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Roof Management Program for Multiple Systems

May 15, 2008

INTRODUCTION
Roofing practitioners have long ac –
knowl edged that successful low-sloped roofing
performance relies on a combination of
four key elements; namely: sound design,
suitable materials, good workmanship, and
proper and timely maintenance.1
Historically, in spite of such acknowledgement,
little attention has been paid to
putting this tenet into practice, particularly
with regard to maintenance. For example,
almost 20 years ago, Firman chastised that,
in general, the industry was geared toward
new and reroof construction, with very little
emphasis given to maintenance needs.2 He
further stated that owners were mainly
responsible for this because they were not
demanding an emphasis on maintenance.
The result, in his opinion, was that owners
contributed to most roof leaks due to lack of
maintenance. Reasons for this attitude have
not been explored, but these authors
believe that it was associated with a shortsighted,
outright unwillingness to allocate
the funds necessary to perform the needed
maintenance.
Fortunately, as time elapsed, many
practitioners awoke to realize that the roof
represents a sizeable investment that needs
to be protected. They began to promote roof
maintenance management programs as a
formal mechanism for doing so. Bradford
evidenced this shift in attitude clearly and
succinctly in 1996 when he called the need
for roof maintenance “indisputable.”3 To be
sure, we can readily say in 2008 that widespread
use of roof maintenance programs
has been realized in the United States. Here
we cite Bradford’s 2004 writings that during
the past several years, roofing contractors
and roof consultants have seen substantial
increases in requests for preventive maintenance
services.4 He also opines that almost
everyone in the roofing business—from
manufacturers to consultants to contractors
of every size—has seemingly developed
a program, system, or department to
address owners’ roof system maintenance
needs. Today, any building owner in the
U.S. can search the Internet for “roof maintenance
management” and find Web sites
for hundreds of firms that offer such services,
ranging from limited inspections and
repairs to full management.
The objective of a roof maintenance program
is to extend the expected useful life
(EUL) of a roof system.5 The elements comprising
such a program are periodic inspections,
routine maintenance and repair, and
correct application of quality roofing products.
6
One of the first major organizations in
the United States to adopt a formal roof
maintenance management program was the
U.S. Air Force (USAF).7 Although controversial
because of some of its requirements, a
generally accepted feature of the USAF program
was the assignment of a quantitative
rating of the condition of a roof as determined
through its inspection. In turn, the
individual ratings for a number of roofs at a
facility were used for ranking their relative
conditions to establish priorities for completing
necessary repairs.8 Such prioritization
is particularly important in the case of
multibuilding complexes. Today, many
maintenance programs incorporate roofcondition
ranking systems for determining
the allocation of maintenance funds.
In the United States, perhaps the most
widely known maintenance management
program is the ROOFER Program of the
U.S. Army Corps of Engineers (USACOE).9
This program, which incorporates relative
ratings of roof condition among its many
features, is not only used at Army facilities
but also has been adopted by and adapted
to the private sector. Such programs can be
costly due to the amount of information
needed to populate the database. Today’s
computer technology has aided in the development
of maintenance programs, but at
the same time, has increased the amount of
information that is entered. The cost to
obtain the data is sometimes the governing
factor, exceeding the cost of the software
itself.
This paper presents an overview of a
newly developed roof maintenance manage-
12 • I N T E R FA C E NO V E M B E R 2008
Editor’s Note: This article was originally published as “Roof Management Program for Multiple Roof Systems”
in the Proceedings of the 11th International Conference on the Durability of Building Materials and Components
held in Istanbul, Turkey, May 5 – 11, 2008. Republished with permission.
ment program for use on multibuilding
complexes such as campuses, military
bases, and office parks. Examples of its features
are given from limited practical experiences
in the field. The goals of this program
are to prioritize roofs, train on-site
personnel, and simplify the process. One
key feature of this program–consistent with
those developed, for example, by the USAF
and the USACOE–is the inclusion of a
quantitative ranking of a roof’s conditions.
Another key feature is the training of on-site
personnel and the use of those trained personnel
in conducting the inspections.
