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Identifying Building Envelope Problems

May 15, 2008

By definition, “envelope” is an
encapsulating covering such
as an outer shell or membrane.
In simple building
terms, it consists of the roof,
the above-grade wall system,
and the below-grade wall system. An envelope’s
purpose is to provide protection from
external elements, which, in building construction,
means protection from moisture,
air, and temperature ingress
and egress.
The definition sounds
simple enough, but in reality—
because of the thousands
of complex products and systems
specified and the multiple
trades involved—the probability
of error is high. As
complex and intricate as the
building envelope seems to
be, how can one determine if
a building envelope is going
to have or is already having
Proactive Investigations
In a perfect world, potential
owners would engage a
professional with building
envelope knowledge to in –
spect and determine the likely
building envelope investment
that might be required
before purchasing a structure.
Owners typically look at
the roof, but rarely examine
the remaining elements of the building.
With good information from an investigation,
a client can make a prudent business
decision prior to purchase. Armed with this
information, the client can negotiate the
price, decide to accept the risk while being
aware of the financial needs, or walk away
from the deal.
Unfortunately, proactive investigations
are still rare, especially when the economy
and real estate markets are booming and
deal making is fast and furious. A large
majority of calls are from owners who have
recently acquired structures, new property
managers, new condominium board members,
new church business managers, or
new building engineers — each of whom
has just taken over a property and found
that something is leaking or falling off the
A masonry inspection opening
14 • I N T E R FA C E J U LY 2008
Regardless of when and
from whom the call comes,
what is a good way to tell if
the building envelope is having
or will have problems?
Obviously, a building
must be seen in person, and
that brings up the question:
How closely does one need to
look? A good starting point is
covered by ASTM E 2270,
Standard Practice for Periodic
Inspections of Building Fa –
çades for Unsafe Conditions,
which defines the levels of
façade inspections to apply to
a building. Before the creation
of this standard term,
definitions and methods were
inconsistent throughout the
industry. This standard is
intended to establish a consistent
minimum requirement
for conducting periodic in –
spections of building façades
to identify unsafe conditions
that could cause harm to persons
and property. One of the
most inconsistent items was
the level of proximity required
to determine the access for an
inspection. This standard
establishes two options and
defines them at the very
beginning in section 3.2.9,
“Levels of Façade Inspec –
• Option 1: general
inspection involves
visual observation of
façade components
from distances equal
to or greater than six
feet, with or without
magnification or re –
mote optical devices,
• Option 2: detailed
inspection is the
visual observation from less than six
feet and tactile evaluation of façade
components, including probing and
nondestructive testing to observe
concealed conditions of wall construction.
Typically, the decision for a general
inspection is made because the detailed
inspection is too expensive or would take
too long, or a report is needed in a short
amount of time.
A building envelope investigator’s tool
kit should consist of the following: a good
carry bag (i.e., a hiker’s waist pack), a tape
measure, a rolling wheel, a camera, a notebook,
several color pens and markers, duct
tape, a voice recorder, and, most importantly,
personal protection equipment, including
a hard hat, safety glasses, and a pair of
The general inspection can be broken
down into four basic steps:
• Initial walkabout
• Knowledge gathering
• Interior symptoms
• Exterior signs
Initial Walkabout
A basic tour of the structure and cursory
visual examination should be performed
as the first step in the process. Next, title
three pages of notebook paper—one for the
wall system, one for the roof, and one for
J U LY 2008 I N T E R FA C E • 1 5
Sealant applied incorrectly at the window frame to trim and from trim to J bead
the wall system below grade. Use these
pages for initial notes to start the documentation
process (the camera generally is not
needed until Steps 3 and 4). This step is
used to get familiar with the structure so
that the inspector will have a mental picture
of the building, if and when he or she gets
to see the drawings.
Beginning with the wall system, it is
vital to walk around the structure to get an
understanding of its shape and makeup,
materials used, as well as any features such
as balconies, cornices, or ornamentation.
Also, check to see how the building is terminated
at grade. Next, continue to the roof
to see the layout. If it has a parapet, note
how the roof is terminated to the parapet,
how the roof is accessed, and the roof system
type. Finally, continue to the belowgrade
area of the structure to look for sump
pumps, smell for dampness, and determine
the foundation wall construction. Once the
brief walkabout is complete, it is important
to meet with the building manager, property
manager, business manager, and others
to start the next step: knowledge gathering.
Knowledge Gathering
Start this step by asking for a set of
drawings. Sometimes this is a challenge.
Before arriving, it is best to inform the
owner that drawings are going to be needed
so that they can be found and organized.
