Vertical foundation movement: this article gives details about how to evaluate & diagnose the cause of vertical foundation movement and the foundation settlement or other cracks that are observed. We discuss settlement cracks, leaning or tipping foundation walls, vertical or "up and down" shifts or heaves in foundation walls and footings and related problems.
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Vertical foundation movement may be foundation settlement, frost heaves, movement caused by expansive clay soils, footing settlement, or severe damage from earthquakes or other more sudden forces. Diagnosing the type of foundation movement and its cause are essential in deciding on the appropriate measures to repair a damaged foundation wall and to prevent future foundation damage.
Leaning buildings: Our photo, courtesy of Tom Smith, shows the Leaning Tower of Pisa - whose foundation has moved both laterally and vertically as the structure began tipping even during construction.
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.
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 always adding to this document. Contact us with questions or suggestions.
Vertical movement in foundations, in the most general cases, is caused by downwards movement of the wall or wall footings such as when a wall footing sinks in soft soil, or by an up and down movement of the wall or wall footings such as when a wall is disturbed by frost in a freezing climate or by expansive clay soils which expand or shrink as their water content increases or decreases.
Vertical foundation or slab movement is typically caused by the following conditions or events:
Foundation walls or building piers can be lifted vertically by frost heaving, by frost lensing, as well as bulged or pushed inwards by horizontal pressure from frozen soils. See BUCKLED FOUNDATIONS due to INSULATION? for additional details about these phenomena.
Here are some classes of vertical foundation or building wall movement which we illustrate and discuss in more detail below
A Common Source of Vertical Frost Heave - Un-heated Homes
In northern climates an inspector may encounter a concrete slab basement floor which is remarkably broken up from frost heaves. In the Northeastern U.S. early in the 20th century it was common to route building downspouts carrying roof runoff into drains that passed under the basement or crawl space slab and into the sewer system.
When such houses are left un-heated (a likely condition in a period of high heating costs and slow real estate sales market), temperatures can drop sufficiently to cause heaving of the foundation or more commonly the basement floor slab.
If you see a floor which has broken in a rather straight line you might suspect that a stopped drain line under the floor or a broken drain line under the floor added water in that location, causing the more severe frost damage following the line of the buried pipe or drain. drawing courtesy Carson Dunlop Associates.
We discuss frost damage to unheated homes further at Winterize- Heat Off Procedure and at Frost Heave/Expansive Soil Cracks in Slabs we list things to check to predict the chances of frost heave damage to a home where heat is going to be left turned off.
Frost and soil pressure can also cause horizontal movement of the building foundation or piers, as we discuss further at HORIZONTAL MOVEMENT IN FOUNDATIONS.
Non-Uniform Building Settlement - Leaning or Tipping Buildings
Other Building Movement Causes & Cracks
Differential settlement in a foundation or wall:: We use the term "differential settlement" to describe a condition in which one portion of a building foundation is moving down, (or up and down) at a different rate or in a different amount from other portions of the foundation or wall.
Differential settlement will damage the foundation or wall by producing (usually vertical, possibly diagonal or stair stepped) cracks and other symptoms of wall movement.
The large foundation crack in this poured concrete wall was caused by differential settlement in a new foundation wall. All of this movement occurred during the first 13 months after the home was built.
Differential settlement in a building slab or supporting piers can produce significant and recurrent cracks in the living area as drywall and trim are torn and dislocated during building movement.
This photograph shows a significant crack in an upper floor interior wall which was bending as the center of this home settled downwards. The home had been built over the site of a previous stream bed.
Its basement floor slab and supporting piers was settling downwards at its center. There was some additional movement in some of the building perimeter foundation walls, but the most significant settlement was at the center of the basement floor.
Uniform settlement in a foundation or wall: Some buildings may settle so uniformly that the entire building moves down without producing cracking in the building's foundation or walls.
For example, while it has a few settlement cracks, the Empress Hotel in Victoria BC, a very large masonry structure built on pilings on what was originally a marsh, has settled rather uniformly down over many decades, so that now visitors enter the hotel's "lobby" on what was originally its second floor.
Vertical movement between different sections of a masonry foundation wall, whether it is constructed of concrete, concrete block, brick, or stone, tends to produce vertical cracks or a combination of vertical and step cracks through the wall, though there are definitely exceptions to this rule, as we will point out.
Other vertical or near vertical cracks in poured concrete can occur in a masonry block or concrete or brick or stone foundation wall without leaning or bulging if the entire wall is moving due to footing settlement or frost.
