Modified Bitumen Roofing
The Complete Guide
The modified bitumen roof has emerged as a go-to system for commercial, industrial, and institutional buildings over the last 50 years.
Its flexible endurance and ability to provide improved energy efficiency while withstanding the elements make it a money-saving darling.
The fact that an adequately maintained modified bitumen roof enjoys a life expectancy of 25 years or longer makes it an excellent investment.
If you recently sustained damage or need to replace an aging roof, these are reasons to consider a modified bitumen roof installation.
In this modified bitumen roofing guide ››
You're going to learn everything you need to know about modified bitumen roofing, so you can make an informed decision about your next roofing project.
The modified bitumen was developed during the 1960s as a cost-effective alternative to the complex built-up roofing (BUR) system.
Used primarily on a low-slope or flat roof, membrane layers are comprised of asphalt bitumen infused with polymers and fiberglass reinforcements that adhere to a commercial flat roof.
The modified bitumen membrane roof provides cost-effective and weather-resistant benefits few can rival.
There are two modified bitumen roof installation schools of thought that revolve around peel-and-stick materials and the torch down method.
A peel-and-stick modified bitumen roofing installation is largely used by building maintenance workers in an effort to save money.
These products tend to fail at a greater rate than a professionally installed torch down roofing system.
In a torch down roof, the roll roofing layers are laid down and an experienced modified bitumen roof installation specialist employs an open flame to heat the membrane.
The hand-held propane torch raises the temperature of the materials until it adheres directly to the underlay and the seams are melded together.
The torch down roofing system delivers a consistent and comprehensively sealed defense against water penetrations, and it also deflects UV rays.
It’s important to discuss the specific modified bitumen roof installation needed to best protect a commercial building.
Two of the more cost-effective options involve 2-ply SBS modified bitumen membranes and 3-ply hybrid roofing systems.
The 2-ply SBS modified bitumen roll roofing products are pre-fabricated and available in a wide range of thicknesses. It is typically constructed as a torch down roof.
By contrast, 3-ply hybrids may involve the hot mopping modified bitumen membrane roof material similar to the BUR process.
A commercial building with a low-slope or flat roof may be a good candidate for a torch down roof installation using either APP modified bitumen or SBS modified bitumen.
When expertly installed, either modified bitumen membrane roof can deliver many years of protection against the elements and help keep energy costs low.
But the APP and SBS modified bitumen membranes are made from different base materials that involve the following.
- APP Modified Bitumen: APP modified bitumen membranes are generally a type of torch down roof. These membranes are manufactured with plastomeric and generally contain a type of plastic called atactic polypropylene. This makes APP modified bitumen roll roofing materials more rigid once installed.
- SBS Modified Bitumen: Comprised of a type of synthetic rubber called styrene-butadiene-styrene, SBS membranes maintain greater elasticity and flexibility. SBS modified bitumen can be installed as a torch down roof using heat, cold adhesives, or as a self-adhering membrane.
The heat employed in the torch down roofing system tends to be modestly different when installing APP modified bitumen or SBS modified bitumen roll roofing materials.
The APP materials require higher temperatures to melt, making the consistency more fluid to some degree. By contrast, SBS roll roofing products become sticky at lower temperatures.
APP Modified Bitumen Roofing
An APP modified bitumen roofing installation delivers a plastic-like appearance and quality that increases UV ray protection and water mitigation roof health.
The torch down roofing system utilizes heat at temperatures of 300 degrees or hotter to melt materials and mop across the surface.
The APP modified bitumen roofing system remains a preferred choice for smaller areas and regions that mostly experience temperate weather.
An APP torch down roofing system ranks among the more cost-effective and enjoys a life expectancy of more than 20 years, when adequately maintained.
SBS Modified Bitumen Roofing
Commercial, industrial, and institutional buildings with low-slope roofs are generally good choices for an SBS modified bitumen roofing installation.
Considered reliable and affordable, the modified bitumen membrane roof system ranks among the most trusted in terms of water resistance and its ability to withstand damage from extreme weather.
Its flexible membrane allows it to negotiate sudden temperature swings. Although widely installed as a torch down roofing system, other processes can be employed when a slope dictates.
It’s important for commercial building owners and property managers to understand that modified bitumen roofing involves a great deal more than a single layer of roll roofing material.
A deftly constructed modified bitumen roof installation includes multiple layers of materials designed to maximize energy efficiency and protect the structure and its contents from rain, hail, and high-wind storms. These include the following.
- Insulation Layer: A low-slope or flat roof requires a thick layer of high-quality insulation to prevent heating and cooling losses. Modified bitumen roofing technicians attach a layer of insulation through a strategic system of screws and plates. In other cases, glue or hot mopping may prove the best way to secure the insulation to a flat roof.
- Vapor Barrier: A vapor barrier is usually installed directly above the insulation. The purpose of a vapor barrier in a modified bitumen roof is to prevent moisture buildups due to condensation. Moisture can weaken structural supports or lead to hazardous mold growths.
- Overlay Board Installation: A torch down roofing system calls for a protective cover board to rest above the vapor barrier and insulation. Installing overlay requires the skill of an experienced modified bitumen roof installation professional. A poorly installed overlay can result in water ponding on the surface of a modified bitumen roof.
- Base Sheet Installation: Considered the first layer of the modified bitumen membrane roof material, the base sheet may be heated with a torch or hot mopped.
