What is a Self-Adhesive Roofing Membrane
Self-adhesive roofing membranes cover a wide spectrum of applications and are very versatile. Self-adhesive roofing membranes are probably the most versatile of commonly used roofing products. Self-adhesive roofing membranes come in membrane types that can be used for low-sloped and steep-sloped roofs, asphaltic or non-asphaltic membrane/system designs. The adhesives used for self-adhesive membranes, though most commonly asphaltic, can be non-asphaltic such as Butyl. Polyglass manufacturers offer a broad range of self-adhesive membrane products for nearly any roof or wall condition to waterproof or weatherproof any construction condition.
As the name suggests, self-adhesive membranes offer a simplified application process—simply remove the release film and apply the membrane to the surface with the adhesive side down. This method eliminates the need for open-flame torches, smoky asphalt kettles, or odor-containing adhesives, providing not only a quicker installation but also a safer application. Self-adhesive membranes bond well to nearly all clean and properly prepared substrate types. The bond of Polyglass SA membranes forms upon installation and continues to strengthen over time as the membrane remains in service.
What are the typical uses for Self-Adhesive Roofing Membranes
Steep-Slope Roof Applications
When discussing options for steep-slope roof coverings, the usual cast of characters enters into the discussion;
- Asphaltic Shingles
- Concrete Roof Tile
- Clay Roof Tile
- Metal Panels & Stamped Metal Pieces (mimicking tile or shakes)
- Wood Shakes & Shingles
- Composites
Even the best and most expensive roof coverings are designed to shed water and require an underlayment. While building codes may only require a lightweight, organic, loose-laid felt fastened to the deck, this provides little to no weather protection if the roof covering is lost due to wind or another storm event. The roof covering and underlayment work together to shed surface water, but if the roof covering is damaged or lost, the underlayment is often compromised as well, leaving the structure vulnerable to water intrusion.
However, self-adhesive membranes bond directly to the deck, serving as a secondary water barrier for any roof covering system. By providing a fully bonded layer of protection, these membranes are impermeable, meaning that once properly lapped, neither liquid water nor water vapor can penetrate the self-adhesive underlayment. With the exception of a few specific roof coverings, such as seamed and rolled metal panels, most steep-slope roofing products rely on overlapping layers to function as water-shedding systems. This is why all steep-slope roofing systems have specific minimum slope requirements—without the proper slope, they will not perform effectively or meet Building Code standards.
Areas around chimneys, vents, skylights, and roof edges are also vulnerable to leaks. So, for these conditions, it is especially important to use an underlayment that will tie the details together and perform in a watertight manner.
Another important factor is that underlayments need to be fastened to the deck using thousands of nails, thereby putting holes through the underlayment membrane. Self-adhered membrane bonds to the substrate and only requires backnailing at the overlaps so all fasteners are hidden and covered by a second layer. Even in those applications that require fasteners to be exposed and penetrate the roof underlayment, a self-adhesive underlayment seals around the penetrating fasteners and is part of the test standard (ASTM D 1970) to ensure fasteners do not leak.
Low-Roof Applications
When discussing options for self-adhesive low-slope roof coverings, these are less commonly known by the average consumer, so a more in-depth discussion is needed, but the more commonly used are;
- Asphaltic Modified Bitumen Membrane (APP and SBS)
- Thermoplastic Polyolefin (TPO)
- PVC
- EPDM (vulcanized rubber)
The common thought when discussing low-sloped roof types is often an “out of sight, out of mind” discussion. Rarely does the average person look at a low-slope building design and wonder, “Gee, I wonder what type of roof is on that building.”
Historically, low-sloped roofs have been considered “commercial” roofing products, and to some extent, this is not untrue. Whether installed on a house or a commercial building, the basic membrane materials remain the same. Many have believed that installation requires smelly asphalt kettles, high-BTU open-flame torches, or solvent-based adhesives.
Challenges and Solutions; Self-Adhesive is the Answer
With all roofing products come unique challenges, some of which are easy to overcome and some are far less easily dealt with.
Open Flame Torches or Heat-Welding
Many asphaltic membranes such as APP-modified bitumen are designed for heavy-duty services and more challenging application situations. In these types of situations, an APP-modified Bitumen system can be a very common choice and it is well-suitable. However, there are those wood deck scenarios in which the increased fire risk must be a top priority. For those conditions, self-adhesive APP-modified bitumen membranes can be the solution. Offering the redundancy of a multi-ply roof and the superior exposure weathering of an APP-modified asphalt, it may be the ideal option.
Hot Asphalt and Solvent Odor and Equipment complications
When considering a cold-adhesive system or an adhesive-bonded membrane, there are unique challenges that must be addressed first. On larger projects, adhesives for most roof types are typically applied using high-pressure equipment, which can introduce noise and the risk of equipment failure. Once the adhesive is dispensed on the roof, it is important to evaluate how much solvent or adhesive odor is tolerable for workers, building occupants, and the surrounding public. Additionally, rooftop mechanical systems that draw in outside air as part of their operation can inadvertently introduce solvent odors into the building.