Regarding this latter feature, we note with
interest that Sinderman, in his article discussing
roof maintenance management,
quoted a U.S. consultant as saying that a
lot of maintenance “is just having someone
walk your roof who is competent, trained,
and knows what to look for and how to evaluate
repairs.”10
ROOF PRIORITIZATION SCHEMA FACTORS
The foundation of the program presented
here is the delineation of ten factors used
in ranking the relative conditions of the
roofs (entire buildings or roof sections at
one building) inspected. These ten factors,
referred to as the “Roof Prioritization
Schema,” are, in no particular order:
• Age (EUL of the existing roof system)
• Importance factor (use of the
building under the roof area)
• Susceptibility to damage (roof traffic
indicator)
• Membrane condition (existing
membrane)
• Flashing condition (existing flashings)
• Attachment (type of attachment)
• Slope and drainage (slope to drains
and general roof slope; size/amount
of drains, gutters, scuppers, etc.;
and function)
• Constructability (difficulty of
repairs/replacements)
• Leak history (observed or reported
leaks)
• Durability (existing membrane
toughness)
These factors are scored on a relative
scale of 1 to 10, based on a ranking system
developed for this program. In general, a
score of 1 for a factor is a poor rating, and a
score of 10 is a good rating, except as noted
in the descriptions that follow. The methodology
behind the prioritization schema is to
aid in development of recommendations
and prioritization of maintenance needs
and roof replacement scheduling. The documentation
provided in AFI 32-105111 can
serve as a primer for evaluations performed
with these factors in mind. The technical
basis for each of the factors in the ranking
system is as follows:
Age Factor
While the age of a roof system may seem
like a fair indicator by which to measure a
roof’s performance, not all systems age the
same. Therefore, having a multibuilding
complex with various different EPDM, single
ply, gravel-surfaced built-up roof
(GSBUR), metal, and other types of roof systems
of varying ages presents the question,
“How old is too old?” For the purpose of
scoring on the basis of age, roofs are rated
on the expected useful life of the existing
membrane as compared to the current age.
For example, the expected EUO of an EPDM
membrane system is approximately 12-15
years;12 therefore, a six-year-old roof would
get a score of 5, while a one-year-old roof
would result in a score of 9. A built-up roof
has a EUL of about 25-30 years; therefore,
a 12-year-old roof would receive a score of
5, while a 24-year-old roof would get a 1.
Based on the authors’ experience, a
minimal percentage of roofs fail extremely
prematurely, within one to two years. Con –
versely, we have seen a similar minimal percentage
of roofs fail after extremely long service
lives of perhaps 30 years. The largest
number of failures seen in practice tend to
occur within one standard deviation of the
average failure age. Using EPDM as an
example and taking the average failure age
to be 12 years with a three-year standard
deviation, approximately 60% of EPDM
roofs might be expected to fail within 9 to 15
years. Similar predictions based upon our
experiences have been established for the
other types of roofs. However, with the
longer service lives of many roof types, the
range of the statistical failure point (standard
deviation) increases, resulting in larger
ranges for the expected failures. Table 1
summarizes the EULs of some typical roof
systems based on the authors’ field experiences
and complemented by data from roofing
literature.
Importance Factor
This ranking prioritizes roofs based
upon the function of the building use or
occupancy. That is, the level of importance
is rated by how important the roof integrity
is to the operation of the space below and
how the occupants would be impacted by
roofing damage or failure. For example, a
building housing sensitive electronic gear
would score a 1 (i.e., failure is worse here),
while a building housing spare machine
parts would score a 10 (i.e., failure results
in little damage).
NO V E M B E R 2008 I N T E R FA C E • 1 3
*Note: The EUL shown assumes a minimal roof slope of ¼ in per ft. Ranking Factor = ([Upper End of EUL-Age]/Upper End of EUL) x 10
Source: Author’s experience, Cash13, and Schneider14
Table 1 – Expected useful life (EUL) scoring.
