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Photograph of a bowed concrete block foundation wall, probably from frost cracking. Drop a plumb line to measure total inwards bulging of this block foundation wall.How to Distiguish Foundation Bulging vs. Leaning

  • BULGED vs. LEANING FOUNDATIONS - CONTENTS: 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
  • POST a QUESTION or READ FAQs about the difference between foundation bulging & foundation leaning: different causes, effects, risks, & repairs
  • REFERENCES
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Foundation damage evaluation:

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.

This article series 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.



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

Photograph of a leaning foundation wall

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.

[Click to enlarge any image]

Watch out: 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.

The same forces produce different effects on poured concrete walls compared with masonry block, brick, or stone walls

Photograph of a bulging foundation wall (C) Daniel FriedmanEven 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. Below the photo shows a catastrophe in the making: earth loading exacerbated by wet soils has been pushing in this foundation wall for many years.

The wall is bulged and cracked, mostly horizontally. An owner built a second interior wall (at right in the photo) to try to serve as a source of bracing for the outer foundation wall (at left in the photo) and installed a forest of diagnoal and horizontal bracing between the two. This heroic effort was made in futile hope to avoid what was actually needed:

So which foundation materials are more likely to bow or bend versus lean or shift?

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.

Photograph of a leaning foundation wall (C) Daniel FriedmanIn 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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Continue reading at FOUNDATION BULGE or LEAN MEASUREMENTS or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.

Or see BULGED FOUNDATION REPAIR METHODS for a discussion of the diagnosis of specific crack patterns in masonry

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