In this photograph notice that the cracking is occurring at a building corner, probably at a garage door.
The footings at garages are often not buried as deeply as other portions of a home (which has a basement much deeper below grade).
There is greater risk that the builder didn't get the garage footers below the frost line or that in addition, the un-heated garage is more vulnerable to frost damage (only in freezing climates of course).
We like to look at variations in the width of a vertical crack to try to understand further what's happening to the foundation wall. In general we pose that if a crack is wider at its top than its bottom, differential settlement may be allowing one section of the wall to slope downwards away from its neighbor.
Or in less common cases, for example a footing which was placed mostly on soft fill but which passes over a boulder, might break over the boulder and slope downwards on both sides of the boulder, producing a crack wider at its top than its bottom.
If a vertical crack is fairly uniform in width we pose that it was produced either by a non-sloping vertical settlement of one section of the footing or foundation wall, or the crack was produced by shrinkage (in some wall materials like concrete) not by vertical movement at all.
But unfortunately this "rule" has exceptions. When a masonry wall is "shrinking" such as curing concrete (and some experts pose also drying concrete block), it is not held uniformly in place across its length.
The top of a poured concrete wall is generally unrestrained during the first portion of it's initial 28 days of curing, since nothing has been built atop the wall, or even if someone has started floor framing, the floor framing system does not secure the top of the wall against shrinkage movement.
On the other hand, the bottom of the wall is pinned (or should be) to its previously poured and cured footing. The bottom of the newly poured concrete wall is more secured against horizontal moment along its length than its top.
This might therefore produce some vertical shrinkage cracks that are wider at top than bottom. Why don't we always see this in concrete walls? As a concrete wall shrinks, the stresses produced in the wall are not concentrated at one single point, say the center of the wall; rather, shrinkage cracks may appear in various locations in the wall, not just at its center. Shrinkage cracks may be distributed rather than concentrated. However shrinkage cracks do tend to appear at local stress points in a wall such as at discontinuities in its form caused by windows, doors, or holes left for mechanicals and pipes.
We discuss the types of crack or movement patterns produced by shrinkage, expansion, and settlement further at SHRINKAGE vs EXPANSION vs SETTLEMENT.
Concrete walls tend to display vertical cracks but settlement or frost heaving at a corner of a concrete wall can produce diagonal cracks or breaks in that location.
Steep diagonal cracks may also appear in concrete foundations due to unusual point loads that exceed the compressive strength of the concrete (maybe it was weak concrete not high loading), and we've seen steep diagonal cracks in poured concrete and other high-rise masonry buildings exposed to frost damage.
Steep diagonal shrinkage cracks: But in this photograph of a diagonal crack in a poured concrete foundation, we are almost certainly looking at a large shrinkage crack. Notice that discontinuity in the crack pattern?
Details about diagonal foundation cracks: cause, diagnosis, repair, are found at DIAGONAL FOUNDATION CRACKS.
Vertical movement in a concrete block or brick wall might appear as either vertical cracks but more often as step cracks in which the crack pattern follows the mortar joints between the masonry units in a stair stepping pattern.
In this photograph, major vertical dislocation, foundation settlement, has caused large step-cracking in the concrete block foundation wall. In addition to diagnosing and correcting the reason for this settlement or foundation movement, this section of wall will probably have to be rebuilt.
Where step cracks are present, if you draw an imaginary line at right angles (orthogonal) to the diagonal formed by the stair stepped cracking, the downwards direction of the line will generally point to the center of the point of downwards (or up and down) movement in the structure.
But unfortunately even this "rule" has exceptions. In Florida we observed a concrete block home with step cracking high in some of its walls. The cracks were traced to settlement at the other end of the building which was responding to soil subsidence over a sinkhole.
Details about diagonal foundation cracks: cause, diagnosis, repair, are found at DIAGONAL FOUNDATION CRACKS.
Reader Question: Pier or Pile Foundation settlement, movement, diagnosis & repair suggestions for a New Mexico home built on fill and clay soils
House dirt pad was built up on original earth and 13 cement pillars were poured along the raised portion of earth. The house is 33' X 83'. Just recently the entire north portion of the house (83') has developed a crack along the tile floor and plaster wall.
The most noticeable part of this 'shift' seems to be more toward the end of the house that sits on the pillared foundation.
The bathroom wall is about half way along this wall and the sewer line sits under this portion of the house. There is a subtle but noticeable odor in this area and the tile has separated from the wall about 1''.