ROOFING SYSTEM SURFACE TYPE EUL* SCORE FOR
10-YR-OLD ROOF
Built-up (3- or 4-ply) Gravel 25-30 yrs 7 = ([30-10]/30) x 10
Modified bitumen (2-ply) Granules 20-25 yrs 6 = ([25-10]/25) x 10
Single-ply (TPO, heat-welded PVC) Unsurfaced/exposed membrane 15-20 yrs 5 = ([20-10]/20) x 10
Single-ply (EPDM, adhered) Unsurfaced/exposed membrane 10-15 yrs 3 = ([15-10]/15) x 10
Metal (standing-seam) Fluoropolymer paint 40 yrs 8 = ([40-10]/40) x 10
Susceptibility to Damage
This factor addresses the probability of
damage due to concerns such as foot traffic
and surrounding conditions (overhanging
trees, runways, taxiways, adjacent buildings,
etc.). Are there multiple mechanical
units on the roof that require access? Are
there pavers or walkpads to protect the
roof? Are traffic paths clearly identified?
Each of these different types of traffic can
cause undue stress on the roof system.
Table 2 is a general rating system of the
resistance of a roof surface relative to roof
traffic and a general guide to scoring roofs
with respect to this factor. Note that the
metal roof system is scored based on the
possibility of paint scraping, denting of panels,
the possibility of seams being bent, etc.
Membrane Condition
This is a subjective view of the membrane
based on the inspection of each roof
for defects. The number, type, and extent of
defects are included in the rating. Table 3
summarizes typical defects for roof systems.
A membrane in good condition could
score “10,” even if the membrane is 30 years
old. A membrane in poor condition could
receive “1,” even if it were relatively new. The
key in this factor is not to take extensive time
to document each deficiency, but rather to
use the general visual inspection to provide
a relative magnitude of the defects. In our
experience, with training, most facilities personnel
can subjectively rate a membrane
condition to a reasonable degree of consistency.
Flashing Condition
In general, the assessment of flashings
is similar to the assessment of the membrane
insofar as the number, type, and
extent of defects are included in the rating.
Two important concerns not associated
with membranes but included in flashings
are the vertical attachment method and the
counterflashing. Vertical flashings should
be attached with continuous terminations.
Counterflashings should be provided. The
lack of either of these may necessitate the
assignment of a lower value in this category.
Flashings that do not appear to be performing
well are to be rated lower than
those that appear to be watertight and performing
well.
ROOF SYSTEM SURFACING TRAFFIC RESISTANCE LOW HIGH LOW HIGH LOW HIGH
Built-up Gravel High 10 8 10 8 10 8
(3- or 4-ply) Smooth-surfaced Moderate to high 9 6 9 6 9 6
Modified bitumen Gravel High 10 8 10 8 10 8
(2-ply) Granular-surfaced Moderate to high 9 7 9 7 9 7
Smooth-surfaced Moderate to high 9 6 9 6 9 6
Single-ply Exposed membrane Low to moderate 7 5 7 5 7 5
Ballasted Low to moderate 7 4 7 6 7 4
Metal Fluoropolymer paint Low to moderate 8 6 8 6 8 5
PMA Ballasted High 10 9 10 9 10 9
ROOF SYSTEM TYPICAL DEFECTS
Built-up Exposed felts, wind scour, blisters, asphalt migration (down slope), ply slippage (down slope),
(3- or 4-ply) exposed embedded metal, inadequately filled pitch pockets, splits, or tears.
Modified bitumen Open seams, inadequate bleedout, exposed bleedout, blisters, fishmouths, wrinkles, exposed
(2-ply) reinforcing scrim, loss of granules, inadequately filled pitch pockets, punctures, tears, or splits.
Single-ply Open-lap seams, short-lap seams, fishmouths, wrinkles, inadequately filled pitch pockets,
(heat-welded polymer) punctures, tears, or splits.
Single-ply Open-lap seams, short-lap seams, fishmouths, wrinkles, inadequately filled pitch pockets,
(adhered rubber) punctures, tears, or splits.
Metal Open seams at standing seams, missing or backed-out fasteners, buckling of pans, scratches, dents,
(standing-seam) or corrosion.
Table 2 – Resistance to roof traffic.
FT = Foot Traffic; SC = Surrounding Conditions; Access = Ability and/or need to access the roof.
RELATIVE SCORE
FT SC ACCESS
Table 3 – Typical roof membrane defects.
