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What Is Modified Bitumen Roofing Material

The Advantages Of Tpo Roofing

GAF Tri-Ply Modified Bitumen Products Overview | GAF Roofing

TPO roofing hasnt been around for nearly as long as modified bitumen, as it was introduced to the roofing industry in the 1990s. However, TPO has rapidly grown in popularity since its introduction. As with modified bitumen, TPO roofing is very straightforward to install, and it can also often be installed directly over an existing roofing system. It is highly water resistant thanks to its heat-welded seams, and it also stands up well against chemicals like oil and grease. Finally, TPO roofing is a fairly green material, as it is fully recyclable and readily available in lighter colors that reflect heat and keep buildings cool more efficiently.

Why Is Bitumen Used In Roofing

Bitumen has been utilised for its adhesive and waterproofing qualities for over 5,000 years, making it one of the oldest known engineering material still used today. It is particularly popular in the roofing industry, as it can create a watertight structure which is proven to stand the test of time.

Sbs Modified Bitumen Vs App Modified Bitumen

SBS modified bitumen roofing and APP modified bitumen are two very similar roofing materials. Both roofing materials are bitumen membrane roofing sheets made out of asphalt. However, the difference lies in the way the materials are modified.

Manufacturers make APP modified bitumen by adding plastic. In order to make SBS modified bitumen, they use rubber. Both roofing materials possess greater flexibility than traditional BUR roofing systems, but SBS is the more flexible choice of the two. Regardless of which roofing option you go with, make sure you purchase your modified bitumen roofing material from a trustworthy manufacturer to ensure your sheets are consistent in quality and thickness.

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What Is Modified Bitumen Roof

Modified bitumen roof is one of the many materials for roofing using widely in the USA and Canada. This material stands much better under certain climate conditions. But what is it, and why should we know about this material?

In this article, we will discuss this specific roofing material and other things related to the material you need to know.

What Is Modified Bitumen’s Framework


The Modified Bitumen membrane has five layers of construction to give it the same durability and resistance as a BUR multi-ply roof. This system consists of asphalt bitumen, modified polymers, and polyester or fiberglass reinforcements permeated together to create a waterproof barrier that can resist harsh weather, fire, debris, and foot traffic.

The layers of a single-ply Modified Bitumen roofing system start with the structural deck covered with a vapor barrier layer that adds waterproofing.

A layer of insulation goes next to provide R-value , topped with a layer of adhesive. The top layer is the modified bitumen membrane with a pressure-sensitive SecurTape strip for additional hold.

Additional layers stacked on top of each other made of asphalt and Modified Bitumen membranes can make the roof thicker and more durable.

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Application Methods For Modified Bitumen Roof

There are different types of Modified Bitumen roofing systems to install. Below we are going to read about the two different types of installation of Modified Bitumen roofing. Two types of Bitumen roofing installation are: Torch-Down installation method and a peel and stick installation method.

Tools used in the installation of Modified Bitumen Roofing

Modified Bitumen Roofing Installation And Warranty

The installation of your modified bitumen roofing system, when properly installed, is a fast, non-intrusive process.

A modified bitumen roofing system can be installed using the torch method, asphalts, or cold adhesives. A standard SBS modified bitumen roof system is a two-ply system applied in rolls overlapping the edge of the previous roll. The following can influence the end result of the roofing systems installation:

  • Proper roof slope for efficient draining
  • Correct installation and fastening of insulation to deter bulging and/or sagging
  • Correct application of adhesives to the substrate
  • Proper overlapping of MB material
  • Drip edge seamlessly connected around the perimeter of the roof

In addition to high-quality installation, a warranty is advantageous and very valuable when the installation or components of your roof fail. There are two types of warranties you should consider when installing or replacing this or any roofing system:

Contractors Warranty This warranty covers the workmanship and installation of your roofing system by the contractor. The contractor can guarantee their work for a set time period , or for the lifetime of the roofing system. A contractors warranty should contain the following:

  • A complete list of covered items
  • What actions or events may void the warranty
  • When/If the warranty expires

The above installation and warranty information underscore the necessity to thoroughly vet contractors before starting roofing installation/replacement.

