COMMON
NON-STRUCTURAL
FAILURES
State of Michigan P.A. 54 Approval # Pending
Class Category: Specialty
Registration Category: BI or Bo/PR but no inspector registration
Hours Approved: 3
Instructor – Larry Pickel: Approval # 121
DISTINCTION BETWEEN CONSTRUCTION
RELATED FAILURES
STRUCTURAL
• Relates to the primary
structural framing system
• Failure to carry or transfer
imposed loads
• Result is partial or total
collapse of the structure
• Primarily related to footings,
foundations, beams, rafters,
trusses and joists
NONSTRUCTURAL
• Relates to either
nonstructural or localized
component elements
• Failure results in additional
hazards to occupants short of
total collapse
• Begin as problems,
maintenance issues
• Eventually may grow to
become a structural failure
STRUCTURAL
NONSTRUCTURAL
Many nonstructural failures will
eventually become structural
failures given enough time and
lack of attention
Many nonstructural failures
will remain so if addressed in
a timely manner by
competent personnel
FACTORS CONTRIBUTING to CAUSES of
NONSTRUCTURAL FAILURES
LAPSES or
CARELESSNESS
IGNORANCE
Lack of proper coordination;
general negligence;
conscious risk taking
RISK
ECONOMY
Lack of sufficient
information; lack of
competence; lack of
supervision or
precedent
UNUSUAL
OCCURRENCES
In first cost; in maintenance
Earthquakes; extreme storms,
fires; floods; explosions;
sabotage
Based upon:
The Nature of Structural Design & Safety
Building Failure
Blockley, D.I.
McKaig, Thomas H.
RELATIONSHIP OF MAIN CODES
DEALING WITH NONSTRUCTURAL FAILURE
IBC
B 101.4.5
B 102.6
B 103.3
B 3401.3 & 3.2
IPMC
B 101.4.6
B 102.6
B 201.3
+
R 102.7
IRC
R 102.7
IFC
B 101.4.5 Property maintenance.
The provisions of the International Property Maintenance
Code shall apply to existing structures and premises;
equipment and facilities; light, ventilation, space
heating, sanitation, life and fire safety hazards;
responsibilities of owners, operators and occupants; and
occupancy of existing premises and structures.
B 101.4.6 Fire prevention.
The provisions of the International Fire Code shall apply
to matters affecting or relating to structures, processes
and premises from the hazard of fire and explosion
arising from the storage, handling or use of structures,
materials or devices; from conditions hazardous to life,
property or public welfare in the occupancy of structures
or premises; and from the construction, extension,
repair, alteration or removal of fire suppression and
alarm systems or fire hazards in the structure or on the
premises from occupancy or operation.
R 102.7 Existing structures.
The legal occupancy of any structure existing on the
date of adoption of this code shall be permitted to
continue without change, except as is specifically
covered in this code, the International Property
Maintenance Code or the International Fire Code, or as
is deemed necessary by the building official for the
general safety and welfare of the occupants and the
public.
Administration
Exterior /Interior
PME
Fire safety
IPMC
IFC
1
3
5- 6
7
1
3
6
7
8
9
10
CORRELATION OF
PRIMARY CODE
SECTIONS
Administration
General
precautions
Services / systems
Fire resistance
rated construction
Interior finishes
Fire protection
systems
Means of egress
CODE APPLICATION
Administration
1
PM
IPMC: 101.2 Scope.
The provisions of this code shall apply to all existing
residential and nonresidential structures and all existing
premises and constitute minimum requirements and
standards for premises, structures, equipment and facilities
for light, ventilation, space, heating, sanitation, protection
from the elements, life safety, safety from fire and other
hazards, and for safe and sanitary maintenance; the
responsibility of owners, operators and occupants; the
occupancy of existing structures and premises, and for
administration, enforcement and penalties.
Administration
IFC:
1
F
101.2 Scope.
This code establishes regulations affecting or relating to
structures, processes, premises and safeguards regarding:
1.
The hazard of fire and explosion arising from the
storage, handling or use of structures, materials or devices;
2.
Conditions hazardous to life, property or public
welfare in the occupancy of structures or premises;
3.
Fire hazards in the structure or on the premises from
occupancy or operation;
4.
Matters related to the construction, extension,
repair, alteration or removal of fire suppression or alarm
systems.
General
1
102.2 Maintenance
Equipment, systems, devices and safeguards required
by this code or a previous regulation or code under
which the structure or premises was constructed,
altered or repaired shall be maintained in good
working order.
