Roofing Trends

Since the turn of the century,
there have been many changes
in the low-slope roofing industry.
What has occurred? What
is causing it? How has the roofing
industry responded? What
are the driving factors? And what is causing
the roofing industry to transform so dramatically?
There is no smoking gun that can
account for the shift in roofing other than a
confluence of economic, legislative (code),
and environmental issues that are rearranging
the roofing landscape.
GROWTH OF SINGLE-PLIES
In 2000, built-up roofing (BUR) was the
leader of the low-slope roofing market, with
a 45.7% market share.1 Now BUR accounts
for only 6% of the new low-slope construction
roofing market and 9% of the reroofing
market of contractors who are members
of the National Roofing Contractors
Association (NRCA).2 Conversely, thermoplastic
polyolefin (TPO) had an 11.6%3 share
in 2001 and currently commands 40% of
the new low-slope construction market and
30% of the reroofing market among NRCA
members (Figure 1.) The big winner is TPO,
but how and why?
The growth of TPO over the past 15
years was heavily influenced by the dramatic
economic swings of the first decade of this
millennium. We witnessed two momentous
economic downturns sandwiching a dramatic
growth in commercial construction.
Starting in 2003, the real estate market in
the U.S. expanded dramatically. Between
2001 and 2008, there was a huge inflow of
capital into real estate (Figure 2). All types of
construction were occurring, from homes, to
schools (government), to shopping centers,
Ma r c h 2 0 1 7 I n t e r f a c e • 1 9
Figure 1 – Product mix of new low-slope construction sales by roof system of contractor
members of the NRCA, 2016.
to mega warehouses. The government sector
predominately continued utilizing asphaltbased
systems, whereas the commercial
real estate sector, which was focused on
return on investment (ROI), looked towards
other roofing systems to lower their cost of
construction.
During this construction boom, there
was a huge demand for skilled laborers
throughout the construction industry.
Because of the growth in construction,
demand for qualified, trained tradesmen
outstripped the roofing industry’s ability
to supply. The shortage of skilled roofers,
therefore, became a major problem.
Asphalt-based systems require the contractor
to install multiple layers (plies) of
roofing to build the roof. Single-plies, as
their name suggests, require only one ply
of roofing material. Therefore, much less
labor per square foot is required to install a
single-ply system than an asphalt system.4
The redundancy that is inherent in a BUR
or modified system was not as valued to the
commercial real estate industry as was the
ROI. Because of the economic boom, the low
unemployment rate, and the need for higher
ROIs, single-ply roofing systems—and, particularly,
TPO—became the roofing systems
in highest demand.
LONGER WARRANTIES
In 2008, just as the economic crisis
started to dramatically impact the construction
industry, a shift was occurring with the
length of roof warranties and the gauge of
the membranes. Prior to 2008, the majority
of TPOs installed were 45-mil; but in 2008,
that balance shifted to 60-mil membranes.5
The average length of TPO roof warranties
prior to 2008 was around 12 years.
Now TPO warranties are averaging over 17
years.6 Many TPO manufacturers only provided
warranties in excess of 15 years with
60-mil or thicker membranes. Commercial
real estate building owners were demanding
longer-term roof warranties. Buildings without
roof warranties were being discounted
by the buyer. Often lending institutions
would not even provide financing unless the
building had a roof warranty.
Longer roof warranties allow the building
owner a greater window in which to
divest the building without being penalized
at the sale. Owners that are long-term
holders of the buildings understood the
benefits of thicker membranes and longer
warranties. There is a clear demand by the
customer and a willingness by the manufacturers
to increase the length of roof warranties.
These thicker membrane products last
longer and are less susceptible to incidental
damage, which is good for the manufacturer
and the building owner.
HD COVERBOARDS
High-density (HD) polyisocyanurate
boards have become popular within the past
ten years. Their light weight, ease of handling,
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Figure 2 – Commercial real estate transaction volume. Source: Real Capital Analytics.
Figure 3 – Induction welding.
