Better Roofs Are Less
Expensive
Article by Richard
A. Boon, P.E., CCI
The ultimate question for roofing
is: “What is the best roof?” The
accountants will tell you that the
answer is simple: It is the roof
that costs the least over its life.
It really does not matter what
material is used or how the roof is
attached; the answer is the same. If
the roof fails, then the cost of a
new roof is added to the cost.
When most owners look at
roofing, they look at the
materials and the systems, and the
only part of the cost they consider
is the initial cost. But the cost to
install a roof is only a portion of
the total cost of owning a roof.
The practice of examining the cost
of owning a roof over its entire
life is called life-cycle cost
analysis. This is the best way to
truly compare the cost/value of
roofing systems. Something that is
crucial is: How long do you expect
to own the building? If the answer
is indefinitely, then the analysis
should be run for at least 20 years.
Some people will use 30 years. The
standard depreciation for roofing is
39 years. There are very few systems
that are functional at the end of
this life expectancy.
In a basic life-cycle cost analysis,
there are several factors that need
to be considered. The study period
has already been mentioned. The next
consideration is the changing value
of a dollar over time. One common
method for relating future expenses
to today's costs is to use the
t-bill rate, minus the inflation
rate. A time value of approximately
5 percent is a reasonable number for
use in our analysis.
There are costs associated with
other aspects of roofing, such as
installation inspections,
semi-annual inspections, the cost of
leak-related repairs, costs
associated with making the warrantor
live up to the warranty, and so on.
There are also routine maintenance
expenses to consider, such as
cleaning the drains, recaulking the
flashings and performing general
housekeeping.
With some systems, the costs of
performing some of these items are
covered by the warrantor as a part
of a comprehensive service package.
They can also be purchased from some
contractors or roofing consultants
for an annual service charge. All of
these costs need to be known or
estimated for the term of the study
period.
The last item that needs to be known
is the relative life expectancy of
the roofs in question. There are
sources for this information. The
most conservative approach is to use
the warranty life as the service
life. This is generally shorter than
the real life, except where there is
no routine maintenance done. Then
the life may well be shorter than
the warranty.
Life-cycle Cost Scenario
Let's create a simple scenario that
illustrates how these factors
combine to produce a life-cycle
cost:
The roof in question is bid using
two different systems. The first is
a commodity-grade roof with a
15-year warranty; the bid is
$225,000. The second system is a
premium roof, and the bid is
$300,000.
We are assuming that the owner is a
public entity, so that taxes can be
ignored. We are using our 5 percent
for the time value of the funds.
The cost to maintain the
commodity-grade roof is at least
$1,000 per year, to cover the costs
of the required inspections for
warranty and the cost of a
consultant on the project during
installation (many consultants are
considerably higher).
When that roof is replaced, in its
15th year, its present value cost is
$113,640, representing the initial
cost adjusted by the time value of
the funds. When you add the
continuing cost of maintenance, the
total-ownership cost for the
commodity roof becomes $354,781.
With the second system, assuming
that the premium roof is replaced in
its 24th year, the present value
cost is only $97,671. Since the
system supplier provides the
required inspections as a free
service, there are no
maintenance-related costs for the
first 15 years of the roof. Let's
assume as much as $1,500 in annual
maintenance from years 15 through
23. Let's also assume roof
replacement in year 24, a
conservative estimate for a roof
that was warranted for 20 years.
Even with these conservative
estimates, the total-ownership cost
for the premium roof is $346,273. As
the federal interest rates drop, the
difference in total-ownership cost
increases, making the premium roof
an even better buy.
Since the premium roof has a
manufacturer's rep on site during
installation, installation-related
problems and add-on inspection costs
are minimized. In addition, on-site
manufacturer observation provides
the benefit of single-source
liability, should problems
eventually occur.
The figures used in this
illustration are in accordance with
ASTM E-917, Standard Practice for
Measuring Life-Cycle Costs of
Buildings and Building Systems,
which provides building owners with
an excellent tool for comparing
roofing options on a sound financial
basis.
Other Factors
There are other factors that can be
included in a model. These include a
simple energy cost savings as well
as the costs that are associated
with any leaks in the system. If a
roof leaks, then the wet areas need
to be fixed, as does the damage done
inside the building. The additional
energy lost can be considered as
well.
There is also a cost associated with
disrupting the facility to put a new
roof on. This should be added to the
cost of the roof. How much does it
cost to clean up after a leak? This
too, must be added.
It has been reported that the return
on an initial investment of $10 to
$12 can be justified through the
savings of a single dollar per year
in maintenance.
So, which of these roofs saves the
owner the most money? Clearly, the
higher up-front costs of premium
roofing systems can be fully
justified through long-term savings.
By looking at more than just the
initial cost of the roof, the owner
is making a better financial
decision. This same analysis is
useful for making a multitude of
construction-related purchasing
decisions.
Are the published life expectancies
of high-performance roofing products
truly achievable? There is no
question that if someone
knowledgeable looks at the roof at
least once a year (industry
recommendation is twice a year), and
the problem areas are corrected
promptly, most commercial roofs will
last significantly longer than their
warranties. The exception is when
defective materials cause the roof
to shrink excessively or to shatter.
About the Author:
Richard A. Boon, P.E., is an
independent roofing consultant with
Construction Support Services, Inc.
of Littleton, Colorado. He is a past
director of The Roofing Industry
Educational Institute and serves on
Roofing Contractor’s editorial
advisory board.
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company from the Bay to the Central
Valley, please
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Inspection at 800-639-7663 or
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