Although simple and utilitarian, the most important aim of a roofing system is to maintain the watertight integrity of a building and keep its contents dry. Today’s variety of flat or low slope commercial roofing choices (roof pitches that range from 1/4:12 to 3:12) is no more straightforward and has grown considerably in the last 50 decades.
The objective of the guide is to help building owners, contractors and architects determine which commercial roof alternatives are ideal for each unique project. That’s a terrific question! Flat roofs are nothing new, nor are some of the established materials which cover those often-expansive roofs such as those located on factories, warehouses, big and little box stores, apartment buildings, big public structures, and schools/universities. A set roof’s design is both efficient and economical. Let’s explore the following topics as they relate to the Primary low slope roof systems:
- Product features, benefits and differences
- Attachment options
- Overall maintenance and warranties
Following a recent overview of this Manual of Low-Slope Roof Systems* (hereafter known as the Manual), this guide will be referenced through this report.
The National Roofing Contractors Association (NRCA) offers a strong website and resources geared for builders about everything roof related. Their easy-to-navigate website provides a comprehensive overview of materials, applications, classes and other tools for contractors and building professionals. On the NRCA micro-site Everybody Needs a Roofing, building professionals and owners can find out more about the importance of appropriate roofing materials and applications, locate contractors and even ask experts questions regarding all components of roofing.
Even the 2015-2016 NRCA Market Survey shows that roof system forms across the U.S. still reflect the most current trends in non-scale commercial roofing applications. The poll results reveal TPO since the low-slope market pioneer, devoting a 40 percent share of this new construction market and 30% of their reroofing market. EPDM follows next, capturing 22 percent of market share for new construction and 26% of their reroofing market. In the third position is Mod Bit at 12.4 percent of the new construction marketplace and 14 percent of their reroofing market. Market share for all these and other system options follow by percent in the chart below:
ROOFING SYSTEM
The Less-Than-10-Percent Group
Liquid Applied and Spray Foam Roofing Systems
Liquid applied membrane systems require rigorous preparation of this substrate, which has to be sterile and invisibly together with patched cracks.
While liquid applied coatings are highly elastic, self-flashing and easily applied to contoured surfaces, they have reduced permeability and need uniform thickness. The NRCA offers an internet course Design Principles for Roof Performance: Liquid-applied Roof Membranes for a comprehensive look at liquid-applied roof membrane options.
Metal Roofing Systems
As one of the world’s oldest roofing systems, metal roofing began with substances like the bronze tiles Rome’s early Pantheon. Lead roofing later joined bronze as a popular option for cathedrals and castles across Europe during medieval times. Steel, aluminum, stainless steel, and tin also are employed in commercial metal roofing applications. Benefits to metal roofing including longevity, durability and heat resistance. Furthermore, metal roofs can resist high winds and so are largely impact resistant. However, the investment for a metal roofing alternative probably will be much higher upfront compared to other flat roofing alternatives.
The Metal Construction Association (MCA) provides resources for people interested in knowing more regarding the use of metal as a very low slope roofing alternative. The MCA touts metal as a preferred low pitch roof covering for commercial, institutional and industrial buildings due to its capacity to protect against the elements, to allow water to drain from your roof surface and also keep building contents and occupants dry. To assist building specialists, the MCA conducts numerous technical research and research projects in partnership with member and industry partners designed. All these free tools contain bulletins, white papers, manuals, and reports.
New Metal Roof System Applications:
Low incline structural metal roof is commonly known as a standing seam roof and is made up of interlocking panels that run vertically across the roofing surface. These panels usually arrive with a painted mill complete or even a clear acrylic finish. Some metal roof used on low pitch software requires machine seaming during setup to ensure a watertight seal. A seaming device is only rolled along the panels to crimp the panel seams together.
A standing seam design guarantees adequate draining from snow and rain, effectively removing ponding, leaks and relevant issues. In the end, very low slope metal roofs are not prone to the degradation experienced by a few organic materials, allowing these roofs to resist the components. This might create a longer life span and low annual operating expenses.
Metal Roof Restoration Applications:
In retrofit jobs, a sub-framing method is attached to the current flat roof to offer a minimum 1/4:12 roof pitch. Alternatives for the removal of a metal roofing coating include acrylic coatings made from polymers that cure to form a durable, constant elastomeric membrane across the surface of the metal roof and can be added to metal roof systems to deal with your building’s particular needs around waterproofing, rust and UV protection. These oil coatings are designed to adhere to virtually any metal surface to produce a smooth watertight seal over the entire roof. Acrylic coatings are both water-based, non-flammable and emit no toxic fumes. These systems can defy the most common types of roof risks, such as ultraviolet light, temperature extremes, mold, and regular foot traffic and building motion.