14 • I N T E R FA C E NO V E M B E R 2008
Attachment
Attachment provides resistance to wind
loads, and most design codes have very specific
requirements for wind-uplift resistance.
Attachment methods are at times
compromised by force-fitting a particular
attachment method to a roof deck that does
not readily lend itself to the method. Figure
1 shows the three most commonly used
attachment methods. The fourth method
shown, the protected membrane assembly,
is a hybrid of the basic attachments in that
while the membrane may or may not be
fully adhered, the insulation clearly
requires the ballast to keep it in place.
Deficiencies in attachment are a cause
of roofing failures. Membrane blow-off
causes failure of the weatherproofing system
at the very least and can be accompanied
by structural failure of the roof under
certain circumstances.
Another example is failure of the attachments,
causing failure of the waterproofing
membrane. Examples include fasteners
backing out through the membrane or fasteners
penetrating the deck and causing
condensation and water issues in the
spaces below.
Either deficiency can have significant
adverse effects on the long-term use of the
existing roofing installation. Evaluating the
appropriate attachment method for the specific
type of deck and evaluating the condition
of the attachment devices are critical to
the long-term performance of the deck.
Attachment is evaluated by comparing
an appropriately attached roof system with
no apparent failures (score of 10) with an
inadequately fastened but functional system
(score of 5) with fastener backout puncturing
the membrane (score of 1). Typically,
fastener defects are difficult to detect in a
surface visual review of the roof. For this
reason, it becomes important that the personnel
performing the rankings also perform
review of the construction documents,
looking for fastening requirements. He or
she should also access the interior of the
building to attempt to verify fastening type
and pattern from the underside of the deck.
In our experience, this factor is likely to be
evaluated as either a 10, a 5, or a 1 by most
assessors.
Slope and Drainage
Slope is an important factor in the proper
function of a roof system. Adequate slope
can compensate for inferior materials and
construction quality; therefore, a roof with
positive slope to drain (greater than ¼ in
per ft) should receive a higher score than
one with less slope. The waterproofing ability
of the membrane is less likely to be compromised
through draining of water quickly
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NO V E M B E R 2008 I N T E R FA C E • 1 5
Figure 1 –
Attachment methods.
away from the roof surface. Roof drainage
and slope are two distinctly different parameters.
An adequately sloped roof can have
inadequate drainage, and a flat roof deck
can have adequate drainage. Inadequate
drainage on a well-sloped roof can lead to
slower water runoff, taxing the flashing systems
and potentially leading to leaks. A relatively
flat roof system can have adequate
drainage, which becomes a requirement
when designing protected membrane
assemblies. Well-sloped roofs with minimal
or no indications of ponding should score a
10, while no-slope roofs with extensive
ponding should score a 1.
Drainage is an important factor in the
proper functioning of a roof system. Drain –
age refers to the ability of the system to
carry water away from the roof and the
building. The building code usually dictates
the minimum level of drainage required for
a roof. Conventional design calls for at least
four drains for larger roofs, a minimum of
two drains for roofs under 10,000 square
feet, and a maximum spacing of 75 feet in
any direction for drains. Roofs that meet
these criteria should receive a higher score;
those not meeting the requirements should
be scored lower. In addition, drainage covers
the adequacy and function of the existing
roof drains. Drains that are clogged,
that inadequately carry water away from
the roof and building, or that overflow during
severe events, should be scored appropriately
lower when drainage is evaluated.
Those with good drainage adequate for the
flow of water and well placed to divert water
from the roof and building score a 10, while
roofs with minimal drainage that retain
water score a 1. Scoring within the slope
and drainage category should be an average
of the 1 to 10 recorded for slope and the 1
to 10 recorded for drainage.
Constructability
This factor is associated with the
human element of postponing needed
repair or renovation of failed roof systems
only because they are difficult to access. In
our experience with multibuilding complexes,
the more difficult it is to reach a roof,
the longer the replacement is avoided. To
overcome this tendency toward procrastination,
we rank relatively inaccessible roofs
with lower values than those that are readily
accessible. Constructability refers to the
factors involved in maintaining or replacing
a particular roof, taking into account building
location, height, type, roof location and
number, use, and occupancy. Roofs on
taller buildings are more difficult to access
than those on lower buildings. A building
located in cramped conditions with inaccessible
edges will be more difficult to replace.