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The Advantages Of Modified Bitumen

Modified bitumen began to see widespread usage for a few key reasons. To begin with, its straightforward to installmuch more so than the built-up roofing systems it was designed to improve on. The ease of installation and ready availability of its fundamental materials also makes it quite affordable, as it typically costs less than TPO. Finally, modified bitumen is fairly waterproof, tear-resistant, and flexible, enabling it to survive shifts in temperature.

What Is A Sbs Roofing System

Modified Bitumen Roofing Systems

May 28, 2021

When it comes to commercial and industrial roofing, the industry is continually changing. Roofing materials are more diverse than ever, still, bituminous roofing membranes remain a popular choice. There is one among the market that has proven to be especially popular: SBS roofing systems.

In this article, we have outlined some general information about a roofing system commonly used in commercial and industrial roofing. Using the information provided, we hope to help you find out how an SBS roof can benefit your property. Heres what you need to know about SBS roofing systems.

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The Benefits Of Modified Bitumen Roofing

Although commercial roofing systems are made from a range of materials, one stands above the rest as the most popular and reliablemodified bitumen roofing. Its a versatile material ideal for flat and low-slope roofs. Its an affordable choice too.

Lifetime Roofing Utah, your local commercial roofing contractor, discusses its other features and benefits.

Minimum Slope For A Membrane Roof

When we say flat roof, we dont mean perfectly flat, which is undesirable since water still needs to be shed to roof drains. Technically, we are talking about low-slope roofs that have a slope less than or equal to 3:12. You can read our article about calculating slope for information on the various roof slope notations.

The minimum slope for a flat roof is 1/4 per foot or 1/4:12, but some owners or insurance companies require a minimum slope of 1/2 per foot. The idea is to provide positive drainage toward roof drains so there is no ponding water 48 hours after a rain storm. The slope can be accomplished by sloping the structural deck, using tapered insulation, or a combination of the two methods.

Always check with the roofing manufacturer to confirm the designed slope meets their warranty requirements.

It is also advisable to check with the owners insurance company to confirm their coverage requirements some insurance companies have more stringent criteria for wind speeds and roof uplift. FM Global provides roofing design guidelines in their Roof Deck Securement and Above-Deck Roof Components Data Sheet, which is often referenced in architectural specifications.

There are more economical solutions available for steep sloped roofs. Read our article about steep sloped roofing systems.

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The Framework For Modified Bitumen Roofing Systems Is A Five

  • Insulation Used to provide R value, or thermal resistance, for temperature stability of the roof system
  • Modified Base Sheets or Plies
  • Modified Bitumen Membranes Factory fabricated sheet membrane composed of co-polymer reinforced with polyester or fiberglass
  • Adhesive Waterproofing material with a bonding agent applied either hot or cold
  • Surfacing Provides UV protection and weathering resistance

What Is A Five


The framework for a Modified Bitumen Roof is a five-layer combination of roofing components that make up the roof membrane.

  • Insulationâ Used to provide âRâ value, or thermal resistance, for temperature stability of the roof system.

  • Modified Base Sheets or Plies

  • Modified Bitumen Membranesâ Factory fabricated sheet membrane composed of co-polymer reinforced with polyester or fiberglass

  • Adhesiveâ Waterproofing material with a bonding agent applied either hot or cold

  • Surfacingâ Provides UV protection and weathering resistance

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Weight And Thickness Of Modified Bitumen Roofs

Individual sheets of mod bit are typically between 120 mils and 180 mils thick.

A typical sheet of modified bitumen roofing weighs about 1.1 lbs. per square foot.

The vast majority of installed mod bit roof membranes have two plies, a base sheet and a cap sheet. So the average modified bitumen roof membrane is about 300 mils thick and weighs around 2.2 pounds per square foot.

Additionally, layers of insulation and cover board below the roof membrane itself may lead to a total depth of the roof system of up to several inches. The actual depth of the roof system will depend on the type of insulation used and the total roof system R-value requirements of the local energy code.