Hopefully, there are drawings to review, but
with older structures, they may not be
available. In this case, in order to access
some of the history of the structure, interview
management, maintenance staff, and
tenants, in addition to reviewing the maintenance
and project file. Also, ask for any
warranties; there is typically one for the
roof, but also ask for manufacturers’ warranties
for the window systems and the
below-grade waterproofing system.
Flip to sections with details on the wall
systems. First, try to identify the wall system
as a barrier wall or a water-managed
wall. (See ASTM E 2128, Standard Guide for
Evaluating Water Leakage of Building
Walls.) Barrier wall is defined as the mechanism
intended to prevent leakage in this
type of wall by blocking or interrupting the
movement of water to the interior. A watermanaged
walls is the mechanism intended
to prevent leakage by controlling and discharging
anticipated and accepted amounts
of water that penetrate the exterior surfaces.
If it is unclear or seems to be questionable,
be suspicious of the design details.
Next, check the details. If insufficient
details are pulled out of the wall sections to
show how to create terminations, penetrations,
and changes of plane for all of the
particular wall-system building materials, it
immediately throws up a red flag.
Unless the project had a high level of
quality field craftsmen or really good
inspectors, there may be some challenges in
the way field decisions were made in order
to make these details work. Also, shop
drawings should be part of the requested
drawings, especially for the windows if there
is a curtain wall. From the window shop
drawings, try to determine how the window
system is managing water. A lack of wall
details or a lack of shop drawings at any
time makes Step 3, Interior Symptoms,
more intense.
For the roof, always look at the system
type and check if the construction drawings
of the roofing system match the existing
conditions. If they don’t, has there been any
Interior damage at the jamb of a window
16 • I N T E R FA C E J U LY 2008
modification or repair? Also, if there
has been a modification, what, if anything,
has been done to the parapet
wall? Because parapets are exposed
to weather on three sides, there is a
greater chance of their having problems,
especially if the modifications
did not take into consideration the
original design intent. Identify the
number of drains and whether there
is an appropriate roof slope-to-drain.
How the through-wall scuppers are
detailed always should be reviewed,
especially if the scupper outlet is
directly at the vertical expansion
joint. Finally, locate the system specified
for the below-grade waterproofing
and see if any details were made
on termination, penetration, and
changes in plane.
Interior Symptoms
At this point, if the building management
has any knowledge of interior
water infiltration, severe cracking
of interior finishes, or both, now is
the time to take the observations
gathered in Steps 1 and 2 to identify
symptoms in the interior. Look for the Exterior signs of brick spalling
J U LY 2008 I N T E R FA C E • 1 7
following symptoms:
• Staining of the interior wall surfaces,
the wall system above the ceiling
tiles, or both
• Water-damaged insulation above the
ceiling tiles
• Stained ceiling finishes
• Water-damaged window soffits,
jambs, and sills
• Water stains on the floor finishes,
including rust stains from excessively
wet steel-stud baseplates
• Peeling of wallpaper
• Cracking of interior finishes
• Stains/dirt in operable window
• Water stains at the perimeter of the
AC units
• Mold
• Odors
Document the location of these interior
symptoms so that during Step 4, Exterior
Signs, a determination can be made as to
whether or not there is a direct correlation.
With regard to water infiltration, remember
that water does travel. As such, symptoms
are often not simply on the exterior of the
building. Here is where ASTM E 2128, Stan –
dard Guide for Evaluating Water Leakage of
Building Walls, is a tremendous resource.
Exterior Signs
Once information has been gathered
from the previous three steps, the inspector
will have a better understanding of what to
focus on during the review of the exterior
signs. For walls, the obvious big three are
bulging, spalling, and cracking. Following is
a brief list of other exterior signs to consider:
• The wall system has a cavity but the
flashing cannot be seen. Even if
drawings and in spection indicate a
flashing, if it cannot be seen in the
field by the naked eye, the in stal –
lation and/or functionality is suspect.
• Weep holes are caulked or mortared
• Weep tubes or weep wicks were
• The roof extends up the back of the
parapet wall.
• Rust marks are present at embedded
steel locations.
• Railing posts are set in concrete
• Cracks go through both the masonry
and the mortar.
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Roof run up the back of a parapet wall that created damage to the terra cotta cornice.
18 • I N T E R FA C E J U LY 2008
• Capstones have craze cracking.
• Capstones have inside and outside
bed joints and the cross joints are
caulked shut.
• Brick is spalling.
• Glazed brick is spattered with efflorescence
• Cracking exists through EIFS lamina.
• Post-tensioning ends with rust
• A white haze is seen on brick cavity wall.