Roofs that can be easily and readily
replaced or repaired due to their location,
height, use, etc. should be scored at 10.
Those that will be difficult to replace due to
inaccessible locations or extensive restrictions
should be scored at 1.
Leak History
Leak history can be quickly determined
based upon interviews with building occupants
or by visual inspection of the interiors.
A roof that leaks extensively each time
it rains scores a 1. A roof that never leaks
would score a 10. Scores between 1 and 10
are based on a count of the number of leaks
and a comparison of the total number of
leaks at each building across the complex.
It should be noted that the leaks need to be
considered purely on number, not on what
is damaged. Additionally, the determination
of leak history scoring could be augmented
with knowledge gained from nondestructive
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16 • I N T E R FA C E NO V E M B E R 2008
evaluation (NDE) such as infrared or nu –
clear moisture scanning, if performed; however,
NDE is not necessarily a requirement
for completion of the ranking system.
Durability
Material durability refers to the roof’s
ability to resist weathering and natural or
man-made impact without breaking down.
Membrane type, thickness, and surface
treatment have significant effects on system
durability. The membrane and surface
must have the capability to ex pand and
contract to prevent splits and tears from
extreme temperature changes. This capability
must be present when a roof is constructed
and remain at adequate levels
throughout the EUL of the roof. Thus, in
order for a system to perform adequately, it
must have adequate material durability
when it is constructed and not have a tendency
to lose those characteristics as it
ages.
For the most part, membrane materials
today possess the material durability to
resist weathering and building-related
movement. However, some roofing materials
may not be suitable for the climatic conditions
of the site. A relatively thin, single-ply
membrane that is suitable for the sunny,
mostly dry climate of the southwestern
United States is likely inadequate for a mid-
Atlantic U.S. environment where large seasonal
swings in temperature are experienced.
A particular assembly that is used in
environments where insulation is not needed
or used may not be appropriate in a
heavily insulated roof. Often, manufacturers
have multiple products for numerous
surfacing configurations. Table 4 provides a
summary of the authors’ durability scoring
methodology used in this prioritization
schema. These scores are based on the
authors’ experience and relate similarly to
the age-scoring EUL shown previously. It
ROOFING SYSTEM SURFACE TYPE RELATIVE SCORE
DURABILITY
Built-up (3- or 4-ply) Gravel High 10
Modified bitumen (2-ply) Granules Moderate to high 9
Single-ply (TPO, heat-welded PVC) Unsurfaced/exposed membrane Low to moderate 8
Single-ply (EPDM, adhered) Unsurfaced/exposed membrane Low to moderate 7
Metal (standing-seam) Fluoropolymer paint High 10
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NO V E M B E R 2008 I N T E R FA C E • 1 7
Table 4 – Durability scoring
should be noted that scoring the age factor
is based purely on the numerical age of the
roof compared to its EUL, while scoring the
durability factor is related more to the relative
durability of one material to another.
USING THE FACTORS
Based upon the evaluations performed
at a multibuilding complex in the north –
eastern-Atlantic region, each roof was given
a ranking score in the categories as defined
above. The scores were determined by minimally
trained field personnel and compared
to the opinions of two Registered Roof
Consultants (RRCs) who had also accessed
each roof. Table 5 summarizes the scores
for selected buildings at the complex to provide
an idea of how the system works. Table
6 summarizes the resultant scores for the
selected roofs and ranks them in order of
priority. It should be noted that the complex
surveyed consisted of approximately 130
buildings, with a total gross building area of
approximately 1.4 million sq ft. In this
phase of the work, 30 buildings were surveyed,
totaling approximately 512,000 sq ft
in area, or an approximate 33% sampling.
Typically, scores below 60 would be considered
a priority for replacement, while
scores above 80 would indicate roofs that
were recently installed or were in good condition.