Mod Bit Can Be More Expensive

While re-covering an existing modified roof with a single-ply mod-bit cap sheet is very cost-effective, installing more than one ply drives up cost quickly. When installing a two- and three-ply system, one is effectively roofing the roof 2 or 3 times. Speed of installation is an area where thermoplastics really shine. Multi-ply mod-bit systems are significantly more expensive on large roofs.

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Tpo Vs Modified Bitumen Roofing

by John Bert | Jun 3, 2021 | Roofing

Choosing roofing materials can be tough. For residential buildings, shingles are so common that they are easy to justify, but for many commercial buildings, they dont suffice. That means that commercial building owners have to explore many more roofing options, and they need to truly understand the differences in their choices in order to do what is best for the building.

Thats a tall order, but it becomes easier when the knowledge is broken into digestible chunks. With that in mind, we want to take you through two of the most popular roofing materials typically used in commercial construction. Those materials are TPO and modified bitumen. Well show you the strengths and weaknesses of each so that youll know enough to decide which is right for your roof.

Modified Bitumen Membrane Roofing Types:

Installing Self-Adhering Modified Bitumen System Garland Roofing

modified bituminous membrane roofing is categorized into two types-APP and SBS

1. APP Roofing System Membranes:

Atactic polypropylene is commonly known as plastic asphalt. APP membrane contains a plasticized polymer that shows elasticity property when going through high temperatures.

It protects the house from UV rays and also gives the structure of the roof a cool look. It is preferred by people who want to protect their house from extreme conditions.

2. SBS Roofing System Membrane:

Styrene-butadiene-styrene is referred to as elastic of rubberized asphalt membrane, it contains asphalt with polymerized rubber which gives it the flexibility and elasticity property. If your roof expands and contracts in extreme climate conditions, it is one of the best types to choose. SBS roofing installation also protects the house from high winds.

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Modified Bitumen Roofing : Features And Benefits


Commercial properties use different types of materials for their roofs, one of which is modified bitumen. It was first used in Europe in the early 1960s and in the US in the mid-1970s. Today, it remains one of the top choices for flat and low-sloped roofing.

What is Modified Bitumen?

Modified bitumen roofing in Columbus, Ohio is composed of polymer modified bitumen reinforced with one or more layers of fabric. This could be polyester, glass fiber, or a combination of both. This type of roofing can be installed using conventional methods such as hot or cold application or self-adhered.

You can choose from two types of modified bitumen membranes:

  • Atactic Polypropylene This type of modified bitumen roofing is a thermoplastic polymer that is either heat-welded or torch-applied. It is known to give asphalt a plastic-like quality.
  • Styrene Butadiene Styrene This type of modified bitumen roof is installed using cold adhesive or hot moppings of asphalt. It may also come with adhesive backing. Modified bitumen SBS conveys a rubber-like appearance.

Modified bitumen is manufactured in factories and sold in sheets. It is specially made to have equal thickness and physical properties throughout the entire sheet. A finished roofing membrane can have one or several bitumen sheets, but it can also have a combination of built-up roofing felts and one or more modified bitumen sheets.

Why Choose Bitumen Roofing?

Rolled Roofing Vs Modified Bitumen Which Is Best

Roofing is arguably the most critical aspect of any house. Its clear to see why. A roof protects your home from the elements of mother nature. From freezing snow to pouring rain to blaring sun and more, a roof is meant to protect you, your loved ones, and your home. Choosing the best roof for you is a decision that you need to take seriously.

Nowadays, there are many different types of roofing available. However, some types of roofing are better than others. Two of the main types of roofing available that you can have today are rolled roofing and modified bitumen. These two types of roofing are very different from each other but can both be excellent choices for roofing for your home. So which one is better? Here are a few things to know about rolled roofing and modified bitumen so that you can find out which one is the best choice for you.

Modified Bitumen roofing is better than asphalt roll roofing materials in both longevity and durability. The most significant advantage of modified bitumen is that it is durable and lasts 20 to 30 years. However, the disadvantage is that its harder to install and repair, making labor costs higher. As a result, some roofing contractors dont work with modified bitumen materials.

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Modified Bitumen Roofing Product Properties

Modified Bitumen
– 2-ply self-adhered base using Firestone MB Base SA + either an APP or SPP cap sheet
Two-Ply SBS or APP, