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Foundation cracks leading to collapse (C) Daniel FriedmanHow to Inspect Foundations for Structural & Other Defects

  • FOUNDATION INSPECTION METHODS - CONTENTS: How to Perform Visual Diagnostic Inspection of a Foundation Wall or Slab. Types of foundation damage. Extent of foundation damage. Photographs of foundation crack patterns. Four contractors, four opinions, how do I decide whom to believe? . Advice on choosing a foundation engineer, contractor, or expert to diagnose and repair problems
  • POST a QUESTION or READ FAQs about methods for inspecting foundations for cracks, damage, leaning, bulging, bowing: damage evaluation & repair procedures
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This document provides inspection methods useful in recognition & diagnosis of 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.



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Building Foundation Inspection Methods: How to Evaluate Foundation Damage

The general procedural steps and major topics in a foundation inspection include these steps. Links to discussions of each of these topics are at the left side of this page.

The photo at the top of this page shows a badly-cracked masonry block foundation wall with severe bulging and dislocation - this wall needs to be rebuilt and the cause of this movement corrected before the wall collapses. At this website we explain how it is sometimes possible to be confident about the cause of foundation damage which in turn helps assess the risk presented to the building.

CONTACT us if you have questions, suggestions, or content contributions for this material. We are pleased to give full citation credit for technical reviewers and content contributions.

Factors to Consider When Evaluating Foundation Damage

Below we list the broad categories of topics that a foundation inspector may need to consider when inspecting and evaluating the condition of a building foundation.

  1. Site Factors: Observe site factors affecting the structure such as slope, drainage, rock, or nearby activities such as blasting.
    See SITE FACTORS AFFECTING FOUNDATIONS.
  2. Construction type, materials: Identify construction type, materials, sequence of construction - the history of the site, the foundation, and its construction details.
    See FOUNDATION CONSTRUCTION TYPES.
  3. Foundation Defects of Occurrence: Observe defects of occurrence - things that have happened to the structure such as signs of movement, history, other clues. A foundation crack, foundation movement, foundation lean or foundation bulge, or foundation damage due to impact, frost, or point loads are all defects of occurrence. Damage that occurs to foundations is organized according to several viewpoints. See these major topics, each of which you'll see is subdivided into more detail:
    1. FOUNDATION FAILURES by TYPE & MATERIAL
    2. FOUNDATION FAILURES by MOVEMENT TYPE
    3. FLOOD DAMAGE TO FOUNDATIONS
    4. FOUNDATION CRACK DICTIONARY
    5. CONCRETE SLAB CRACK EVALUATION
  4. Foundation Defects of Omission: Observe defects of omission - things that have been left-out or removed (harder to spot) such as possible absence of supporting posts, piers, footings, or other critical components. Defects of omission are not an event that happened to a foundation, but rather things that were forgotten or removed, such as omitting footings or removing a supporting Lally column in a building.
    See FOUNDATION DEFECTS OF OMISSION.
  5. Evaluate Foundation Observations: Evaluate the information which has been collected (history, observations, clues), visual evidence of their impact on the structure, and their importance. Any building inspector, building contractor, masonry repair contractor, or carpenter needs to be able to recognize when additional expert evaluation or repair is needed by a foundation or structural engineer or foundation repair specialist.

    All of these people are called-on to make first-level inspections and to form opinions about all sorts of building components. Often very simple non-engineering analysis can be helpful or even essential in deciding when more expert help is needed. Examples include simply making a measurement to establish that a foundation wall has moved or is leaning. See
    1. FOUNDATION CRACK DICTIONARY
    2. FOUNDATION BULGE or LEAN MEASUREMENTS
    3. FOUNDATION DAMAGE SEVERITY
    4. FOUNDATION MOVEMENT ACTIVE vs. STATIC
    5. CONCRETE SLAB CRACK EVALUATION
  6. Report Observations & Make Foundation Repair Recommendations: Communicate the observations and recommendations to the client with clarity so that the client understands the implications of the findings and the need for action (if any).
    See FOUNDATION DAMAGE REPORTS
  7. Repair the Damaged Foundation: depending on the condition of the foundation system, repairs may be needed, and in emergency cases such as the threat of imminent collapse, other measures such as installation of temporary foundation support, or even evacuating an unsafe structure and keeping people away from it could be in order. An example is the discovery of a bulged structural brick wall - a condition that can cause sudden catastrophic building collapse.

    See FOUNDATION REPAIR METHODS

4 Different Contractors, 4 Different Opinions about Foundation Cracks: Who's Correct?

Question: I've now asked four foundation contractors and gotten very different opinions

I'm going a little nuts here about this foundation crack and would love some guidance. When I bought my 100 year old home in Brooklyn a year ago, the basement side-wall right near the front of the house had a diagonal crack from a window to the corner. it's about 4 feet and starts a little wider and gets smaller. This sidewall is on the detached side of the house.

A few weeks ago, I noticed a new, very thin horizontal crack. After researching it, I realized it goes almost the full length of the house. It wavers up and down a little, but is mostly a little above grade and near the middle of the wall. Next to this wall is an unused driveway (it's actually too small for a car...so it really hasn't been used).

I've now seen 4 contractors and gotten very different opinions.

Modesto (20 years experience in masonry -- though not foundation cracks) says not to worry. it's not serious.

Quality First, which specializes in foundation repair, says it's due to outward pressure from the soil under the driveway pushing horizontally against my basement wall and that eventually the wall could bow. They recommend a 5k fix including epoxy and carbon straps. The guy seemed very knowledgeable, had a great sales pitch and tons of materials and references.

Two other contractors suggest the cracks might be due to moisture and suggest taking out the broken areas, re pouring concrete and adding some steel in the area with the "more serious" diagonal crack. Neither specialize in foundation work., but both were experienced.

I'm kinda at my wits end with time and money and appreciate any advice .... Best, - BL

Reply: We need to know the type of foundation movement, its cause, and its impact on structure to decide on urgency and type of foundation repair

A competent onsite inspection by an expert who is familiar with the causes and cures of foundation damage usually finds additional clues that help accurately diagnose a problem beyond what would occur to a homeowner to describe in email. Put another way, we cannot reliably diagnose the cause, nor evaluate the significance of a crack by email text description, though knowing the type of foundation material, site characteristics, drainage issues, and seeing some photos, measurements, and building history would help. That said, here are some things to consider:

Typically diagonal foundation cracks are from settlement or on occasion frost heave at a building corner. On occasion, lensing - frost sticks to and lifts a foundation. In extreme cases of horizontal foundation movement, diagonal cracks may of course appear at building corners, especially in block or brick foundation walls.

Horizontal cracks in foundations are typically from frost pressure, earth pressure, or other loading against the foundation wall. The height of the crack in your description, as it's closer to the top of soil, suggests it may be due to frost pressure on the wall (check roof drainage at that wall - notice if the wall is below a roof eaves (likely) or at the gable end of the home (no roof spillage, less likely).

Old Foundation racks Can "Suddenly" Appear in Our Consciousness

f course it's possible that that horizontal crack has always been there, caused by earth loading by heavy equipment that drove close to the foundation wall during the time that the driveway was constructed. Often a crack in a foundation is present for years but goes unnoticed until something gets people worried. Then it suddenly "appears". A careful inspection of the interior of a a crack can often tell us if it's new or old.

The urgency of foundation repair depends on several factors such as

  1. The total amount of foundation movement that has occurred
  2. The rate of of foundation movement
  3. The impact of foundation movement on the structure - water entry, or loss of structural stability.
  4. The cause(s) of foundation movement

First Identify Severe or Dangerous Foundation Damage - collapse risk

Watch out: As we introduce at our home page for this topic, FOUNDATION CRACKS & DAMAGE GUIDE, since certain masonry structure defects, such as even slightly-bulged structural brick masonry walls (above or below ground level) or severely bulged below-ground masonry block or stone foundations, can lead to sudden precipitous and catastrophic building collapse, dangerous conditions may be present at some properties. While there are often hidden conditions which can disguise building conditions, the ability to recognize those potentially urgent or dangerous conditions which can be detected is important in a foundation inspection.

Get the Details that Support the Contractor's Opinion

Watch out also and avoid or at least defer non-urgent repairs that may be unnecessarily costly in comparison with the impact of the crack on the structure or that fail to first identify and understand the cause of the foundation cracking and second to evaluate and understand its impact on the structure.

Some fellows who work in construction are very experienced, knowledgeable, and honest, but they were not English majors in school. You have to ask to hear more of the contractor's reasoning before you'll be comfortable with an answer like "Nah, don't worry about it!" much less "Yeaaah, this is a big problem and needs a big expensive repair."

Make a Thorough and Technically Accurate Foundation Inspection

In addition to the outline of how we approach foundation inspection found of this topic found at the top of this article, you might want to see these references:

  1. FOUNDATION CRACK DICTIONARY - how do we evaluate and diagnose the type of crack in a foundation
  2. FOUNDATION BULGE or LEAN MEASUREMENTS - how do I measure the amount of foundation movement that has occurred
  3. FOUNDATION DAMAGE SEVERITY - how bad is the foundation crack? how urgent is repair
  4. FOUNDATION MOVEMENT ACTIVE vs. STATIC - is the foundation crack a sign of ongoing movement?

Choose a Qualified Foundation Expert

For costly or potentially dangerous foundation damage, be sure that your "expert" really is one.

A civil engineer or structural engineer who is specifically experienced in building foundation diagnosis and repair can give reliable and often economical advice on what foundation repair is needed. So can some experienced foundation repair contractors.

Watch out for "foundation experts" who don't know foundations: OPINION-DF: even licensed professional engineers or architects who do not have specific experience and training in building foundations. Those experts can often design a repair that will be "safe" and "work" but we have found that some who are not familiar with foundations are not aware of repair products and procedures specifically designed for these problems.

The result can be "overkill" or a foundation repair design that was more complex, more disruptive, and more expensive than necessary.

At Vertical Foundation Movement Repairs we mention a case where just this problem occurred at a home built over a landfill.\

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Continue reading at FOUNDATION INSPECTION STANDARDS or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.

Or see FOUNDATION INSPECTION DAMAGE REPORT GUIDE

Or see FOUNDATION CONTRACTORS, ENGINEERS for advice on how to choose an expert to diagnose or repair a building foundation problem.

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FOUNDATION INSPECTION METHODS at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

INDEX to RELATED ARTICLES: ARTICLE INDEX to BUILDING STRUCTURES

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