Modified Bitumen Roofing
The Complete guide
our Guide to Modified Bitumen Roofing
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.
Modified Bitumen Roofing Details
What is Modified Bitumen Roofing?
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.
APP vs SBS Modified Bitumen Roofing
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.
Benefits of a Modified Bitumen Roofing System
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.
Modified Bitumen FAQs
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.