In 2007, a lot of attention is being given to sustainable design in building construction. This is a very good development for the roofing industry and for our customers. The commercial roofing market is now, perhaps more than ever, sensitive to the total cost of ownership of a roof system. This total cost includes not only the life-cycle cost of the roof system, but also the cost of its ultimate removal and disposal. These costs are real and they vary widely depending on the choice of materials and system design.

In recent years, designers have increasingly used tapered roof insulation products to build slope into the roof systems. Sustainable design calls this practice into question. Building slope into the permanent structural components of the roof, instead of the disposable roof insulation, means lower overall cost to the owner and much lower waste when the roof is replaced. As a result of sustainable design principles, we are beginning to see a return to structural design where slope is integral to the roof structure.

Sustainable design encourages modularity in roof construction, where possible. That is, whenever the roof membrane can be replaced without replacing the underlying insulation, the cost of ownership of the roof is reduced, and the amount of waste produced at roof replacement is reduced – a win-win for everyone! Often, careful roof design and materials selection can offer this benefit without a sacrifice in performance or cost.

Perhaps “green roofing” is the hottest topic in sustainable design concepts. Green roofing, as commonly discussed, is the transformation of roof areas into vegetative areas. This transformation is no small matter! Many serious technical factors must be taken into account when considering a “green roof”. These factors include: increased structural loads, proper plant selection, fire resistance ratings, and wind resistance ratings, to name a few.

Another consideration in deciding on a green roof is the performance of the underlying roof system. Many roof materials are not suitable for long-term performance under a vegetative cover. Constant exposure to moisture and root penetration make most conventional roof systems poor candidates for use in green roof designs. Savvy designers and buyers know systems that have stood the test of time are the best choices when reliable performance is required. Covering a roof system with vegetative cover can hike the cost of roof replacement by 400-500%, so long term performance of the roof membrane system becomes a critical factor in the success of a green roof design. Perhaps the conventional 20-year life expectancy is too low for the green roof installation to make economic and practical sense.

Today, most roofing manufacturers are rushing to market with “green roof” specifications and marketing plans. Also, typical in American business, these new specifications come with long term guarantees. Surely, by now we know that the warranties are written as marketing tools for businesses. They are not based on real performance expectations. A green roof is no place to pin your hopes of long-term performance on a guarantee! Instead, do the research, ask around, and look for time-proven solutions.

Sustainable design calls for all of us to consider the long-term effects of our decisions, and that’s a good thing!