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Commercial Roofing

3 PVC Roofing Attachment Options

By Karen L Edwards

January 22, 2019

PVC attachment

A typical PVC roofing system will consist of insulation board and membrane over the structural deck. As with other single-ply roofing systems, there are multiple ways to fasten the PVC roofing membrane.

Each option carries pros and cons. Factoring in the needs of the building owner, the ease of the contractor performing the installation, and a given area's possible weather conditions, here are three popular attachment methods.

1. Mechanically Attached Installation

mechanically fastened pvc

Contractors may choose to install the PVC using a mechanically attached method, which relies on specially designed metal plates and fasteners to attach the insulation to the deck and the membrane over the insulation to the deck.

Mechanically attached PVC roofing systems can be installed quickly and cost effectively. Mechanically attached systems tend to have lower wind uplift resistance compared to adhered or induction welded systems, however, this performance can be improved by using narrower PVC sheets and supplemental fasteners. Building codes and manufacturer specifications may provide guidance on how many fasteners are needed per square foot—a higher number may be necessary in high-wind areas.

2. RhinoBond® Installation

RhinoBond

The RhinoBond® Attachment System is an induction welded option that uses the same plate to fasten both the insulation to the structural deck and the membrane to the insulation.

Using this method, insulation boards are attached to the deck using the RhinoBond® machine, which installs a screw and a plate. After the PVC membrane is rolled out over the insulation boards, the seams are welded. The RhinoBond® machine then uses an induction welding method to weld the membrane to the plate below, creating strong attachment without penetrating the membrane itself.

3. Adhered Installation

pvc fully adhered installation

Some PVC roofing installations rely on adhesives to attach the membrane to the insulation board. However, these adhesives may not eliminate the need for fasteners in the system. Many adhered installations still rely on fasteners to attach the insulation board to the structural deck.

In an adhered membrane application, the PVC membrane is adhered to the insulation boards. For instance, a 2-part low rise foam adhesive can be used to adhere fleece-back PVC membranes for roof-recovers. The fleece-back PVC membrane can be applied directly over an existing asphaltic system with 2-part low rise foam.

Additionally, manufacturers like GAF are developing new solutions to help contractors efficiently adhere PVC membranes, like the EverGuard® PVC Quick-Lay Adhesive and the EverGuard® PVC Quick Spray Adhesive. EverGuard® PVC Quick‑Lay Adhesive is a one-sided, wet lay-in, water-based adhesive useful for bonding smooth EverGuard® PVC membranes to various substrates. EverGuard® PVC Quick Spray Adhesive is a sprayable, solvent-based contact adhesive useful for bonding smooth EverGuard® PVC and PVC KEE membranes to various substrates. Both EverGuard® PVC Quick-Lay Adhesive and the EverGuard® PVC Quick Spray Adhesive provide faster membrane installation than traditional solvent-based bucket and roller bonding adhesives.

The best attachment method for any PVC installation will depend on the building's location and function as well as any special weather conditions. If you are unsure about the right attachment method for your project, contact your GAF territory manager to review your project and help you determine the best solution.

About the Author

Karen L. Edwards is a freelance writer for the construction industry and has a passion for roofing, having worked in the industry for 20 years.

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The initial and supplemental roof insulation ultimately saves a net of 705 metric tons of carbon over the life of the building.If you want to see more examples like the one above, check out PIMA's study, conducted by the consulting firm ICF. The research group looked at several DOE building prototypes across a range of climate zones, calculating how much carbon, energy, and money can be saved when roof insulation is upgraded from an existing baseline to current code compliance. Their results can be found here. Justin Koscher of PIMA also highlighted these savings, conveniently sorted by climate zone and building type, here.Support for Carbon Investment DecisionsSo how can you make sure you address both operational and embodied carbon when making "carbon investment" decisions? 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If so, using it may be a good strategy.Next, determine if the alternative product or system can provide operational carbon savings, even if it has high embodied energy (upper-right yellow quadrant). If the alternative has positive operational carbon impacts over a long period, don't sacrifice operational carbon savings for the sake of avoiding an initial embodied product carbon investment when justified for strategic reasons.Last, if a product has high operational carbon savings and relatively low embodied carbon (lower-right green quadrant), include more of this product in your designs. The polyiso roof insulation in our example above fits into this category. You can utilize these carbon savings to offset the carbon use in other areas of the design, like aesthetic finishes, where the decision to use the product may be discretionary but desired.When designing buildings, we need to consider the whole picture, looking at building products' embodied carbon as a potential investment yielding improved operational and performance outcomes. Our design choices and product selection can have a significant impact on total carbon targets for the buildings we envision, build, and operate.Click these links to learn more about GAF's and Siplast's insulation solutions. Please also visit our design professional and architect resources page for guide specifications, details, innovative green building materials, continuing education, and expert guidance.We presented the findings in this blog in a presentation called "Carbon and Energy Impacts of Roof Insulation: The Whole[-Life] Story" given at the BEST6 Conference on March 19, 2024 in Austin, Texas.References:Architecture 2030. (2019). New Buildings: Embodied Carbon. https://web.archive.org/web/20190801031738/https://architecture2030.org/new-buildings-embodied/ Carbon Leadership Forum. (2023, April 2). 1 - Embodied Carbon 101. https://carbonleadershipforum.org/embodied-carbon-101/

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