PM
CATEGORIES OF
NONSTRUCTURAL FAILURES
FAILURE of
MATERIALS
Wood, masonry &
concrete
FAILURE of
FAILURE of
ENVELOPE or
COMPONENTS
Roofing, ice dams,
flashing, siding, EIFS
SYSTEMS
Plumbing,
mechanical,
electrical
FAILURE of
FIRE SAFETY
MEASURES
Occupancy, construction
type, fire resistance, fire
protection systems, means
of egress
CLASSIFICATION of ENGINEERING MATERIALS
CERAMICS
ORGANICS
IONIC BOND
COVALENT BOND
Inorganic, nonmetallic, crystalline compounds
Positive and negative ions in a stable arrangement
Chemically inert
High melting points
Brick, tile, cement, stone, clays, gypsum, glass
An organic, non-crystalline material
Mutual sharing of outer valence electrons
Bond easily altered by heat or force
Low strength, low melting points
COMPOSITES
Made of two or more materials from
other groups
Usually one material acts as a binder,
one acts as a reinforcement
Concrete, fiberglass, alloy steel
METALS
METALLIC BOND
An inorganic substance made up of one or
more metallic elements
Close packed, crystalline structure
Ions are stable within a dispersed “sea”
Strong, high melting points
Copper, iron, aluminum, zinc, tin
Wood, plastics
Mainly carbon + hydrogen atoms also known as
hydrocarbons.
Hydrocarbons arranged in long chains:
Natural: wood, cotton, wool, silk
Synthetic: thermoset & thermo plastic
COMMON NONSTRUCTURAL
WOOD FAILURE
WHITE
ROT
BROWN
ROT
INSECT
DAMAGE
Sometimes mistakenly
referred to as “dry” rot – a
misnomer since moisture is
required for rot to occur
OTHER
MASONRY
FAILURE of
MATERIALS
Ceramic material-clay or shale formed, dried and fired
Extruded (stiff mud) – Major method of production
All bricks have similar chemical compositions
Clays all composed of silica and alumina with metallic
oxides in varying amounts
Brick construction considered homogenous.
Bonded into integral mass by mortar, grout, steel.
Behavior of the “combination” that determines integrity.
Assembly more important than component.
Interaction of materials determines performance.
COMMON NONSTRUCTURAL
MASONRY FAILURES
CRACKING
WALL MOVEMENT
EFFLORESCENCE
LOSS OF INTEGRITY
MASONRY CRACKING
“Nonstructural cracking” leads to structural cracking
Cracking associated with thermal / moisture movement.
Expansion contraction cycle.
Stresses built up in walls that must be resolved.
Wide variety of cracking patterns.
Most common are vertical and horizontal shear pattern.
Cracks typically open and close cyclically.
Damage always left behind.
Unit nature of masonry – lots of edges and surfaces.
Inherent weak nature of the mortar / masonry bond.
Typical shear failure modes, both vertical and horizontal.
Vertical usually due to settlement.
Horizontal due to wind or expansion/contraction cycles.
Cracking associated with horizontal shear
Between upper wall and wall entering the ground
Differing rates of thermal expansion
Cracks will take line of least resistance
Vertical / diagonal cracking at end walls
Usually due to thermal movement
No tensile strength in wall to “pull” end wall along
Classic 45° shear crack pattern
radiating from atop a window lintel
and near the end of the building
Common thermal / moisture masonry wall crack
Thermal expansion crack showing loss of vertical mortar
integrity and opening for further damage
Cracking associated with water penetration
Cracks at or along
areas near sills and
lintels
Can be due to use
of dissimilar
materials
Can be due to poor
detailing
Can be due to loss
of integrity of
lintel itself
Exterior / Interior
3
304.2
All metal surfaces subject to rust or corrosion shall be
coated to inhibit such rust and corrosion and all
surfaces with rust or corrosion shall be stabilized and
coated to inhibit future rust and corrosion. Oxidation
stains shall be removed from exterior surfaces. Surfaces
designed for stabilization by oxidation are exempt
from this requirement.
PM
Thermal crack at mortar joint showing exposed
reinforcing
Cracking associated with rusting or iron/steel
Corrosion of embedded metals creates rust
Expansive force builds up on surface of metal
Places pressure on surrounding masonry / displaces it
Rusted shelf angle
Movement begun by
rusting of shelf angles
and lintels at
perimeter of structure
Window lintel corrosion causing movement
Rusting lintels causing a swelling of the
surrounding brick surfaces
MASONRY EFFLORESCENCE
Efflorescence is a
process.
Visible as a crusty,
white salt deposit
leached to the
surface.
Requires presence
of salt and moisture
Salts are present in
the mortar, bricks
and blocks.
