As a roofing expert, one of the questions I address most frequently from clients is the question of cost. They not only want to know how much a roofing system will cost to purchase and install, but also the lifecycle costs of commercial roofing systems. Indeed, it is important to know the lifecycle cost of a commercial roofing system before committing to it.
I often use the following illustration to give a lifecycle cost comparison. I compare a premium black roof that needs asphalt as adhesive and that will include a white granular surface to a premium white fluid-applied roof that is fully adhered. Still, for purposes of comparison, let us assume that the roofs of 10,000 square feet will be installed in Los Angeles, California. The project is a re-roofing project for a roof that has an asphalt built-up system. Let us also assume that the structure weight limitation is almost at maximum. We will calculate the life cycle cost using a time frame of 20 years, which is the minimum time frame that most building owners expect their roof will last.
Before looking at the variables that are usually considered to calculate the life cycle cost of a roof, let us consider the initial cost of installation. The initial cost of the premium black roof with granular surface is $56,800, while that of the premium white fluid-applied roof is $57,800. It seems that this concludes the comparison, right?
Not so. Without considering the 20-year lifecycle cost to arrive at present value, the comparison is not correctly done. Over the span of 20 years, the premium black roof with a white granular surface will cost approximately $115,220. The premium fluid-applied membrane roof will cost $46,600. This is because of the variables that are used to calculate lifecycle cost.
What are the variables?
Clearly, the initial cost of installing a roof is not the factor that mostly determines the lifecycle cost. Rather, the most dominant factor that determines this cost is the expected lifecycle of a roofing system, considering the environment it is in. This is because if a roof does not last 20 years as expected, the owner will have to incur costs that are higher than average in maintenance as the roof approaches the end of its cycle.
Major renovation costs may also be incurred, or even complete replacement costs. Apart from the initial cost of installation, the cost of maintenance and perhaps major renovation, there are other variables that are factored in to arrive at accurate roof lifecycle costs. Depending on whether they are relevant to a particular situation, these are:
• cost of disposal
• energy savings made from installing a roof with a lighter color
• rebates offered by the city, state or utility company for installing roof systems that are energy-efficient
Expected roof life
Research has shown that the average life of the premium black roof used in the illustration is 13.9 years, while that of the premium white roof is over 20 years. The actual life of a roof varies a lot, depending on environmental conditions. For instance, is the building in an area where UV rays are more intense, such as the South? Is the roof exposed to chemicals emanating from nearby industrial plants? Is the building near an airport where it can be damaged by jet fuel? When doing roof life cycle analyses, it is important to use figures that represent the proven life of the selected roof system as it has been found to perform in buildings in the same locality and environment.
Experts agree that the number of years that should be factored in when calculating the lifecycle cost of a roof is the proven life of a system with the same chemical formulation in the same environment. Nothing can substitute for this, and there are no scientific tests that can accurately predict the life of a roof system in the real world.