News and Events

Is Your Roof Upside Down?

posted 01.22.2014

A New Roof Solution

Terracon is built on the principles of being responsive, resourceful, and reliable. We strive to provide quality service to our clients and work to generate innovative solutions for their needs. When a client has certain expectations for a project, our goal is to say, “Yes, we can do that for you.” But, sometimes telling a client “no” is in their best interest.

Shriners Hospitals for Children (Shriners) has retained Terracon’s Facilities Services for many roof replacement projects over the last 13 years. We have cultivated a great understanding of the type of roof system that they expect.

Shriners has traditionally desired an SBS-modified bitumen roof system, primarily for both cost effectiveness and durability, on low-sloped roofs and shingles on steep-sloped roofs to replace the existing roofs of similar type. Much to our surprise, when we arrived on site at their Tampa hospital, we discovered an inverted roof membrane assembly (IRMA). An IRMA is essentially “upside-down” in comparison to a conventional low-sloped roof system. Traditionally, the roof membrane covers the insulation in the roof system, but with an IRMA, the membrane is applied directly to the deck and the insulation is overlaid on the membrane, usually in the form of composite roof pavers.

Shriners Roof Image

As we conducted our field investigation, we learned that the existing roof system had caused the facility extensive leaking problems. Based on our knowledge of industry standards for membrane flashing heights at parapet walls and equipment curbs and requirements for insulation thicknesses to meet specific R-values in that climate zone, we suspected the roof structure dimensions and the placement of the existing roof drains and roof top equipment would not readily allow us to replace the roof with Shriners’ preferred SBS-modified bitumen roof system. Our field investigation confirmed those suspicions.

We researched alternative roof systems that could meet or exceed the requirements of the building code, decrease energy costs, and eliminate leaks. We found that, due to the original design and construction of the facility, we would need to design an IRMA similar to the existing system. Shriners was less than thrilled when we delivered the news that our proposed roof design would resemble their current roof system which had been so problematic. They reiterated their desire for a roof system similar to the others we had designed for them over the previous 13 years.

We knew, however, that in the 20 years since the existing IRMA was applied on the hospital, significant advances had been made by manufacturers to this FM Global approved assembly. Two of the most beneficial improvements included the substitution of a polyvinyl chloride (PVC) roof membrane, for the now obsolete rubberized asphalt and polyethylene composite membrane, and the addition of a geotextile drainage mat that would prevent ponding under the composite roof pavers. We also generated a rough estimate of utility cost savings that could be realized through the IRMA’s allowance of increased insulation thicknesses above the roof membrane that a traditional roof could not accommodate due to the slope requirements of those systems. Only through illustrating the enhancements to the system and emphasizing the cost savings they would achieve with those enhancements could we successfully tell a client, “no” for their benefit.

Due to Terracon’s successful, long-term working-relationship with Shriners, we had the knowledge and expertise to achieve the desired result (a new, efficient roof) by implementing a solution that had not been a part of their original vision. The leaks were gone and the hospital realized a significant cost savings on their utilities.

The IRMA system installed at the Shriners Hospital for Children in Tampa continues to provide the client a patio-like roof top surface and will continue to perform and protect the roof membrane from physical and ultraviolet damage throughout its service-life and most likely, well beyond.