Sustainable Roofing Systems – Thinking Outside the Box

A truly sustainable roofing system is an umbrella that not only protects a building from the elements, but seeks to reduce negative impacts on the environment and health of building occupants, thereby improving building performance. To achieve sustainability in roofing replacement projects, conscious choices must be made regarding products and the way in which they are used. While going “green” has become increasingly popular in today’s eco-conscious climate – getting there remains the challenge.

The performance requirements of any roof membrane are exacting. The process of assuming recycled content is more complex than specifying and installing a new roof. Design teams must consider the performance history of the new roofing system, and any constraints imposed by the existing building.

Litigation around roof systems is not uncommon. From aging products, limited warranties to faulty installation, many experts prefer a full-tear-off roof assembly to protect against lawsuits. Installing a new roof makes it easy to control materials and installation from the roof-deck up, but a lot of valuable resources may be discarded with this approach.

THE JONES PAYNE SIGNATURE APPROACH

Jones Payne believes extending the life of existing materials is perhaps the most sustainable feature of any roof replacement project. We evaluate each existing roofing system to see if components can be re-used. Our team’s approach involves stripping the roof membrane (top layer of the roof assembly) to expose the underlying coverboard, and then designing a new roof system utilizing the existing coverboard and roof insulation. 

Most roofing systems include a coverboard under the roofing cap sheet. The coverboard is provided to protect the underlying insulation from impacts and to provide a smooth surface for the roof membrane application. The use of a coverboard is common for both single-ply and built-up roofing systems. Removing the cap sheet in adhered roofing assemblies splits the coverboard in half, creating an ideal substrate to use for a new roof assembly. Our methodology provides decisive advantages. The exposed coverboard reveals moisture issues so that any wet insulation can be removed. The remaining underlying insulation, vapor barrier and other roof assembly components are not disturbed.

While the coverboard is installed to protect insulation, it is not typically considered to be part of the roof insulation. This is significant because many jurisdictions require energy code compliance only if the insulation layer is exposed. Consequently, Jones Payne provides clients with two viable treatment options that can improve a roof’s overall thermal performance, while maximizing budgets.

  • Thermal Value Improvement – One layer of ½” compressed polyisocyanurate coverboard is installed and mechanically fastened through the insulation layer to the roof deck. Next, another layer of the polyisocyanurate coverboard is adhered to the mechanically fastened coverboard, and the roof membrane is applied to the adhered coverboard.  This approach increases the R-value of a roof by an average of R-5, and protects the underside of the roof membrane from wear caused by the fastening plates of the mechanical fasteners.
  • Thermal Value Code Compliance (Combination of Existing & Additional Roof Insulation) Older polyisocyanurate insulations have a higher thermal performance value than replacement insulation due to more stringent requirements now in place for manufacturers of new insulation. Therefore, re-using existing insulation preserves the R-value. Adding new insulation over the “split coverboard”, in combination with the existing insulation, typically brings a new roof assembly up to current, applicable codes.

BUDGET & ECO-FRIENDLY

The Jones Payne “re-use” approach provides innovative results and cost efficiencies that yield measurable value. While our method is ideal for metal or wood roof decks, since the uplift requirements can be achieved through mechanical fasteners, our team also treats other deck surfaces.  We recently completed a hybrid roof over a concrete deck utilizing RMA (Reinforced Mechanically Attached) wood curbs, which were used to support a “RhinoBond” roof fastening system.  This technique saved our client $200,000 over a typical full-tear-off roof assembly system.

Utilizing a sustainable design philosophy also reduces negative impacts on the environment. According to the U.S. Environmental Protection Agency, materials and roofing waste accounts for over 40 million tons, or 5 percent of all solid waste generated annually. Re-use of roofing materials, like insulation, offers a unique opportunity to significantly reduce landfill waste. And from our experience, it is also the best way to make the most use of available funding.