How to Distiguish Foundation Bulging vs. Leaning InspectAPedia® -
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
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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.
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.
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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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.
"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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