Vegetative Roof Systems
While not on the list concerning market share, yet another roofing system should be said — the vegetative or “green” roof. These roofs have living plants which are ordinarily installed in tray methods on the top of the horizontal roof surface. Vegetative roofs may effectively provide an advantageous method for stormwater management. Keep in mind roofing membrane for a base to the machine is extremely important to maintaining the roof’s integrity and water tightness. To learn more on vegetative roofing systems, make sure you visit Green Roofs for Healthy Cities.
The Basics on Asphalt Roofing Systems
Together with a selection of other famous manufacturers, Industries offers a full line of asphalt based commercial roofing systems. A long-dependable alternative for low slope roofing, asphalt drops into three basic classes: Built Up Roof, Modified Bitumen and Hybrid Systems (a combo of Mod Bit and BUR). By SBS into APP along with BUR, asphalt employed membrane methods include base sheets, including cap sheets along with self-adhered membranes.
Built Up Roofing (BUR) Systems
Popular in North America for more than 100 years, Built Up Roof (BUR) Systems are composed of alternating layers of bitumen (asphalt) and materials known as roofing felts. The felts are reinforced with glass-fiber mats or organic mats (metal sheets) and when joined with all the bitumen type a permanent roofing membrane. The amount of “plies” onto a roof implies the number of layers, i.e. “four plies” finds a four-layer flat roof membrane system.
BUR systems are somewhat redundant, meaning if a single coating breaks, multiple staying layers provide immediate protection. These programs also offer excellent tolerance for building tension and immunity to thermal shock, high puncture resistance and exceptional tissue strength and toughness for proven long-term durability.
BUR systems can include SBS, ceramic or natural felts and provide many options to suit a variety of building requirements. The trick to this system is the repetitive layers. BUR also is famous for superior fire resistance from external flames. Reflective surfacing choices are also available to offer greatest membrane protection, exceptional puncture resistance and high resistance to foot traffic and mechanical care.
Modified Bitumen (Mod Bit) Systems
Mod Bit methods incorporate factory-fabricated levels of asphalt that are “altered,” using a rubber or plastic component for greater efficacy and combined with a psychologist for added strength and stability. Bitumen (or asphalt) is really a tacky, black, and viscous fluid or semi-solid kind of oil. It is found in natural deposits or might be a refined product and is used for the two road surfacing and roofing. Bitumen displays a high-quality caliber when softened with heat.
APP and SBS refer to the kind of polymers which are added to the asphalt. A variety of reinforcements are used with all the asphalt, including fiber, fiber, and polyester mats and scrims. The scrim is a strengthening fabric made from continuous filament yarn in an open mesh construction.
Mod little membranes are typically set up as two- or – three-ply (multiply) system. The sort of modifier used can establish the process of sheet setup: mopped down using hot asphalt or asphalt welded to melt off the asphalt so it flows on the substrate. Seams are secured with precisely the exact same technique. The membrane system may be stored in place on the roof by fully adhering the bottom sheet, automatically attaching the bottom sheet or employing ballast.
High performance modified bitumen waterproofing and roofing systems are quickly installed, easy to keep and cost-efficient. Mod little membranes are normally hot mopped like conventional BUR but also may be applied as a flashlight down merchandise. The Manual summarizes some important points to consider with every installation process, such as:
- Hot Cleanup is generally safer and quicker than torching.
- If warm asphalt is necessary for additional roofing operations to stick a base sheet, then it is likely more economical to warm mop the cap sheet also.
- Heating welding (also known as “flashlight down”) can evaporate surface moisture in the bonding region.
- Heating welding preheats and softens substance, offering benefits in cold weather.
Mod Bit Systems Options:
HEAT WELDED ROOFING SYSTEMS
Heat Welded Roofing Systems include both base sheets and cap sheets in either a granule or smooth surface. A number of specially designed heating welded systems are available, including Armourplast™ APP Heat Welded Cap Sheets, the Prev ENt™ line of fire rated cap sheets and Torch flex™ SBS Membranes in the base and cap sheets. Designed to decrease labor and installation time, the Torch flex Roofing System can provide large office buildings and industrial warehouses that have several years of protection.
Fully Adhered Roofing Systems contain those that are stuck with hot mopped asphalt allowing joining of the membrane to the substrate. Roofs are considered completely adhered if applied right to roofing decks or insulation. From PrevENt™ Fire Ranked Premium Heavy Duty Cap Sheets to Modiflex™ Cap and Modiflex Base Sheets, those durable fully adhered products will add life and strength to your roofing system.
Proven products such as Fast-N-Stick™ Base Sheets ensure a safe and trusted roofing system that contractors can depend on.
Fire Rated Roofing Systems are designed to handle extreme temperatures and to mitigate fire. The PrevENt™ line of top SBS cap sheets provides enhanced performance with graphite technologies for the highest fire resistance rating (Class A) available in a set roof membrane. Graphite is put on the upper face of the reinforcement mat during a production of the cap sheet and functions as a fire retardant by expanding quickly when exposed to high temperatures. In the case of fire, then graphite cuts off the supply of oxygen into the flame.
