Learning about single ply
With our piece today, we are going to answer common questions and tell you all about TPO roofing, otherwise known as Thermoplastic Polyolefin. This single-ply roofing membrane is popular on commercial roofing systems and s made with a single layer of synthetics with a reinforcing scrim.
This single-ply roofing is ideal material for commercial and flat roofs. Ethylene Propylene Diene Terpolymer, also known as EPDM, is another single ply roofing material. Both of these are sheets of rubber combined with other synthetics and are adhered to the insulation by ballasting or chemically, creating a layer of protection for the building.
The difference between the two is their chemical makeup, the installation process, and their energy efficiencies. There are valid single ply roofing pros and cons to consider when choosing single ply roofing for commercial structures. The pros of single ply roofing are:
Proven Track Record: EPDM has the longer track record because TPO hasn’t been around as long, but with more than 60 years in the industry, EPDM has proven to be a durable roofing material TPO single ply roofing has a bigger market base now which would indicate that it is a close second, maybe even tied with EPDM.
Insulation Material Options: Insulation isn’t a factor with single-ply roofing membranes, so this gives a commercial building owner more options in choosing the insulation material. Some of the options include:
- Polyisocyanurate – The more expensive choice but the most popular choice of single ply roofing insulation with a higher R-value rating.
- Expanded Polystyrene – A higher R-value for the dollar and can be used on the single ply roofing or in the walls and on the floor since it doesn’t retain water.
- Extruded Polystyrene – A mixture of the other two in regard to cost and performance.
Reflective or Retentive Properties: TPO is the “white roof” single ply roofing which highly reflective and comes in other colors of blue, gray, green, red, and tan. EPDM on the other hand is the “black roof” but is a high-performance rubber compound that provides excellent weather resistance that is beneficial for commercial structures where the weather is cooler.
Easy to Install: TPO is the easier single ply roofing to install than spray polyurethane foam roofing. Once the existing roof surface is cleaned or removed, TPO is either installed ballasted, using an adhesive or fastened mechanically and seams are adhered with a hot-air gun that melts the membrane seams, fusing them together.
Flexible and Lightweight: Even though TPO has multiple layers, there are thickness options, so it the fewer layers, the more flexible and lightweight. This eases the weight limit on the building’s structure.
The cons of single ply roofing are:
Easily Punctured: Because TPO single ply roofing is flexible and lightweight, this makes it susceptible to punctures. There isn’t a hard layer to protect this synthetic rubber membrane for screws, tools, or other items being dropped during contractor services. Because it punctures easily, it can be vulnerable to leaking.
Accessories: Commercial roofing typically has HVAC system, plumbing vents, skylights, and other penetrations on the roof. These penetrations can make TPO single ply roofing installation challenging because it can be rolled out straight without interruptions. This make the install job take longer, which can cost more in labor. It also creates more places for possible leaks where the TPO material is pieced together around the penetrations.
UV Rays: The sun’s UV rays can degrade the adhesive used to install TPO single ply roofing material. That degrading can weaken the seams and make the roof more vulnerable to leaking.
Which roof type would a single ply roof membrane be installed on?
With single ply roofing, the installation varies depending on the building and the situation. Ballasted roof would be the preferred installation method if the structure can handle the weight. However, if the roof slope is more than 1″ in 6″, then it wouldn’t be the best method.
A single ply roofing that is mechanically fastened is best on a steel or wood roof and for any type of slope. This is an excellent application for areas prone to hurricanes. A single ply roofing that is fully adhered is another option to consider if the membrane can be attached with an adhesive.
What is the best material to use for flat roofs?
Even though PVC roofing is the more expensive single ply roofing material, it is the most preferred choice for use on flat roofs. The benefits are plentiful, which offsets the cost. Those benefits include:
- Impact resistant
- Crack resistant
- Low maintenance
- Longer lifespan
- Energy efficient
How long does single ply roofing last?
When you hire experienced single ply roofing contractors that professionally install a single ply roofing, you can expect a lifespan of thirty years. This also requires the roofing be properly maintained and kept up as needed with repairs by the owner of the building.
How do you install a membrane roof?
The key to a membrane roofing installation is that it is done by experienced professionals. This will insure the durability and longevity of this single ply roofing. The first step is to install an insulation board such as EPS or ISO foam board with an R-Value of 4-R to 6-R per each inch. This step is important to get the full energy efficiency possible.
There are three methods to installing a PVC roofing membrane:
FULLY-ADHERED: The membrane and substrate are attached with a special adhesive. This is a fast and easy method and has one big disadvantage. Condensation forming under the membrane when ventilation is poor.
MECHANICALLY-ATTACHED: Attaching the membrane to the substrate with barbed plates and heavy duty screws will hold the membrane tight, even hurricane proof.
BALLASTED: This method is laying the membrane loosely over the substrate and hold it in place with a ballast of either manufactured concrete pavers or washed river rock.
How do you apply single ply roofing?
EPDM and TPO are applied in the same manner until the point of adhering it to the structure. Both are rolled out after the existing roofing has been cleaned or removed. Then the EPSM is secured using seam tape and an adhesive in some situation. TPO is attached with an adhesive or mechanically fastened, then the seams are welded together with hot air.
Up on The Roof Top
Which is better, Single Ply Roofing vs Built Up? Well, as we mentioned earlier, TPO is the new kid on the block. EPDM has been around 60 years and Built-Up roofing has been around 100 years. It will depend on the type of structure, the health of the structure, and the environment, as well as the budget as to which one is best.
EPDM and TPO are either ballasted or chemically adhered to insulation. Built-up systems are alternating layers of asphalt/tar with supporting fabrics directly to the roof. The single ply roofing is less expensive (approximately half as much). Your commercial roofing contractor can provide more details on these types of roofing and make recommendations. Call 469-858-2448 today to learn more.