Figure 4 – Solar reflectance and thermal emittance. Source: Cool Roof Rating
Council.
and speed of installation compared to some
other cover boards are attractive qualities.
These characteristics give them an economic
advantage over traditional cover boards in
regard to installation costs. Gypsum-based
cover boards are heavy, difficult to cut, and
susceptible to degradation when wet.
Manufacturers design the new HD boards
to meet many of the characteristics of previous
cover boards but without their negative
attributes. These boards come with closedcell
insulation and glass-coated fabric facers,
therefore avoiding potential mold issues. On
the downside, they do not have the same
compressive strength of the gypsum-based
materials, but can be more durable than
other coverboards. HD boards have compressive
strength between 80 and 125 psi, whereas
gypsum-based cover boards can achieve
compressive strengths of 800 psi.
INDUCTION WELDING OF
THERMOPLASTICS
Another innovation that is gaining in
popularity is induction welding of thermoplastics.
Induction welding is the use of
an electromechanical field to heat a bonding
plate located under the thermoplastic
membrane and to weld it to the membrane
(Figure 3). This is considered a nonpenetrating
attachment method. From an economic
and labor standpoint, contractors would like
to use the widest single-ply sheet possible
when installing mechanically attached systems.
This reduces the amount of seams,
fasteners, and labor required to complete the
roof. However, in order to meet certain uplift
requirements, the spacing of the fastener
may preclude the contractor from using
the widest sheets available. With induction
welding, the attachment of the membrane
is accomplished across the entire sheet, not
just at the membrane’s edge. This distributes
the uplift forces over more structural
members, allowing it to withstand greater
uplift pressures. Consequently, a contractor
can use wider sheets, fewer fasteners, and
less labor and still meet the design pressures
for the roof. These productivity gains
and cost reductions are of particular interest
to building owners and roofing contractors.
As a case in point, a building owner
recently shared bids regarding a new
750,000-sq.-ft. warehouse. The contractor
quoted installing a 60-mil induction welded
system for the same cost as a 45-mil
mechanically attached system. The reduced
labor associated in installing an induction-
welded system allowed the owner to
opt for a thicker membrane roof, which the
building owner found as a great value.
REFLECTIVITY
Another factor driving thermoplastic
growth is the “green” movement. Global
warming or climate change has become a
focus point for many individuals and governments.
Electrical blackouts caused by
the increased use of air conditioning (AC)
had people looking at ways to reduce the
electrical demand and carbon footprint of a
building. A relatively easy and passive way
to reduce the AC demand was to design
roofs that reflected the solar heat away
from the building; thus, reflective and emissive
requirements and codes were created.
Solar reflectance is the fraction of solar
energy that is reflected by the roof. Thermal
emitance is the relative ability of the roof
surface to radiate absorbed heat (Figure 4).
In 2005, California adopted building
energy efficiency standards that required
“cool roofs” on low-slope, nonresidential
roofs as part of the already-existing Title 24.
Around the same time, Chicago, Illinois,
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mandated cool roofs. Additionally, the U.S.
Green Building Council (USGBC) created the
Leadership in Energy and Environmental
Design (LEED) certification program for
buildings that are designed, constructed,
and operated towards sustainability. This
program assigns points for certain types
of designs and provides a construction
point for white roofs. Many designers and
building owners determined that one of the
easiest and least expensive ways to achieve
credit toward LEED ratings or comply with
the standards was through installation of
a TPO or PVC roof. Though PVC and TPO
come in many colors, by far the most prevalent
color is white. The chart in Figure 5
shows the various codes and requirements.
Different modified bitumen (modbit)
manufacturers created white cap sheets
to meet code requirements and market
demand. There are many applications where
a modbit system is a better roofing system
choice. Manufacturers have created
modbits using white granules, synthetic
chips, trilaminate films, and acrylic coatings.
These modbit cap sheets are required
to pass Energy Star, Title 24, and LEED
requirements if they are expected to be
used where the code requires reflectivity.
Modbit systems have an important place in
the roofing industry but are commanding
a shrinking portion of the roofing market
because of their higher installed cost compared
to single plies.
INSULATION
While the green movement influenced
the color of the roof, it also influenced the
codes relating to building insulation. Codes
for continuous roofing insulation above
the deck have dramatically increased the
amount of insulation required. The table in
Figure 6 demonstrates the increase in insulation
required by the ASHRAE 90.1 codes.
Between ASHRAE 90.1-2004 and ASHRAE
90.1-2013, the required insulation has doubled
in some zones in less than a decade.
This increase impacts the installed cost, but
it should decrease the overall operational
energy cost of a facility.
ADHESIVES
New adhesives have been created over
the past decade to adhere these new singleply
products. With many hot kettles collecting
rust in the warehouse yard, other
nonpenetrating attachment methods were
needed. There are several markets throughout
the U.S. that prohibit high volatile
organic compound (VOC) adhesives (Figure
7). To address this, manufacturers have
developed low-VOC and water-based adhesives,
as well as self-adhered membranes.
These products are designed to be used
anywhere there are low-VOC requirements.
These products may be used where regulatory
requirements limit or exclude the use
of solvent-based adhesives, but most are
constrained or impacted by low temperatures
and high humidity. These products
usually take longer to install, if they can be
installed at all at low temperatures. Some
manufacturers have created adhesives and
self-adhering membranes that have great
2 2 • I n t e r f a c e Ma r c h 2 0 1 7
Figure 5 – Reflectivity requirements.
Figure 6 – ASHRAE R-factors.
Figure 7 – VOC restriction areas in the U.S.
temperature installation parameters and
can increase the productivity of the roofer.7
SOLAR
Solar projects in the United States have
grown at a compounded annual rate of over
60% for the last ten years. This growth has
occurred as the installed price of solar has
decreased 70% over the same time period.
Solar adoption has not been uniform across
the U.S. This is evident with California having
close to 50% of the U.S. solar generation
(Figure 8). Whatever the reason for solar
being adopted, many of these systems are
being installed on commercial roofs.
There are two types of systems being
installed: “thin film” and “crystalline.” They
are being installed through penetrating
mounting systems (crystalline), ballasted
nonpenetrating systems (crystalline), and
self-adhered or bonded systems (thin film).
Solar energy generates “clean electricity” for
the building owner or utility provider. It is
not a product that protects the occupants of
the facility from the weather. Most roofing
manufacturers have policies regarding the
installation and maintenance of solar over
their membranes. Some roofing manufacturers
have dedicated teams to assist building
owners with their solar projects.
There have been numerous articles published
in RCI Interface addressing solar
collectors. A search on “solar” in the RCI
Technical Articles Library (http://rci-online.
org/publications/tech-library/) returns
179 results, which shows that solar is a
very hot subject. With the declining prices
of solar installations and companies
focused on their “carbon footprint,” solar
projects will continue to cover many more
roofs.
VEGETATIVE
Another trend tied to the green movement
is the increased use of vegetative
roofs. Vegetative roofs (Figure 9) have been
installed in the U.S. since the 1970s, but
have seen limited use until recently. But
now vegetative roofs are being installed in
locations where the municipalities are mandating
a reduction in stormwater runoff.
The soil and plant materials on vegetative
Figure 8 – Cumulative solar photovoltaic (PV) capacity through Q2 2016. Source: SEIA.
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roofs absorb rainwater during storms and
release it into the environment at a slower
or indirect way, thereby reducing the
quantity of water being discharged into the
storm system.8 This is important because
in older cities, the stormwater and sewage
systems are often combined. During heavy
downpours, these systems are taxed beyond
their ability to safely move sewage to the
treatment plants, and untreated sewage
gets dumped into our waterways.
Another advantage to vegetative roofs is
their ability to create micro-environments.9
They can reduce the temperature within
the building, create environments where
wildlife can grow, and develop places where
the local occupants can enjoy the outdoors.
