Polymer Modified Self-Adhered Membranes have revolutionized the roofing industry in recent decades, but what exactly are they, and how do they work?
In this post, we’ll explain common misconceptions associated with SBS and APP-modified membranes specifically designed as a self-adhesive membrane. In addition, we will explain exactly what a self-adhered membrane is and how its techniques differ from other types of polymer-modified membranes. We’ll also take a look at the history of self-adhered membranes and delve into their benefits as a multi-layer membrane roofing system.
The technology of polymer-modified self-adhered membranes has been used for decades as leak barrier membranes in both commercial and residential construction. The popularity of polymer-modified membranes continues to grow today. This evolution into the low-slope roofing market has driven the development of self-adhered modified bitumen roofing membranes, which feature an adhesive bottom layer that bonds the membrane to a wide range of common roofing substrates.
The use of polymer-modified membranes is commonly two or more layers, thereby these systems are given the name Modified Built-Up Roofing (MBUR). There are two main configurations of modified bitumen membranes commonly used in the industry: APP membranes and SBS membranes. Within these two types, extra components are added to the modified bitumen formulations to enhance certain characteristics such as flexibility.
APP membranes contain a plasticized polymer called atactic polypropylene within their formulation. This makes them more flexible but in a plastic-like characteristic as compared to the SBS membranes, which contain a type of synthetic rubber known as styrene-butadiene-styrene, these having more rubber-like characteristics.
Polyglass has been an industry-leading innovator of self-adhered roofing membranes and underlayments for decades. These products utilize advanced technologies such as ADESO® Self-Adhered Technology and innovations such as FASTLap and SEALLap Ultra. We’ll explore these in more detail so keep reading.
The History of Self-Adhered Membranes
The roofing industry has undergone several evolutions of change since the turn of the 19th Century. Initially, roofs were installed using simple asphalts or derivatives with coal-tar pitch, which gave off extremely unpleasant odors and what are now known as noxious fumes during installation due to the heating process.
During the 1970s and 1980s, modified bitumen began to gain traction versus more traditional asphalt built-up roof materials. Modified bitumen was considered by some, as easier to use, and could be applied with fewer layers for most roof applications. However, some common application techniques such as open-flame torching and solvent adhesives resulted in odors and posed safety risks.
Self-adhered membranes emerged in the 1990s thanks to pioneers at Polyglass, who unveiled a patented innovation called ADESO Self-Adhered Technology. This development set the standard for self-adhered modified bitumen membranes, which are now increasingly common across the roofing industry. Some statistics indicate this as the driving factor to the growth of polymer-modified membranes.
Polyglass has continued to develop ADESO technology for decades and now offers a wide range of self-adhered membranes as well as underlayments bolstered by further innovations such as FASTLap® and SEALLap® Ultra which offer installers added benefits during the installation process.
Self-Adhered Membrane Application Methods
Self-adhered membranes differ from other types of BUR or MBUR roofing membranes due to the methods used during installation. Rolls of self-adhered membrane sheets are laid across the roof in overlapping layers and they bond in place using a factory-applied adhesive layer on the bottom of the sheet. No dangerous tools or open-flame torches are required.
A commonly used application method for installing MBUR roofing systems is a heat-welded application. This is often used for both APP and SBS membrane systems. The membrane roll is heated using a torch with an open flame that puts out over 400.000 BTUs of heat. This intense and focused flame converts the solid bottom compound into a semi-fluid bottom surface bonding it to the roof substrate. The membrane fuses during its semi-fluid state and upon cooling completes its bonds to the surface.
The torch application method involves risks. Though controlled, this open-flame tool can be dangerous to both occupants and workers as it requires a pressurized propane fuel source to create 400,000 BTUs of heat, which can present a fire risk.
Another common application technique used to install an MBUR roofing system is the cold-applied adhesive method. This technique doesn’t require the use of an open flame for the field of the roof but some products do require torching of the overlaps. The adhesive used to bond the membrane is most commonly a solvent-based liquid product that is applied to the substrate, and then the membrane is placed into the adhesive. As the liquid flashes off VOCs, it softens the backside of the membrane creating a bond to the substrate.
This method may remove the risk of open flame in the field of the roof, however noxious odors are present. When open flame is required at overlapping joints, this subjects the flammable adhesive to the open flame used to seal the laps which can increase the hazard level. Another consideration with cold adhesives is that they do have climactic conditions such as higher heat conditions and low colder temperatures.
Benefits of Self-Adhered Membranes
Compared to other application methods, self-adhered roofing membranes have several benefits that can make them an ideal choice for nearly any roofing project.
1. Cost Effective
Often, the initial labor costs can be lower because self-adhered membranes are much quicker to stage and store as there are fewer accessories needed for its installation, and no kettles, pails of adhesive, or propane bottles to handle. Secondly, self-adhesive membranes properly installed are a simplified application process as compared to other systems. Self-adhered membranes can also cost less as they require fewer labor steps to install, and are simplistic to service and maintain as compared to other systems types.
Insurance coverages can also be a factor, be it the installing contractor or building owner. Many roofing contractors can simply not obtain general liability insurance coverage to allow them to use open-flame torches. Likewise, insurance provided for a building owner may restrict the risk and types of roofing allowed on the building. The design and use of a self-adhered membrane system mitigate such risks.
2. Durability
MBUR systems are historically known for their redundancy and durability when put to the test by climate extremes. Self-adhered membranes are no exception to this historical performance, especially when compared to other single-ply systems that do not provide multi-layer protection. A properly installed self-adhered membrane offers exceptional seam integrity, creating a stronger seam when tested on many other system types. Self-adhered membranes have already shown over 20 years of field performance and are comparable to any commercially available roof system type.
3. Ease of Installation
Self-adhered roofing membrane systems offer clear and concise installation methods and require knowledge that any reasonable roofing installer can master. This helps save time as a contractor and decreases labor costs, no more need to pick the most highly trained personnel. Without the need for open-flame torches, this too reduces risk and can allow a wider range of workers to become masters at installing self-adhesive membrane systems.
4. Environmentally Friendly
Because of the absence of torches, solvent adhesives, or hot asphalt, self-adhered membranes are a much more environmentally friendly overall system. The installation of self-adhered membranes doesn’t give off any harmful and noxious fumes during the installation process. This is also a favorable situation for building occupants as they are not exposed to secondary odors and hazards.
Spotlight on ADESO Self-Adhered Technology
For the creator and leader of self-adhered roofing membranes, look no further than Polyglass’ industry-leading ADESO Technology, celebrating its 20th anniversary of successful in-service performance. This technology is available across the majority of Polyglass’ roofing membrane types for low-sloped use, as well as the entirety of their Polystick roof underlayment line for steep-slope applications.
ADESO SA-modified bitumen membranes utilize a dual-compound construction that features APP or SBS membranes on the upper weathering layer alongside a powerful adhesive bottom layer. Ground-breaking innovations such as FASTLap and SEALLap create robust seams while making the membrane system easy to install.
ADESO Technology is used within a broad range of materials and can offer any installer advantages and successful performance. From the Elastobase SA base sheets and Elastoflex SA P cap sheets to underlayments like Polystick® XFR Polyglass offers a self-adhesive option for all your roofing needs. As Polyglass expands into the entire building envelope, an even wider range of self-adhesive membranes are there for the protection of the entire building not limited to just the roof.
For more information on Polyglass’s ADESO product range, click here to find the perfect self-adhered underlayment or membrane for your next client project.