Salts are carried to the surface and left behind after the
evaporation of the water
Efflorescence and water damage on brick steps
Resultant loss of surface material due to excessive
efflorescence and moisture movement
Internal efflorescence and damage due to moisture migration
MASONRY LOSS OF MASS INTEGRITY
Unit masonry, mortar and
reinforcement act as a unit
and failure of any part
usually results in subsequent
failure of the assemblage.
Localized failure areas caused by a variety of sources.
Loss of integrity due to moisture migration and
improper tooling of the joints
Extensive loss of bond between brick and mortar.
Hard, low suction brick; high cement mortars;
improper tooling of the joints.
Spalling and
movement due to
moisture
penetration of the
masonry wall
CONCRETE
FAILURE of
MATERIALS
3–8%
Air
Coarse
Aggregates
Cement
15 %
31 %
Fine
Aggregates
28 – 30 %
Water
18 – 21%
COMMON NONSTRUCTURAL
CONCRETE FAILURE TYPES
DUSTING
SCALING
CRAZING
CRACKING
BLISTERS
DELAMINATION
DISCOLORATION
Some cracks do lead to progressive deterioration.
CATEGORIES OF
NONSTRUCTURAL FAILURES
FAILURE of
MATERIALS
Wood, masonry &
concrete
FAILURE of
FAILURE of
ENVELOPE or
COMPONENTS
Roofing, ice dams,
flashing, siding, EIFS
SYSTEMS
Plumbing,
mechanical,
electrical
FAILURE of
FIRE SAFETY
MEASURES
Occupancy, construction
type, fire resistance, fire
protection systems, means
of egress
COMMON NONSTRUCTURAL
BUILDING ENVELOPE FAILURES
ROOFING
ICE DAMS
FLASHING
SIDING
EIFS
Estimated that 99% of envelope failures
involve intrusion of WATER
Some effects of unwanted water on the building:
• Adds weight to the structural system
Increases /alters load distribution path
• Creates energy loss adding to energy bills
Wets materials as it moves
Damages building skin and interior
Creates new gaps and paths for air / water
• Sustains rotting and corrosion of materials
Frequently hidden and silent damage
• Degrades connections and attachments
Weakens connecting materials at joints
ROOFING
FAILURE of
ENVELOPE or
COMPONENTS
Common roofing system types:
• BUILT-UP ROOFING (Multi-ply)
• MODIFIED BITUMEN
• SINGLE PLY MEMBRANE
Elastomeric (EPDM) bonded by adhesives
Thermoplastic (PVC) heat welded
• ASPHALT SHINGLES
Exterior / Interior
3
304.7 Roofs and drainage.
The roof and flashing shall be sound, tight and not have
defects that admit rain. Roof drainage shall be
adequate to prevent dampness or deterioration in the
walls or interior portion of the structure. Roof drains,
gutters and downspouts shall be maintained in good
repair and free from obstructions. Roof water shall not
be discharged in a manner that creates a public
nuisance.
PM
BUILT-UP ROOFING PROBLEMS
Old reliable commercial roofing system.
Buildings with low-slope or “flat” roof structures.
Started in the 1840's.
Often referred to as "tar and gravel" roofs.
Multiple plies of roof felts laminated together with bitumen.
Felts are organic-fiber, fiberglass, or polyester felt.
Top-surfacing or a glaze coat of asphalt, gravel or slag.
Some use a granule-surfaced cap sheet.
Blisters are the result of a void created either between
the felt plies or the membrane and substrate.
Membrane surface then slides, exposing bitumen / plies
Splitting of a built-up
membrane develops from
the bottom up.
No real advanced warning.
General cause is a
concentration of stress.
Insulation boards move,
buildings settle, substrates
shrink and roofing cannot
accommodate the
movement.
Small hole (Possibly
from a careless
dropped screw
driver) in built-up
roof with 72 Lb.
granulated cap
sheet.
Blisters in this asphalt mopped built-up roof membrane
system caused from age and from standing water weight.
Recent ceiling damage to the Unity Temple in Oak Park, Illinois
designed by Frank Lloyd Wright. The result of a flat roof, decayed
over time, and drywall directly attached.
MODIFIED BITUMEN ROOFING
PROBLEMS
Asphalt-based, close cousin of the Built-up-Roof (BUR) .
Originated in Europe in the mid 1960's.
Used in the United States and Canada since approx. 1975.
Blend of synthetic rubberized polymers with asphalt.
Use of fiber-reinforced base sheets.
Increased resistance to brittleness at cold temperatures.
Numerous surfacing options include a factory applied
mineral surface, gravel surface, “cool roof” coatings.
