Figure 1: Clay-tile roof from Ludowici Roof Tile, Inc., a division of CertainTeed Corp.
Of all the common materials used in construction, none poses quite the challenges of roofing—particularly from an environmental standpoint.
Roofs provide one of the most fundamental functions of a building: shelter from the elements. Roofs must endure drastic temperature swings, long-term exposure to ultraviolet (UV) light, high winds, and extreme precipitation. Yet much of the roofing industry is driven by highly competitive economics and thin profit margins that conflict with these performance and durability requirements. As a result, roofs commonly exhibit the lowest durability of any major building component except carpeting, requiring and frequent replacement. The National Roofing Contractors Association (NRCA) estimates that 78% of the dollars spent on roofing in the U.S. are for
roofing, as opposed to roofs on new buildings.
Given the enormous ongoing investment of resources, energy, and dollars in resurfacing worn-out roofs, any measures that will increase a roof’s longevity are environmentally desirable. Aside from simply investing in better (and usually more expensive) materials, there are some specific regional and climatic considerations that can affect product durability. For example, some products may stand up well to intense heat and ultraviolet radiation from sunlight, but succumb quickly to repeated freeze-thaw cycles. A product’s resistance to natural hazards such as hurricanes, hail, and fire must be taken into account where appropriate. Finally, a roofing surface is only the most visible part of a complete roofing system, and the system is only as good as its weakest link. Thus, flashing details should be designed with the longevity of the roofing material in mind, accommodating any foreseeable maintenance requirements.