Pros and Cons of Single-Ply Membrane Commercial Roofing
With today’s economy, property owners and managers face the daunting task of keeping their facility running safe and in decent shape. One of the most critical systems in a commercial facility is the roofing system. So, why jump into an investment without knowing the advantages and disadvantages of single-ply membrane roofing?
At West Roofing Systems, we have over 38 years of commercial roofing experience; we work with customers every day to decide what kind of roof is best for their facility.
While the choice is ultimately up to the building owner, we want to point out a few pros and cons to Single-Ply Membrane Roofing Systems.
Single-Ply Membranes are sheets of rubber and other synthetics that can be ballasted or chemically adhered to insulation to create a layer of protection for your commercial facility.
There are two main types of single-ply membrane commercial roofing: Thermoplastic Polyolefin (TPO) and Ethylene Propylene Diene Terpolymer (EPDM). They differ in their chemical makeup, how they are installed and their energy efficiencies.
Pros of Single-Ply Membrane Roofing
Proven Track Record
EPDM roofing has been used for commercial flat roofing for over 60 years. This amount of time on the market has allowed various laboratory and field studies to be performed and tracked. That’s why single-ply membrane roofing has a proven track record for being a high-performance roofing option.
TPO, while having more market share than EPDM, has not been on the market as long as EPDM. This means that TPO single-ply membrane roofing is still under testing and evolving into a more reliable roofing membrane.
Options for Insulation Materials
Since single-ply membrane roofing does not include the insulation factor, as a customer you have more options to choose from to insulate your facility’s roof. There are a few types of insulation options the facility manager/owner can to choose from:
- Polyisocyanurate (Polyiso) – The most used insulation type for roofing applications, Polyiso is more expensive but pay off with a higher R-value rating.
- Expanded Polystyrene (EPS) – With the highest R-value per dollar, EPS is used for roof, wall and floor insulation. EPS can be used with for ground contact and does not retain water over time.
- Extruded Polystyrene (XPS) – Usually defined by the blue, green or pink color, XPS falls in-between Polyiso and EPS in the range of price and performance. XPS is semipermeable with a perm rating of 1.
Choice of Reflective or Retentive Properties
TPO is fast growing in popularity across the commercial roofing market. Also, known as “White Roofs,” TPO is generally manufactured white and highly reflective. TPO is also available in tan, gray, green, blue and red.
On the other side of the spectrum, EPDM is often described as “Black Roofs,” due to the natural dark color of the membrane. This high-performance rubber compound provides excellent weatherability and heat retention beneficial for facilities located in climates with lower “cooling days”.
Unlike the complexities involved with processing spray polyurethane foam roofing, installing single-ply membrane roofing is relatively simple.
After the existing substrate is prepared, either by cleaning or removing the existing roof, the insulation layers are installed and covered by a cover board.
There are three ways to attach the membrane to the cover board: ballasted, with an adhesive or mechanically fastened.
The significant difference between TPO and EPDM comes when it is time to adhere the membrane seams together. TPO uses a hot-air gun to melt down the membrane at the seams and fuse them together. EPDM is joined together with a seam tape.
Lightweight and Flexible
Even though there are multiple layers, and you can choose the thickness of the membrane installed on your roof, overall single-ply membrane roofing is lightweight compared to other commercial flat roof systems. This relieves stress that is put on your building’s structure. (Excluding ballasted systems)
The flexibility of the single-ply membranes allows the contractor to accommodate unique roof designs. This flexibility also allows the roofing systems to stay intact with expanding and contracting buildings.
Cons of Single-Ply Membrane Roofing
Membrane is Easily Punctured
While we explained in the paragraph above that single-ply membrane roofing is lightweight and flexible, that also leads us to our first con, the thin layers are easily punctured.
Single-ply membrane roofing does not have a hard-top layer to protect the synthetic rubber from dropped tools, gravel or loose screws from being pushed into the rubber membrane. This kind of damage could create holes in the rubber and insulation and be vulnerable to leaks.
Most commercial roofing systems have accessories attached such as A/C units, skylights, air vents, plumbing vents and more. These penetrations on the roof can be in the way of rolling out a straight section of membrane.
When the contractor approaches these penetrations with single-ply membrane roofing, they need to cut smaller membrane pieces to size and essentially building up the roof around the vents/units which takes up more time and is not as reliable in terms of being waterproof.
Seams are Vulnerable to Leaks
We covered in the installation explanation how the rubber membrane is rolled out, overlapped and fastened with either heat, mechanical fasteners, adhesives or tapes. Although these seams are sealed, they are still areas that are more vulnerable to leaks than other roofing systems.
UV rays that shine directly on the roof can degrade the adhesives quickly over time. This is what can make those seams vulnerable to leaks. If there is a puncture, tear or other damage to the roof, the UV rays coming into the adhesive layer can cause more damage with the adhesives deteriorating.
Single-Ply Roofing Systems take up over half of the roofing systems for commercial, industrial, and manufacturing facilities that are looking for a sustainable, economically efficient option.
At West Roofing Systems, our goal is to get you a long-lasting roof that will protect your facility. That includes working with our award-winning team to choose the best roofing systems to meet your needs.
Contact West Roofing Systems today to talk to our expert staff about your future Single-Ply Membrane Roofing System.
Author: Jack Moore
Jack Moore is President and CEO of West Roofing Systems, Inc. With 21 years of SPF Roofing experience, West Roofing Systems has received numerous accolades for his leadership in the commercial roofing industry, including 18 industry excellence awards from the Spray Polyurethane Foam Alliance. He is an active member of the National Roofing Contractor’s Association and the Spray Polyurethane Foam Alliance.