Numerous systems can utilize hot asphalt which requires large bulky kettles that impede on a building’s space and cause an exposure risk to the surrounding public. Like solvent odors, those from the hot asphalt will also be able to be brought into the building as a noxious smell for occupants.
In self-adhesive systems, the “adhesive” is already integrated into the self-adhered membranes, so you do not need to prepare and apply it separately. There is no mixing, applying, and waiting for the adhesive to reach the right tackiness or cure level before proceeding. It is ready to go as soon as the backing is peeled off. The factory-applied adhesive is evenly and optimally distributed, which also eliminates any inconsistencies in thickness and coverage that come with manually applied adhesives. The use of fewer materials allows for work to be done faster and cleaner with less site debris.
Less Project Equipment
With the ease of primary and secondary materials, the entire process requires less loading and storage equipment, allowing for a less cluttered project site. Loading materials to the rooftop is a simplified one-step process. Rolls can simply be loaded roof-top by crane, conveyor, or other equipment capable of transporting rolls from the ground of the delivery truck to the roof.
The simplified process requires less loading time for equipment like nail guns, compressors, torches, propane tanks, etc. used in other membrane applications. This not only speeds up the job but also makes it safer and less cluttered, which is always a benefit on complex or steep roofs.
Seams and Laps are Simplified
Seams and laps of self-adhesive membranes are simplified. Ensure membranes are laid straight and the proper overlapping width and simply apply pressure and in some cases flameless heat
Self-adhered membranes are designed with precise edge areas that have enhanced adhesive properties. When one roll overlaps another, these areas align to automatically create a tight seal. The factory-applied, consistent adhesion helps to make sure there are no weak spots along the seams; this is always a concern with manually applied adhesives where inconsistency might result in leaks.
As soon as the protective backing is peeled off and the membrane is pressed down, the adhesive activates and forms a waterproof bond. There is no curing or drying time necessary, and the seal starts protecting from moisture immediately.
Reduced Waste Management
Traditional roof systems inevitably wind up with significant amounts of cutting and trimming, resulting in membrane pieces that cannot serve another purpose. Traditional systems also utilize many secondary materials, such as adhesives in pails, hot-asphalt packing, etc. Most self-adhered membranes come in rolls with minimal packaging compared to other materials which reduces the amount of waste. Simply put, there is less waste to dispose of at the job site.
Using self-adhesive membranes also eliminates the risk of adhesive spills or drips that can occur with manually applied options. Cleanup not only wastes time but you are also forced to use industrial-grade absorbents or cleaning solvents. Since self-adhered membranes are easy to cut and fit to the roof’s shape, there is less scrap and offcuts left over as well. Most cut-offs can be utilized for patches or other flashing conditions.
Importance of Choosing a High-Performing Roof
This discussion has ventured into a variety of roof choices and types for both steep-slope and low-slope roof designs. In doing so, we are reminded of the complications that are a part of many traditional roof choices. In nearly any condition, self-adhesive roof membranes offer an alternative to other options. In addition, self-adhesive systems can offer a simplified application, with the potential for reduced labor and waste, thereby making it a sustainable choice.
The use of a self-adhesive roofing system does not take away the virtues we require from our roofing options, it adds a level of ease and simplicity. Self-adhesive systems offer high-performance products and when considering modified bitumen self-adhesive products, they can offer value that is not matched by more traditional systems.
Building codes set minimum standards for systems and processes. Manufacturers are increasingly driving the importance of using as a minimum, Code compliant materials and systems. According to the Building Code in the State of Florida, in hurricane-prone areas, roofs must have a secondary water barrier thereby using a self-adhesive membrane over the entire deck or at minimum to all joints in the wood decking. The Building Code in the State of California specifies that for roofs in areas with high wildfire risk, an underlayment to aid in bringing the roof covering to a Class A rating.
Many jurisdictions within higher climate zones within the US have to use an ice barrier that consists of at least two layers of underlayment cemented together or a self-adhering membrane sheet must be used in places where the January average temperature is 25°F (-4°C) or lower.
ADESO self-adhered technology is a patented method developed by Polyglass that checks all these boxes. It combines two distinct layers of compounds in a single membrane: an aggressive self-adhesive on the bottom layer to form a tight bond to prevent water from getting underneath and to ensure the membrane stays fixed in place over time; and a cutting-edge modified bitumen compound on the top layer designed to withstand UV rays from the sun, resist tearing, and cope with thermal expansion and contraction caused by temperature changes.
Polyglass’ ADESO membranes are engineered to give you better durability and reliability compared to traditional membranes where a single compound is rarely able to perform both functions as powerfully. To learn more about the ADESCO product range and get your hands on the most advanced self-adhered underlayment for your next project, contact us here.