Older version of a modified bitumen roof
Example of seams done very well, smoothly
Single largest problem - defective lap seams.
Open seams occur due to inadequately heated asphalt.
Positive bond rarely achieved with lower temperatures.
Membrane shrinkage is another inherent weakness.
SINGLE-PLY MEMBRANE PROBLEMS
Grown in popularity as a preferred commercial system.
Membranes are large, strong, flexible sheets.
Membranes are joined by adhesives or heat welded.
Predominately synthetic polymer.
Generally consistent quality of membrane/accessories.
Importance in following manufacturers instructions.
Many membranes highly-reflective “cool roof” surface.
Membranes prior to welding into monolithic seams
Single ply PVC membrane roofing system
Problems include shrinkage of
the membrane, especially in
those laid loose or ballasted.
Durable bonds are difficult to
achieve with certain
chemically inert membranes.
Incorrect flashings and failure
of flashings caused by
shrinkage of the membrane.
Mechanical damage such as
puncturing from surface
traffic, tools, and from below
from protruding fasteners.
Flashing laid in a non-shingle fashion has failed and
begun to affect this early EPDM membrane roof
ASPHALT SHINGLE PROBLEMS
Asphalt granules
Slow the flow of water
Reduce the erosion across the shingle
Shield the asphalt from direct sunlight
Developed over a century ago.
Originally organic base of wood fiber and asphalt.
Today fiberglass reinforced shingles dominate market.
Available in basic “three-tab” design
Middle-range “dimensional” or “laminated” shingle
Thickest are “top-of-the-line” heavyweight
BARESPOTS
Loss of mineral granules on the surface of the shingle.
Loosening of a protective coating – reduces shingle life.
Granules protect shingle from sunlight and slow runoff.
Shingles become porous where granules are washed off.
May cause shingle to leak into substrate material.
Freeze / thaw cycles may accelerate in areas of granule loss.
Some damage may be caused by workers / walking.
Some loss due to storms / hail.
Some loss due to other conditions including blistering.
Massive area of loss from multiple factors including weather
An under-ventilated attic, showing the roof surface
granule loss from being “baked” from beneath.
BLISTERS
Small areas of bubbling shingle surfaces.
Tops usually loose granules and begin to expose substrate.
Some manufacturers claim blistering is aesthetic only.
Some insist it is not a manufacturing defect.
Potential shingle wear pattern at blister sites.
Characteristic of granule loss at these areas.
Estimated by some 5% - 15% shingle life reduction.
Blister has deteriorated and “popped” exposing substrate.
BUCKLING aka.
FISHMOUTHING
Distortion of the shingle generally in the center.
Curves upward in similarity to the mouth of a fish.
Isolated cases can occur when nails are under-driven.
Isolated cases also occur when nails back out of a deck.
General views of a fish
mouth buckling
pattern
Larger areas usually indicate a systemic building problem.
Usually combination of roof moisture / ventilation defects.
Occur typically over butt joints between individual shingles.
Excessive under-roof moisture usually suspected.
Poorly or un-vented attic of roof cavity.
Moisture escapes at the joints and at the surface mid-tab.
Moisture loss “uneven” and leads to an isolated raised portion.
CLAWING
Leading edge of the shingle strats to draw under itself.
Creates a “clawing” like profile.
Typically as shingles age - generally only near end of life.
Diagram of typical clawing pattern
CRACKING
Actually a tearing of the shingles in most cases.
Cited by some as the principal current problem with
fiberglass-based roof shingles.
Some due to lack of compliance with ASTM Standards.
Fiberglass mat may lack tear resistance capability.
Variety of patterns: horizontal and vertical.
Also possible due to excessive bonding of adhesives.
Creates a single, large, stiff roof membrane diaphragm.
Roof is not resilient, is unable to flex with movement.
Freeze / thaw temperature cycles important variant.
CUPPING
Raised edges curl downward leaving concave center.
Normal wear pattern showing up on shingle with age.
Shingle has become fragile and near the end of life.
Extremely fragile, cupped edges.
CURLING
Curling up at the edges of the shingle tab.
Again usually due to aged, worn out shingles.
Curled and cupped shingles may be present on same roof.
Cupped and curled
roofing surface
GROWTHS
Algae, fungus, lichens, moss all may grow on shingles.
Hold moisture against the roof surface.
Accelerate deterioration during freeze / thaw cycles.
Much more than a simple cosmetic issue.
Moss related to absence of sunlight / presence of shade.
Lichens much stronger to grip than moss.
Cleaning process risks more harm to shingle surface.
A roof in need of complete replacement showing
growth along with advanced shingle decay