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How to measure the severity of foundation wall bulging or leaning:
This article series explains a simple procedure using string and a measuring tape to measure the amount of leaning, bowing, or bulging in a cracked,
bulged, or tipped building foundation wall or in any other building wall or vertical surface.
This is chapter of "How to Evaluate Foundation Cracks" which is part of "the Foundation Crack Bible" website.
This document 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.
Medir a quantidade de magra ou protuberância em uma parede
We also provide a MASTER INDEX to this topic, or you can try the page top or bottom SEARCH BOX as a quick way to find information you need.
How to measure the amount of lean or bulge in a foundation wall - a simple, easy procedure to tell just how much foundation movement has occurred
The photo at the top of this page shows a bulged masonry foundation wall which has also been cut and interrupted to make a doorway.
The measuring tape set vertically against the wall can show that the wall is not straight (the tape is straight) but this is not the best way to measure the amount of bulge or lean in a foundation wall, because without a plumb line we don't know that
our tape is perfectly vertical. In detail below we describe the proper way to measure foundation movement.
Measuring foundation wall tip, lean, or bulge: is simple: drop a plumb line near the most-bulged area (usually the center) of the wall, perhaps fastening it to
a nail in a floor joist overhead, about 4" in from the wall. Measure from the string in to the wall at various heights up the wall.
You'll be able
to easily pinpoint the height of the most bulge or lean. This is not engineering. It's simple a simple mason's method to measure a wall or chimney during
construction to keep it plumb.
You may need to hire the services of a licensed professional engineer, [make certain that your engineer
is experienced with foundation troubleshooting and repair], especially if there is need to design a special building
repair method or if there is apparent risk of possible building instability or collapse.
Wall most-bulged in near the outdoor ground surface (commonly occurs in the upper 1/2 of the wall), perhaps at a depth equal to the frost line
in climates where freezing occurs or in the top 1/3 of the wall if we suspect water or frost loading on the wall, or possibly vehicle traffic driving too
close to the wall.
Wall most-bulged in at its center height - the center of the overall height of the wall (common) - we suspect vehicle traffic or possibly water/earth loading
Wall most-bulged in near its bottom (unusual) - we suspect earth loading or wet earth loading.
Here are the details of how to measure foundation movement, what you need, how to make measurements
A plumb line, is simply a string suspended by a weight, so as to give a perfectly vertical line from which to measure back to the wall surface.
We drive a nail into the side of a floor joist or into the sub floor overhead, in the ceiling over the room where we're working, typically a basement
or crawl space.
We guess by observation which portion of the foundation wall has leaned or bulged the most, and we put our nail (to suspend the string)
in front of and less than a foot away from that part of the wall. (See our illustration above.)
Quiesce the plumb line, that is, make sure that it has stopped swinging or moving, before making your measurements of the foundation movement.
A tape measure or yardstick or ruler is used to measure the distance from the face of the wall to the closest surface of the vertical
plumb line. We measure at multiple locations from the floor up to the top of the wall, writing them down in order and perhaps even making
a pencil number on the wall too, so that we can identify just which part of the wall is pushed inwards or leans over the most.
We subtract the individual measurement amounts from our "home base" starting measurement, at a point on the wall where there has been
zero movement, usually at the very bottom of the wall.
We don't care about the absolute value of the various measurements, we care about the difference between these measurements.
Our base reference point for comparing measurements is normally the bottom of the wall.
Usually the very bottom of a building wall will not have moved inwards, particularly if a concrete floor has been poured against the foundation.
The entire building floor slab is acting as an "anchor" to hold the bottom of the foundation wall in place. So we take the distance between
the foundation wall and the string at the bottom of the wall as our "home base" or point of assumed "zero movement".
We compare this
measured value with the other measurements between the wall and the string. If the foundation wall or any part of it higher than the level of
the floor has moved, tipped, or bulged inwards, those measurements from wall-to-string will be less than the distance, wall-to-string
measured just above the floor level. That's because the wall has moved inwards, towards the string.