As can be seen from this ranking,
the complex has many systems that score
between 50 and 70, indicating a great need
at the facility both for maintenance activities
to keep the roofs from deteriorating further
and for funding to begin to replace
those with scores below 50, which indicates
a system that is on the verge of failure.
SUMMARY
In summary, these ten items can be
subjectively rated by minimally trained
individuals to obtain a roof rating. This rating
can then be tracked in a database to
obtain information on the relative degradation
of the roof, and from this information,
projected deterioration rates and replacement
time frames can be determined. In
addition, the rating can be used to rank
multiple roofs across one or more multibuilding
complexes in order to more efficiently
spend limited budgets.
KEYWORDS
Durability, Management Program, Prior –
iti zation, Roof.
REFERENCES
1 Walter J. Rossiter, W.C. Cullen, and
R.G. Mathey, “Roof Management
Pro grams,” NBS Report 85-3239,
U.S. National Bureau of Standards
(now NIST), Gaithersburg, MD,
Novem ber 1985.
2 D.M. Firman, “Maintenance Needs:
An Owner’s Perspective,” 9th Con –
ference on Roofing Technology, U.S.
National Roofing Contractors Asso –
ciation Rosemont, IL, May 1989,
pp.15-19.
3 D. Bradford, “An Industry Perspec –
tive on Roof Maintenance,” Proceed –
ings from Sustainable Workshop on
Low-Slope Roofing, Conf-9610200,
Oak Ridge National Laboratory, Oak
Ridge, TN, October 1996, pp.77-81.
4 D. Bradford, “Roof Maintenance:
BLDG. AGE CRIT. MEM. FLASH. ATTACH. SLOPE/ CONST. LEAKS SUSCEP. DURA.
LETTER DRAINAGE
A 1 3 1 3 8 10 8 6 10 10
B 5 3 8 8 9 8 8 4 10 7
C 1 4 5 5 6 10 10 9 10 10
D 1 4 5 4 6 10 9 7 10 10
18 • I N T E R FA C E NO V E M B E R 2008
Table 5 – Sample individual roof ranking scores
Note: Generic buildings considered to show how rankings would be tallied. Does not match those in Table 6.
What Building Owners Need to
Know,” Professional Roofing, April
2004, pp. 24-27.
5 “Roof Systems Management,” Air
Force Instruction (AFI) 32-1051, U.S.
Air Force, AFCESA/ENC, March
1989.
6 Ibid.
7 Built-Up Roof Management Pro –
gram, Air Force Manual AFM 91-36,
U.S. Department of the Air Force,
September 3, 1980.
8 Rossiter et al.
9 D.M. Bailey, D.E. Brotherson, and
W. Tobiasson, “ROOFER: A Manage –
ment Tool for Maintaining Built-Up
Roofs,” Proceedings from 9th Con fer –
ence on Roofing Technology, U.S.
National Roofing Contractors Asso –
ciation, Rosemont, IL, May 1989,
pp. 6-10.
10 M. Sinderman, “Staying on Top
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. Calculate the moisture content
of mineral aggregate being used
in a built-up roof project.
Samples have been taken and
tested with the following
information determined:
Mass of container (A) = 80 gm
Original mass of sample and
container (B) = 594.8 gm
Mass of sample and container
after drying (C) = 586.2 gm
What is the moisture content of
the aggregate?
2. If the vapor pressure at room
temperature is known to be
0.7392 in Hg (saturated, 100%
RH) and the relative humidity is
to be maintained at 65%, what is
the vapor pressure when air is
saturated (100% RH/dew point
temperature)?
3. The equiviscous temperature
(EVT) is noted on a carton of
asphalt to be 213 degrees
Celsius. What would the
recommended application
temperature be for the BUR?
4. A roof is ponded with 4 inches of
water due to plugged drains and
a severe rainstorm. How much
weight is this adding to the roof
deck?
5. A geographic area has an average
annual exterior temperature of
45˚F. The standard for the area is
HDD 65. How many heating
degree days would each day at
45˚F represent?