Reflective along with Eco Roofing Systems offer reflective properties designed to give protection against the harmful effects of the sun and ultraviolet rays. From ArmourCool™ to the brand new fire-resistant Carrara™ ArmourCool HD, all these membrane systems install like a standard cap, are reinforced and built to last, offering a substantial contribution towards improving building energy efficiency and cost savings into the building operator.
Single Ply Membrane Systems
The single ply roofing systems marketplace has grown exponentially in the previous 40 years. Considered a reliable business roofing program, single plies offer you a protracted service life and require relatively low maintenance. Oftentimes, commercial single-ply roof systems have been backed by a manufacturer’s guarantee.
The Manual provides a comprehensive history of the background on modern roof systems as well as a discussion of those substances and research which are part of the history. The authors state that a combination of economic and technological variables resulted in what they refer to as the”only compound revolution,” such as:
- Frustration with traditional bituminous roofing supplied a marketplace of building architects and owners keen to try something new
- long-term tendencies toward prefabrication favored the less labor-intensive field installation of new, lighter stuff versus the significant field labor required of the conventional systems
Single ply roofing techniques provide durability, flexibility and long-term durability. The inherent advantages of these pre-fabricated sheets would be the consistency in quality of the goods which are manufactured, the flexibility of their attachment techniques and their wider applicability.
There are two major categories of chemical membranes: thermosets and thermoplastics.
Thermoset membranes are made of rubber polymers. The most commonly used polymer is EPDM or Ethylene Propylene Diene Monomer. EPDM is a lasting plastic roofing option and accessible in both black and white. Thermoset membranes are successful to be used as roofing materials due to their proven ability to withstand the potentially harmful effects of sunlight and many common substances usually found on roofs.
All these factory-made sheets are implemented on the job website using one of the standard installation techniques for sheet membrane systems (completely stuck, mechanically attached or ballasted). This procedure is repetitively supplied the material is not heated above the point at which decomposition occurs. The membranes may be welded together with warmth or solvents, also when compacted, create a bond strength which equals or surpasses the strength of their base material.
Specifying the ideal choice for a single ply system depends on many things, including price. On the other hand, the choice shouldn’t be based on cost alone. Other critical considerations are building elevation, wind exposure, anticipated roof visitors and aesthetics. In any scenario, consider the track record of the maker and the standing of the roofing companies.
Single Ply Attachment Approaches
The project and situation will help ascertain the ideal attachment process. If the roof deck may withstand the burden, then a ballasted (loose rock) roof could possibly be the best choice. But when the slope of the roof is greater than 2:12, then this system may not be appropriate. Other limitations to using a ballasted system may include roof height, proximity to shorelines and other large wind zones and availability of ballast.
A deck which takes fasteners readily, like steel or wood, makes a great substrate for a mechanically fastened membrane. These programs are designed to offer the necessary resistance to known wind forces and are not subject to pitch constraints.
Another attachment technique is a fully adhered system, in which the membrane is connected to the substrate utilizing a predetermined adhesive. Based on the veins, the glue might be solvent-based, water-based or asphalt. The final surface of a stuck roof will be smooth. Colored membranes could be used which may provide an appealing aesthetic into the building’s appearance.
How Do I Create My Final Decision on a Professional Roof System?
If you have come this far in the summary, you’ve read about the multitude of system choices for industrial roofs. While the choices are many, you might have narrowed it down to what suits the requirements of your job and budget. As mentioned previously, the NRCA’s Everyone wants a Roof micro-site provides a terrific overview for facility staff and building owners to help them understand the characteristics and differences between low-slope roof membranes.
Added Resources:
The association includes many North American producers of asphalt shingles and asphalt low slope roof membrane systems.
- The Canadian Roofing Contractors Association (CRCA) contains businesses actively participated in Canada in the roofing and related sheet metal building firm, along with companies engaged in manufacturing or supplying materials and services utilized in any branch of the roofing and sheet metal industry.
- Cool Roof Rating Council — The Cool Roof Rating Council (CRRC) is an independent firm which developed a method for providing building code bodies, energy service providers and architects/specifiers with precise information about roof surfaces to help enhance the energy efficiency of buildings.
- EPDM Roofing Association — The EPDM Roofing Association, known as ERA, is a trade association representing the manufacturers of EPDM roofing products and their providers.
- Polyisocyanurate Manufacturers Association (PIMA) PIMA is a trade association representing the producers and suppliers of polyiso insulation throughout North America.
- RedVector.com Red Vector offers online education for professionals in the engineering, architectural, interior design, construction, land surveying, building inspection, and landscape architecture industries.
- RICOWI — The Roofing Industry Committee on Weather Issues, Inc. (RICOWI) was created in 1990 as a nonprofit organization to identify and address important technical issues linked to the reason for roofing wind damage.
For those interested in learning more about residential flat roofs, please visit our official website: https://skywalkerroofingnc.com/
Christy Wilson
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