We compare our measurements to recommended standards of amounts of wall movement in order to form a general opinion about
whether expert analysis or repair are probably needed. We have found no nationally accepted standard or opinion for just what these
numbers need to be, probably because some judgment is needed about particular site conditions.
For example, a small amount of movement
that is new, in an old foundation wall that had not previously moved, might be significant. See some collected opinions about "how much foundation movement is a worry" at FOUNDATION DAMAGE SEVERITY
Here is an actual example of measuring the amount of foundation wall bulge inwards
We "eyeball" the "bulged" foundation wall and guess at the point at which it is bulged inwards the most - perhaps close to the center of the
length of the wall (right-to-left dimension)
We hang our string or plumb line from the nearest floor joist, keeping the string a few inches away from the foundation wall
We measure 4.00 inches between the foundation wall surface to our vertical plumb-line string at 1" above the concrete floor - this is our "zero point" or "home base" measurement
We measure 2.00 inches from the same foundation wall surface to our vertical string at a height of 5' from the floor
We measure 3.25 inches from the same foundation wall surface to our vertical string at the very top of the wall just under the sill plate.
We check that we've measured at the area of greatest inward bulge in the wall by moving our plumb line to our left, then to our right
on either side of the ceiling joist we used to hang the string for our first measurement. If the distances we measure, wall to string, are
greater than the distances we measured at our first trial, then that one is the point of greatest inwards foundation wall bulge.
Finally we do the math: subtract our "higher on wall" and "closer to string" measurements from our "at the floor" and "farthest from string"
We see these results in foundation bulge measurements:
Foundation Wall Bulge-in at floor = 0 inches
Foundation Wall Bulge-in at 5'up from floor = 4" - 2" = 2" of inwards bulge
Foundation Wall Bulge-in at the top of the wall = 4" - 3.25" = .75" of inwards lean
How to distinguish between a "bulged" foundation wall and a "leaning" foundation wall, and why we care
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. 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.
damage which shifts a building off of its foundation can also produce something that looks like and can be mistaken for
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.
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.
Different Causes of Leaning, Bulging, Cracking of Foundation or Masonry Walls May Produce Different Effects
Horizontal foundation wall movement, creep, non-leaning lateral shift
On less frequent occasions we've found that an entire masonry block wall (or portions of it) were pushed horizontally
inwards by some outside force, without causing the wall to lean or bulge. In the photograph here we suspect that the
cracks in this masonry block wall occurred as a defective wall footing began to creep down a steep hill
behind the building.
In a pure example of horizontal creep or movement without leaning in a masonry wall or foundation, all of the
differential movement measured (wall to string) between the wall bottom point (held in place by the floor slab) and
the inwards-pushed wall section, will be a horizontal movement of that portion of the wall, and if it's masonry block,
you'll see that the inwards-moved blocks are "hanging over" or projecting past the surface of the masonry blocks that did not move.
Other vertical cracks 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.
Watch out: Beware of this condition: if the bottom of a wall is not pinned in place by a secure footing or a concrete slab, the entire wall, from top
to bottom may move horizontally with no leaning and with no "overhang" of one portion of the wall over another.
In this case
we'd expect to see cracking or evidence of separation of this section of wall from its neighboring sides - as you can see in the
upper vertical cracking at the left side of the masonry block wall in the photograph above. (This wall may also be leaning slightly.)
Example of impact damage to foundation walls
Impact damage from a vehicle or from unusual weather such as a hurricane which lifts and tosses large objects, can
lead to severe foundation or masonry wall damage and may even render the wall unstable and unsafe. In the photograph shown
here the cause of damage to the foundation wall is pretty obvious.
Almost certainly a delivery truck has backed into
this concrete block wall, perhaps even more than once. The damage to this wall was extensive, extending nearly
to the top of the structure. The wall needs extensive repairs, probably reconstruction.
