Texas A&M Study
A COMPARISON OF CONVENTIAL AND SPF ROOFING SYSTEMS
Sam Cohen
Project Management Supervisor
Engineering Design Services
Physical Plant Department
Texas A&M University
In 1974, dissatisfied with
performance of traditional tar and gravel built-up roofing (BUR) systems, the
Physical Plant Department began looking for viable roofing alternatives. The BUR
roofs were constantly leaking, and because of the nature of BUR, leak detection
was virtually impossible.
As the Physical Plant
Department began soliciting information from various roofing sources and
checking references, sprayed polyurethane foam (SPF) roofs exhibited advantages
that seemed to fit the criteria of the University. The Physical Plant Department
found the following:
- Seams are one of the
major sources of leaks in roof systems and SPF roofs are totally seamless.
- Water does not travel
laterally in SPF roofs as it can in BUR or single-ply roofs. A leaks in the
top membrane of a BUR or single-ply roof will create the spreading of water,
saturating the insulation and causing multiple interior leaks. With SPF,
even if a hole is punched through the entire two-inch membrane, water
movement will be restricted to the hole. In most cases repairs can be made
with a tube of caulk.
- Because the SPF roof
is lightweight, permeable and fully adhered, normally an old roof does not
need to be removed in order to apply a new one. If underlying areas of
saturated insulation are found, minimal tear-off may be required.
- The SPF roofing is
less disruptive to students and faculty since tear-off is minimal. Also,
projects are accomplished faster because the application is quieter, quicker
and requires far less laborers.
- Roof mounted units,
penetrations, curbs, and parapets can receive a seamless monolithic
application because SPF is spray applied. BUR and single-ply roofs require
flashing materials with sealants which frequently result in leaks.
In 1974-75, convinced the
proceeding advantages warranted taking a look at this relatively new roofing
system, the Physical Plant Department issued contracts for the reroofing of
several buildings. One of the earliest roofs done with this system was
Davis-Gary dorm. After seventeen years this roof has not leaked and requires
minimal maintenance.
Between 1975 and 1977 the
Physical Plant Department and TAMU Systems Facilities Planning and Construction
(FPC) communicated back and forth concerning the monitoring of these roof
installations. New BUR roofs were providing the University with service life of
less than five years, and many of the BURs were leaking from the onset. In 1977
the Physical Plant Department foamed over a BUR application that was less than
four years old. After monitoring the SPF installations, FPC was also convinced
and since 1977, all new roof applications have used SPF roofs.
FPC received numerous
complaints stemming from this decision. Few roofing contractors had the
financial ability to mobilize spraying foam. Fewer still had the caliber of
crews that chemically formulate foam in the field. Though this eliminated
potential bidders, it in effect greatly elevated the caliber of roofing
contractor performing work at Texas A&M.
Many outside architects
working at the University were unfamiliar with the system, and some of these had
a reluctance to learn anything new, but the Physical Plant and FPC were adamant.
As time went by, architects and general contractors learned the many advantages
of the system. This caused proliferation of the SPF Roof systems in surrounding
school districts and Universities.
Today over 7 million
square feet of SPF roofing has been applied throughout the A&M system. With very
few exceptions, these roofs are holding up extremely well. In fact, it is
extremely rare that one of these roofs leaks at all. Blister defects, which
occasionally occur, do not create leak problems. Most leak problems at our
campus occur on the few buildings that still have BUR on them.
In 1985 the Physical Plant
Department found another advantage in using SPF roofing systems. For a number of
years, Mr. Gerald Scott, P.E. was in charge of roofing and energy conservation
within the Physical Plant Department. Vendors of the SPF system always
championed the energy saving characteristics of the system. We realized
polyurethane was a most effective insulation, but our main concern had always
been to prevent roof leaks.
Mr. Scott monitored energy
savings on 27 different buildings that had received SPF roofs from 1980 to 1984.
The results were astounding. TAMU was able to recover the complete cost of the
roof application through energy savings in an average of four and one-half
years.
Quoted here is Mr. Scott’s
conclusion, which is still shared by today’s Physical Plant Department:
From the time of
construction, and throughout the life of the roof, built-up roofs were major
maintenance and repair items. The experience that the Texas A&M University
Physical Plant gained since 1974, when they began, indicates that no major
problem, and very few minor ones exist in the polyurethane roof systems. As a
result of this experience, all new construction includes the foamed polyurethane
roof system. To date some 16 new facilities have this roof system totaling
nearly one million square feet.
Another major advantage in
a SPF roof system that does not exist with any other roofing system, is that SPF
is a renewable system. While BURs and singly-plys must be removed and replaced
after their usable lives, SPF roofs can be repaired and recoated to offer an
indefinite life expectancy. Coupled with the energy savings and reduction in
in-house maintenance costs, the SPF roofing system maintains a tremendous
long-term cost efficiency advantage over all other roofing systems. Without
question SPF roofs have a tremendous edge in preventing leaks and in detection
and repair when one does occur.
The conclusion of today’s
Physical Plant Department has not varied from the conclusion reached by Gerald
Scott in 1985. We at the Physical Plant Department continue to monitor the
progress of other roofing systems available. But at this time, no other roofing
system can offer the leak free service, the ease of leak detection and
maintenance, the energy efficiency, durability, or renewability provided by
sprayed polyurethane foam roofs.