Answers on page 20
BUILDING ROOF WHEN ROOF RANKING
NUMBER SIZE BUILT TYPE SCORE
1 107300 1988 EPDM 42
2 5640 1991 EPDM 44
3 5640 1991 EPDM 44
4 5640 1991 EPDM 45
5 5640 1991 EPDM 45
6 5640 1991 EPDM 48
7 5640 1991 EPDM 49
8 5640 1991 EPDM 49
9 5640 1991 EPDM 50
10 51400 1994 Hypalon 52
11 2350 1940 Metal 52
12 5640 1991 EPDM 53
13 2350 1940 Metal 53
14 2350 1940 Metal 53
15 2350 1940 Metal 53
16 2350 1940 Metal 53
17 5640 1991 EPDM 54
18 2350 1940 Metal 54
19 2350 1940 Metal 54
20 2350 1940 Metal 54
21 51400 1994 Hypalon 55
22 51400 1994 Hypalon 55
23 25185 1987 EPDM 56
24 2350 1940 Metal 56
25 2350 1940 Metal 56
26 51400 1994 Hypalon 58
27 14760 1994 EPDM 59
28 6550 1978 Built-up 60
29 51400 1994 Hypalon 63
30 8515 1979 Built-up 66
31 10270 1956 Built-up 70
32 2680 2002 EPDM 70
NO V E M B E R 2008 I N T E R FA C E • 1 9
Table 6 – Roof prioritization.
FAIR CONDITION WATCH LIST NEEDS REPLACEMENT
of the Roofing Business,”
Re tail Traffic, August 2000,
www.retailtrafficmag.com/mag
/retail_staying_top_roofing/.
11 “Roof Systems Management,” op. cit.
12 Bailey, op. cit.
13 Carl G. Cash, “The Relative Dura –
bility of Low-Slope Roofing,” Pro –
ceed ings of the Fourth International
Symposium on Roofing Technology,
National Roofing Contractors Asso –
ciation, Rosemont, IL, September
1997.
14 K.G. Schneider, Jr. and A.S. Keenan,
“A Documented Historical Perfor –
mance of Roofing Assemblies in the
United States, 1975-1996,” Proceed –
ings of the Fourth International
Symposium on Roofing Technology,
U.S. National Roofing Contractors
Association, Rosemont, IL, Sep –
tember 1997, pp. 132-137.
Answers to questions from page 19:
1. 1.70%
2. 0.4805 in Hg
3. 390˚F to 440˚F
4. 21 PSF
5. 20
References:
ASTM D-1684, NRCA Roofing
and Waterproofing Manual,
3rd Edition
ASHRAE Handbook — Water
density
20 • I N T E R FA C E NO V E M B E R 2008
Steve Bentz is a registered professional engineer in five states
and the District of Columbia and a Registered Roof
Consultant. He has been involved in over 100 projects with
Facility Engineering Associates, PC (FEA), including in-field
investigation, testing, and evaluation; preparation of construction
documents; bidding; construction administration of
roof replacement; façade repair; and historic rehabilitation
projects. He is currently a project manager specializing in
building envelope repair and assessment at the Fairfax, VA,
office of FEA.
Steven P. Bentz
Walter Rossiter retired in 2006 from the National Institute of
Standards and Technology, where he was a research chemist
with the Building and Fire Research Laboratory with over 35
years experience in the performance of organic building materials.
In this position, he directed numerous studies on the
characterization and performance of roofing materials and
systems. Walt joined RCI, Inc. in 2007 as its director of technical
services. He is a past chairman of ASTM Committee D08
on Roofing and Waterproofing, and past chairman of the Joint
International CIB/RILEM Committee on Membrane Roofing Systems.
Walter J. Rossiter
The Center for Environmental Innovation in Roofing, an arm of the National Roofing
Contractors Association, has announced a call for entries for its Excellence in Design
Award, which honors those who design energy-efficient, environmentally friendly, and
long-lasting roof systems. Architects, specifiers, roof consultants, and roofing contractors
who are responsible for a nominated roof system’s design are eligible for the competition.
Entries must be postmarked by November 21. The winner will receive a $2,500
cash prize and acknowledgment in Professional Roofing and on the NRCA Web site.
For more information, visit www.specright.net or e-mail mary@roofingcenter.org.
DESIGN AWARD ENTRIES SOUGHT