Combinations of foundation wall movement
Wall bulge + step cracking
Step cracks may also be present in bulged, leaning, or horizontally pushed foundation walls if they were constructed
of brick or masonry block, or possibly (though less common) of stone.
In fact since the building foundation corners are stronger
than the center portions of the foundation wall (the opposing wall at right angle resists movement of the wall being pushed),
wall bulges, leans, and cracks tend to occur towards the center of the wall, resulting in step-cracking closer to
the ends of the same wall.
In the photograph above, frost push has bulged the center of the foundation wall inwards; as the forces of wet earth
and or frost pushing on the upper 1/3 of this foundation wall were applied at the center of the wall, the wall bulged
inwards and cracked horizontally at the point of most pressure.
As the same forces causing this wall to bend were exerted
closer to the building corners, the wall cracked in the step-crack pattern clearly marked in this picture by the "repairs"
which have been done by filling the cracked joints.
If the total amount of wall movement was minor and if the outside
source of pressure (water and frost) has been corrected, further repair or reinforcement may not be needed.
Horizontal wall movement and masonry block "overhang"
Inspectors or building owners may also encounter a foundation wall which has moved inwards in a combination of forms, both bulging at its most-pushed-in
point (with horizontal cracks in the foundation wall) and the wall may have also been pushed inwards sliding some of
the masonry blocks inwards past others which have remained in place.
In this case you'll see both that some masonry wall
blocks will overhang or protrude past others in the wall (usually upper inwards pushed blocks hang over lower more stable
blocks closer to the floor), and there may be bulging and cracking at another elevation of the wall.
This is a photograph of frost push and horizontal overhang or sliding between horizontal courses of a masonry block wall.
Examples of other step cracks occurring in masonry walls or masonry foundations
Other step cracks will of course also occur in building masonry block foundation walls and in
brick masonry walls that are not leaning
or bulging particularly, where frost or settlement have been causing an "up and down" movement in the foundation or footing.
We will also encounter step cracks where earth pressure or frost have pushed such a wall horizontally, breaking the
masonry courses near a corner or wall-end in a stair-step pattern such as we see in this little example of water and frost
damage to a brick retaining wall.
Continue reading at BULGED FOUNDATION REPAIR METHODS or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.
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
Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
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.
Carson, Dunlop & Associates Ltd., 120 Carlton Street Suite 407, Toronto ON M5A 4K2. Tel: (416) 964-9415 1-800-268-7070 Email: email@example.com. The firm provides professional home inspection services & home inspection education & publications. Alan Carson is a past president of ASHI, the American Society of Home Inspectors. Thanks to Alan Carson and Bob Dunlop, for permission for InspectAPedia to use text excerpts from The Home Reference Book & illustrations from The Illustrated Home. Carson Dunlop Associates' provides extensive home inspection education and report writing material.
The Illustrated Home illustrates construction details and building components, a reference for owners & inspectors. Special Offer: For a 5% discount on any number of copies of the Illustrated Home purchased as a single order Enter INSPECTAILL in the order payment page "Promo/Redemption" space.
TECHNICAL REFERENCE GUIDE to manufacturer's model and serial number information for heating and cooling equipment, useful for determining the age of heating boilers, furnaces, water heaters is provided by Carson Dunlop, Associates, Toronto - Carson Dunlop Weldon & Associates Special Offer: Carson Dunlop Associates offers InspectAPedia readers in the U.S.A. a 5% discount on any number of copies of the Technical Reference Guide purchased as a single order. Just enter INSPECTATRG in the order payment page "Promo/Redemption" space.
The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 25th Ed., 2012, 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. Field inspection worksheets are included at the back of the volume.
Special Offer: For a 10% discount on any number of copies of the Home Reference Book purchased as a single order. Enter INSPECTAHRB in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
Special Offer: Carson Dunlop Associates offers InspectAPedia readers in the U.S.A. a 5% discount on these courses: Enter INSPECTAHITP in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
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