What is happening and how do I fix it? The doors and windows are not opening smoothly and the wall appears to be cracking at an alarming rate. I have homeowners insurance. Thanks, - L.C.
Sketch at above left provided courtesy of Carson Dunlop Associates.
Reply: foundation diagnosis and repair suggestions for settling piers
This question along with a more detailed answer is discussed at PIER FOUNDATION PROBLEMS. A competent onsite inspection by an expert usually finds additional clues that help accurately diagnose a problem. That said, here are some things to consider:
I'd be a fool to pretend to diagnose building cracks by email, not to mention sight unseen.
For more guidance on evaluating the seriousness of foundation cracks & movement see
Continue reading at VERTICAL FOUNDATION MOVEMENT REPAIRS or select a topic from the More Reading links or topic ARTICLE INDEX shown below.
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Frequently Asked Questions (FAQs)
Question: how much out of level can a foundation be - allowable tolerances during construction?
What is the acceptable differential/gradient for tolerances permitted during the initial foundation construction? I have heard that it is 2%, or 1" total differential over the span of about 20ft, but that statement had no real backing. - Kyle Olsen 8/5/11
Final authority on the requirement for level footings and foundations rests with your local building code official, but there are various building code guidelines.
2. FOOTING AND FOUNDATION DESIGN. Section R401 - R404 IRC 2009
Footings and foundations shall be designed and constructed in accordance with Sections R401 through R404.14.11. Footings and foundations shall be built on undisturbed soil or engineered fill. The top surface of footings shall be level. The bottom surface of footings are permitted to have a slope not exceeding 1 unit vertical in 10 units horizontal (10-percent slope). Footings shall be stepped where it is necessary to change the elevation of the top surface of the footing or where the surface of the ground slopes more than 1 unit vertical in 10 units horizontal (10-percent slope).
Question: what causes vertical cracks
i need information about vertical cracks how its happened ? how many type it have ? how we fix ? for my project can you help me sir ? - Ibrahim 5/4/12
Ibrahim, for a general understanding of how to recognize vertical foundation cracking and its common causes, start reading at VERTICAL MOVEMENT IN FOUNDATIONS. If you are asking for assistance with problems needing attention in your own home you will need an expert on-site to inspect, evaluate, and propose repairs. Typically you can find such help from an experienced foundation repair contractor, or if there is a more complex problem that requires foundation or foundation repair design work, you'll want to discuss the case with a professional engineer whose area of expertise and experience include residential foundations.
Question: house settled after a flood - damage not covered by insurance
We had no settling until after a flood swept through our property. The flood completely covered our land and invaded one room of our home that is lower than the rest of the house.
The structure was completely surrounded by lots of water and it went under the house into the crawl space as well. Immediately afterwards, the house began to sink and settle causing foundational and cosmetic cracks. Our living room floor has dropped a full inch below the chimney hearth. Both our home owners insurance and our flood insurance says the damage isn't covered by those policies.
We contend that the settling is a direct result of the flood water going under our home and permeating the ground making it too soft to maintain the structure of the home. Is this possible? What could be our possible course of actions? Thank you for any help you can provide. - Jill 7/5/12
Jill, an experienced professional can usually find evidence that explains the age and causation of foundation movement or damage. In the case you describe it sounds to me as if you'd want to hire a professional engineer whose area of expertise and experience are in foundation design, diagnosis, and repair. Typically a structural engineer or a civil engineer has the appropriate training but you might want to confirm that your professional also has experience with residential foundations. A detailed inspection and report by an expert with proper credentials should be a compelling argument to discuss with your insurance company.
Question: Professional Engineer Comments on Qualifications
There is no such thing as a licensed structural engineer that is "not familiar" with foundation design and/or residential construction. A licensed structural engineer, "P.E.", would determine the most cost effective and durable solution.
Well put, Dave P.E. and we agree with you and your advice except for the following warning:
Watch out: there are some licensed professional engineers who violate their licensing state's guidelines by practicing out of their area of training.
For example we have an unemployed aerospace engineer in one city who became a "home inspector" and who admitted publicly that for years "at the beginning I made plenty of mistakes", and we have an electrical engineer trained in circuit design in a second city both of whom perform what they advertise as "engineering inspections" of homes, offering diagnostic and remedial advice for structural problems.
Questions & answers or comments about diagnosing and repairing foundation settlement, movement, cracking in continuous wall foundations and footings or in individual posts, columns, or supporting piers.
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