- Cap Sheet Installation: The outer modified bitumen membrane roof layer is generally smooth and melted together through a heat process. An initial roll roofing material clings to the base sheet below and a commercial building may require multiple layers. Once pressed together, they form a secure roofing system able to protect the structural integrity of a building for decades.
- Parapet and Other Flashing: Piping, HVAC systems, and any parapet that rises above the low-slope or flat roof requires flashing and sealants. In many instances, metal flashing is commonly used to prevent water penetrations around the edges of a parapet. Rounded pipes generally call for industrial-grade sealants or a combination of both.
If you need a specific type of modified bitumen product, just ask. Other modified bitumen manufacturers include: Owens Corning, GAF, TAMKO, IKO, Certainteed, Firestone, Malarkey, Johns Manville, Atlas, Mule-Hide, Versico, Soprema, Polyglass & others.
Modified Bitumen Roof Warranties
GUARANTEED BY THE MANUFACTURER
As a Certified Roofing Contractor for multiple manufacturers, RestoreMasters offers warranties up to 30 years on modified bitumen roofing systems.
A modified bitumen roof offers substantial benefits over other roofing systems in key areas.
Here are a few benefits of a modified bitumen roofing system:
Fast and Cost-Effective Installation
Although a modified bitumen roofing system delivers layers of insulation and weather protection, the installation process remains relatively straightforward for experienced professionals.
An efficient modified bitumen roofing contractor saves property owners time and money on their investment.
Low-Maintenance and Easy to Repair
A modified bitumen roof requires little maintenance, and rarely do they sustain damage.
A low-slope or flat roof sometimes requires repair to flashing or sealants as they age.
If high winds or hailstone strikes cause damage, technicians can easily secure the affected areas.
Extremely Durable and Flexible
A torch down roofing system employs highly durable and flexible materials that resist high winds, intense temperature swings, and hailstorms.
And commercial building owners can select multiple modified bitumen roof layers to meet their needs.
Maximize Energy Efficiency
A modified bitumen roofing system can be designed to reflect solar and thermal energy.
Sometimes called a “cool roof,” the improved efficiency helps property owners lower HVAC energy consumption. A dark flat roof can also absorb sunlight, making it warmer to some degree.
Regardless of the strategy, a modified bitumen roof installation provides ample insulation and coverage to eliminate energy loss.
Long Life Span
A modified bitumen roof installation lasts 25 years or longer, depending on maintenance and upkeep.
The factors determining whether a flat roof installation maximizes life expectancy involve quality installation, membrane thickness, and extreme weather events.
A durable modified bitumen roof resists tears and impacts better than others in its class.
How long does a modified bitumen roof last?
The life expectancy of a modified bitumen roof depends on wide-reaching factors. These include professional installation, ongoing maintenance, and routine inspections.
A poorly treated flat roof may time out as early as 10 years. A well-maintained modified bitumen membrane roof can last for 25 years or longer.
What is the difference between modified bitumen and BUR roofing?
Built-up roof (BUR) systems were adopted in the U.S. back in the 1800s. This design employs heavy layers of tar or asphalt to insulate a flat roof.
By contrast, a modified bitumen roof utilizes relatively lightweight insulation, vapor barriers, and membranes that are fused together.
While both may be viable flat roof options, a modified bitumen roof installation places less weight on load-bearing infrastructure and requires less labor.
Can you repair a modified bitumen roof?
The short answer is: Yes. However, lack of maintenance and care leads to roof leaks that cause water damage.
Once rafters and support beams have been compromised, modified bitumen roof replacement may be necessary.
That’s why it’s crucial to schedule annual inspections and make minor repairs as needed.
Can you walk on a modified bitumen flat roof?
The short answer is: Yes. However, foot traffic and equipment impacts are leading causes of flat roof damage.
When walking on a modified bitumen roof, it’s essential to tread lightly and act cautiously when using heavy tools or equipment.
How often does a modified bitumen flat roof need to be inspected?
Scheduling an annual inspection with a modified bitumen roofing contractor identifies early warning signs that minor repairs are needed.
This process typically saves tens of thousands of dollars in unnecessary building restoration costs later. It’s also prudent to schedule a flat roof inspection following a high-wind storm or hailstone strike.
Modified bitumen roofing requires an experienced commercial roofing contractor. Modified bitumen roofing is a specialty field of roof installation and complex roof systems require careful craftsmanship and adherence to strict manufacturer standards.
If your roof has suffered hail or wind damage, you will want a contractor that can work with you every step of the way. One that is able to perform emergency roof repairs as needed and total installation.
Look for a modified bitumen roofing contractor with the following qualifications:
- Is licensed, bonded, and insured in your state
- Trained & certified by the manufacturer to offer the best quality and warranty options
- Experience installing your type of flat roof on multiple projects
- Experience managing staged roofing projects that may require parallel tear-off and installation
- Experience working with insurance companies on damage claims
An experienced roofing contractor can help you avoid leaks and major problems and provide a roofing systems that lasts for decades.
In 2021, RestoreMasters was ranked #31 of the Top 100 Roofing Contractors in the nation.
In addition to modified bitumen roofing installation, RestoreMasters offers: all common types of roofing systems, shrink wrap roofing, roof tarping, loose lay membrane roofing, emergency roofing & repair, water mitigation, water damage restoration, mold remediation, catastrophic damage inspections, property damage documentation, testing & damage reports, fencing & perimeter security, disaster recovery services, permanent roof replacement, interior restoration services. and general contractor services.
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