EVALUATING FOUNDATION CRACKS
(Round Table Discussion)
(
By
Bob Mulloy
(Note: Due Diligence: The client has expectations
that the inspector will identify concerns & defects.)
STANDARDS OF PRACTICE:
2. PURPOSE AND SCOPE
2.2B The inspector
shall:
Report:
1.The inspector shall
report on SYSTEMS and COMPONENTS which in the
professional opinion of the inspector are significantly deficient or are near the
end
of their service
lives.
2. a reason why, if
not self-evident, the systems or components is significantly
deficient of near the end of its service life.
3. the inspector’s
recommendations to correct or monitor the reported
deficiency.
3. STRUCTURAL SYSTEM
3.1 The inspector shall:
A. inspect:
1. the structural components including foundation and framing.
B. describe:
1. the foundation and methods used to
inspect the under-floor crawl space.
3.2 The
inspector is NOT required to:
A. provide any
engineering service or architectural service.
B. offer an
opinion as the adequacy of any structural
system or component.
General Comments:
All solid materials may both expand and contract in response to temperature variations. All solid materials may be cracked by pressure from loading.
All cracks need to be separated into those which are expected to require no further repair except possibly cosmetic (which can help future monitoring), those which merit ongoing monitoring for change and possibly signs of worsening conditions, and those which are so significant as to require repair.
Repair work needs to be identified with respect to urgency, ranging from immediate (risk of collapse or other unsafe conditions) and less urgent.
As you evaluate a crack, remember that cracks are time related and that you are only viewing the crack at one moment in time. Determining cracking speed is beyond the scope of a home inspection, but understanding that crack movement can be cyclical, decelerating, constant or accelerating will help an inspector to determine if the stability of the home is threatened. Look for evidence of repeated repairs and movement telegraphed upward into other parts of the structure.
NOTE: ANY crack associated with significant displacement of original structural or mechanical (gas/sewer lines) components is likely to be significant. Even slight displacement is significant if mechanical systems may be unsafe
WARNING: Don't make
conclusions just based on crack size and location. The inspector must consider
other site factors conditions, history, materials, external forces, etc. Sudden
catastrophes CAN occur, especially where site drainage or other conditions risk
undermining or sudden forces on the foundation.
TYPES OF CRACKS:
1. Shrinkage cracks
Can we agree on some rules of thumb?
Always evaluate the widest part of the crack
Shrinkage cracks are uniform in width.
Shrinkage cracking is usually due to poor mix and rapid curing.
Small cracks up to 1/16” are of no concern unless extensive.
Cracks from 1/16” to ¼” need moderate repair
Cracks ¼” and larger need immediate repair
1. V-shaped or tapered cracks
Wider at the top and diminishing at the base
The crack may extend into the footing and be a more immediate problem.
Indicates bending over a single point.
May be related to settlement during initial site factors or on-going settlement due to site
factors.
2. Diagonal cracks
Diagonal cracks indicate that the home has moved and that one part of the home has
shifted relative to another part. Diagonal cracks are usually at 45 degrees to the floor and
represent tension shear movement as the concrete breaks and slides into a new position. The top
of a diagonal shear crack points to a wall that has moved from its original position.
Often found on homes built on a slope
3. Differential cracks (movement in more
than one plane)
4. Step pattern cracks (usually indicate a footing failure)
5. Horizontal cracks
Usually high on a foundation wall
May be a result of wet soil and frost damage
May be the result of backfill damage
Usually only visible from within the basement or crawl space
SOME QUESITONS FOR DISCUSSION:
1.
How do you report
on a crack in a foundation?
Explicit description of observations should be provided with sufficient detail such that a qualified expert on reading the report, and on assuming that the report author did not miss other site clues, could agree that the inspector's conclusions were reasonable and prudent.
A home inspector should
make no pronouncements of “structural soundness” of building components. Do indicate whether or not you observed
indications of damage to the building. It
is proper to make recommendations to an engineer for reappraisal of the
problem.
2.
The client wants
to know if the crack is worrying about or not.
3.
You, the
inspector, want to gather all the evidence before judging what caused the
movement
Sources: Dan
Friedman’s web site www.inspect-ny.com
The Crack Detective, The