• Efflorescence appears from cracks
in concrete or masonry.
• Grade is sloped toward the building.
• Rainwater conductors cut off and
run out on grade.
• Horizontal rust lines appear in mortar
• There is discolored stone or masonry.
• Windows and doors are racked.
• Door and window frames are rotted
or rusted.
• There are signs of condensation on
• Excessive mortar joint popping is
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Test your knowledge of building envelope
consulting with the follow ing ques tions
devel oped by Donald E. Bush Sr., RRC, FRCI,
PE, chairman of RCI’s RRC Examination
Develop ment Subcommittee.
1. What are the most
common failure modes
for modified bitumen
roofing membranes?
2. What is the key element
in the formulation of
3. What causes the
shrinkage of EPDM
4. Roof assemblies that do
not require sprinklers
include which types?
5. What is the distinction
between Class 1 and
Class 2 steel-deck
6. To determine a roofcovering
fire class ifi ca –
tion, what four tests
does UL use?
7. To qualify for classifi ca –
tion, the tested roof
covering must withstand
the four tests. What
results are required for
Answers on page 20
J U LY 2008 I N T E R FA C E • 1 9
• Caulking is smeared on mortar joints.
• There is step cracking off steel lintels.
• Carpets are glued down on exterior
horizontal concrete surfaces
• Terra cotta is painted and/or
• Glass-to-metal glazing has turned
into gum or has shrunk from the
window frame.
• Building sealant is compressed at
expansion joints
• Curtain walls or window systems are
• Surface alligatoring of the roof membrane
is apparent.
• Roof seam is split.
• There is a roof surface-applied termination
bar to a cavity wall.
• Overall roof drainage is poor.
• Expansion joints are incomplete.
If any of these signs match with any
symptoms identified in the previous steps,
there is a very good chance that the building
envelope faces some challenges. The
exterior signs without interior symptoms do
not mean there is not a challenge, but it’s
just a matter of time. In most cases, the
interior symptoms will occur at some point
in the life of the structure, so it is important
to continue monitoring these conditions.
In most cases, obvious building envelope
problems are easy to identify. In order
to identify the not-so-obvious signs (especially
if the interior symptoms have not
occurred or have not been identified), experience
in the repair of building envelope
deficiencies is priceless. Combine this with
the knowledge of architectural details, engineering
basics, good waterproofing practices,
as well as an inspection plan as outlined
above, and the owner will have the
best possible information about the building
envelope. This information can be used
as a tool to purchase a building, create capital
projects, or develop a maintenance
Answers to questions from page 19:
1. • Defective lap seams
• Shrinkage
• Checking
• Blistering
• Delamination
• Slippage
• Splitting
2. Carbon black – it provides
ultraviolet resistance and greatly
enhances tensile and tear
3. • A slow loss of processing oil
used in the manufacturing
• Residual tensile stress
(developed during the manufacturing
process when
the molecular cross-linking
• Insufficient relaxation of the
EPDM sheet just prior to
4. • Class 1 steel-deck assemblies
• Noncombustible decks:
concrete, gypsum, asbestos,
cement, and preformed
structural mineralized wood
5. The rating depends on the heat
release of the above-deck
6. • Flame spread
• Flame exposure
• Burning brand
• Flying brand
7. • There cannot be any portion
of the roof-covering material
blowing or falling off in
glowing brands; or
• Exposing the roof deck by
breaking, sliding, cracking; or
• Warping or permitting
ignition or collapse of any
portion of the roof deck.
Reference: Manual of Low Slope Roof
Systems, 4th Edition,
Chapter 8 and 12
Mark K. Howell is a recognized leader in the concrete and
masonry maintenance repair industry and has been involved
during the past decade in the investigation and restoration of
many contemporary and historic structures. He is employed
by Structural Preservation Systems in Baltimore, Maryland,
and can be reached at
Mark K. Howell
20 • I N T E R FA C E J U LY 2008
The Corporate Manslaughter and Corporate Homicide Act came into force
across the United Kingdom on April 6, 2008. It establishes a new offense for convicting
an organization where gross failure in management or organization
results in someone’s death. Organizatons can now face criminal prosecution and
unlimited fines.
In 2006-07, 32% of all worker deaths in the U.K. were in the construction
industry. Conviction under the former legal framework was next to impossible
because a company could be convicted only if the “directing mind” or senior individual
could be identified and found guilty for gross failings leading to the death.
Now prosecutors can look collectively at the actions of senior management.
A new guidance booklet of health and safety liabilities for employers in the
U.K. is downloadable from
— RCi
U.K. Corporate Homicide
Act in Effect