (1) there
may be less backfill against the front and rear foundation walls where a garage entry is located between them; (2) the reduction in backfill combined
with an un-heated garage may expose these building corners to more frost damage; (3) if a building downspout or gutter defect spills roof
drainage against the building wall, these forces will often combine to make more severe frost cracks appear on the garage-entry end of the home.
Vertical or diagonal crack which over a short time - settlement over sink holes- serious, open suddenly after rain; or ravines, mulch, fill,
organic debris (later rots and settles).
Over window/door, straight or diagonal - loading/header defect - may appear as horizontal along top or bottom of header, vertical at ends of header
(possibly due to differences in thermal expansion of different materials of header vs. wall) or vertical/diagonal at center of header (loading failure)
or at corners (possible point-load failure)
Cracks in a poured concrete foundation which are diagonal or vertical and which are generally uniform in width, or which taper to an irregular hairline
form, usually in fact a discontinuous crack in the hairline area, are usually shrinkage cracks and should not be ongoing nor of
structural significance, though they may invite water entry through the wall.
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
Critique, contributions wanted: Contact Us to suggest corrections or additions to articles at this website, and if you wish, to receive online listing and credit as a contributor. Particular thanks are due to the many experts and also consumers who read and critique technical articles at InspectAPedia.com.
Additional technical contributors & reference sources for this article are listed below.
Use links just below or 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.
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, 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
Technical Edits, Changes, Amendments to This Document
06/07/2007 adding text, illustrations, content
9/23/2006 editing to clarify text and add content; Technical review (partial) by Arlene Puentes.
4/17/2006 editing to clarify text in several sections.
Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
Our recommended books about building & mechanical systems design, inspection, problem diagnosis, and repair, and about indoor environment and IAQ testing, diagnosis, and cleanup are at the InspectAPedia Bookstore. Also see our Book Reviews - InspectAPedia.
The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 2010, $69.00 U.S., is available from Carson Dunlop, and from the InspectAPedia bookstore. The 2010 edition of the Home Reference Book is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. InspectAPedia.com ® author/editor Daniel Friedman is a contributing author. Field inspection worksheets are included at the back of the volume.
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.
Design of Wood Structures - ASD, Donald E. Breyer, Kenneth Fridley, Kelly Cobeen, David Pollock, McGraw Hill, 2003, ISBN-10: 0071379320, ISBN-13: 978-0071379328 This book is an update of a long-established text dating from at least 1988 (DJF); Quoting: This book is gives a good grasp of seismic design for wood structures. Many of the examples especially near the end are good practice for the California PE Special Seismic Exam design questions. It gives a good grasp of how seismic forces move through a building and how to calculate those forces at various locations.THE CLASSIC TEXT ON WOOD DESIGN UPDATED TO INCLUDE THE LATEST CODES AND DATA. Reflects the most recent provisions of the 2003 International Building Code and 2001 National Design Specification for Wood Construction. Continuing the sterling standard set by earlier editions, this indispensable reference clearly explains the best wood design techniques for the safe handling of gravity and lateral loads. Carefully revised and updated to include the new 2003 International Building Code, ASCE 7-02 Minimum Design Loads for Buildings and Other Structures, the 2001 National Design Specification for Wood Construction, and the most recent Allowable Stress Design.
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.
"Avoiding Foundation Failures," Robert Marshall, Journal of Light Construction, July, 1996 (Highly recommend this article-DF)
"A Foundation for Unstable Soils," Harris Hyman, P.E., Journal of Light Construction, May 1995
"Backfilling Basics," Buck Bartley, Journal of Light Construction, October 1994
"Inspecting Block Foundations," Donald V. Cohen, P.E., ASHI Reporter, December 1998. This article in turn cites the Fine Homebuilding article noted below.
"When Block Foundations go Bad," Fine Homebuilding, June/July 1998
Straw Bale Home Design, U.S. Department of Energy provides information on strawbale home construction - original source at http://www.energysavers.gov/your_home/designing_remodeling/index.cfm/mytopic=10350
More Straw Bale Building: A Complete Guide to Designing and Building with Straw (Mother Earth News Wiser Living Series), Chris Magwood, Peter Mack, New Society Publishers (February 1, 2005), ISBN-10: 0865715181 ISBN-13: 978-0865715189 - Quoting: Straw bale houses are easy to build, affordable, super energy efficient, environmentally friendly, attractive, and can be designed to match the builder’s personal space needs, esthetics and budget. Despite mushrooming interest in the technique, however, most straw bale books focus on “selling” the dream of straw bale building, but don’t adequately address the most critical issues faced by bale house builders. Moreover, since many developments in this field are recent, few books are completely up to date with the latest techniques. More Straw Bale Building is designed to fill this gap. A completely rewritten edition of the 20,000-copy best--selling original, it leads the potential builder through the entire process of building a bale structure, tackling all the practical issues: finding and choosing bales; developing sound building plans; roofing; electrical, plumbing, and heating systems; building code compliance; and special concerns for builders in northern climates.
Mobile View