Vegetative roofing systems are classified
into three systems: extensive, semiintensive,
and intensive. Extensive systems
are the most common. These systems can
be designed to meet the specific stormwater
control, weight, and cost parameters for the
project. They are usually the least expensive
and lightest of the three, which makes
their adoption easier. Intensive systems use
the most growing media and are often built
in place. These are intended to be used as
amenity spaces for the occupants of the
building. The semi-intensive falls between
these two systems. Whatever system is
used, the building owner will need to understand
the engineering and waterproofing
requirements to make the system perform
and last.
DAYLIGHTING
Daylighting has been around since the
beginning of civilization. Prior to the advent
of electricity, people were always trying
to get sunlight into interior spaces. Once
Thomas Edison created the lightbulb, the
need for natural light inside a building
became less necessary. Buildings could be
built that were hundreds or even thousands
of feet deep without any natural lighting.
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Figure 9 – Vegetative roof system.
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ASHRAE 90.110 mandated the use
of natural light in commercial buildings
through skylights or windows. This mandate
was created to reduce the use of electricity
and a building’s carbon footprint. In
some instances, the amount of electricity
consumed by a building can be reduced by
35-60%11 with the addition of a daylighting
system.
In many buildings, getting the required
light to an interior space can only be
achieved through skylights. Often these
skylights are used along with an active
daylighting system (Figure 10). These systems
monitor the amount of daylight that
is coming into a building and automatically
turn the interior lights on and off. With
more facilities being built with skylights and
daylighting systems, more waterproofing
and flashing concerns will be associated
with them.
CONCLUSION
What are the new roofing trends and
products going to be? I do not have a crystal
ball, but some of the items that influenced
the past ten years in roofing will be the
same influencers for the next ten years.
Finding qualified employees, environmental
concerns, government mandates, codes,
laws, and how to address these items to
deliver the best value for the end customer
will be issues facing the roofing community
into the future.
REFERENCES
1. Ashley St. John. “In With the New.”
Professional Roofing. July 2011.
2. NRCA Annual Report, 2015-
16, Membership. www.nrca.net/
Membership-1516.
3. Stephen A. Sharp. “TPOs – Commodity
or Speciality?” Professional Roofing.
June 2002.
4. Dick Fricklas. “Single-Ply Roofing –
Half a Century of Experience, but
What Have We Learned?” Interface,
August 2007.
5. Major TPO roofing manufacturers.
6. Major TPO roofing manufacturers.
7. Vincent Hill. “A revisit of Self-
Adhered Roofing Materials.” Interface,
November 2016.
8. Green Roofs for Healthy Cities.
greenroof.org.
9. Green Roofs for Healthy Cities.
greenroof.org.
10. Energy Standard for Buildings Except
Low-Rise Residential Buildings.
11. B. Atkinson, A. Wilson, K. Garbesi,
and F. Rubinstein. “A Meta-Analysis
of Energy Savings From Lighting
Controls in Commercial Buildings.”
Energy Analysis Department, Lawrence
Berkeley National Laboratory.
September 2011.
Ma r c h 2 0 1 7 I n t e r f a c e • 2 7
Vincent Hill is the
consultant services
manager for
Firestone Building
Products. In his
current position, he
manages Firestone’s
relationships
with the roof
consultant community.
Prior to Firestone,
his 30-year
career involved
managing and
overseeing the roofing assets for several
large industrial REITs.
Vincent Hill
Figure 10 – Skylights/daylights.
RCI recently received exciting news for building envelope consultants.
In early January, the United States Census Bureau released 2017 NAICS,
the latest update of the North American Industry Classification System
(NAICS). This 2017 version now cites building envelope consulting services,
roof consulting services, and waterproof [sic] consulting services within
Classification 541690, titled “Other Scientific and Technical Consulting
Services.” RCI members and others engaged in building envelope consulting,
when asked to provide a “NAICS number,” can now pencil in “541690.”
For an extensive article on the process RCI went through to obtain the
NAICS index item classification for building envelope consulting and its uses
in business, visit the newsfeed at rci-online.org.
Building Envelope Consulting
Achieves NAICS Recognition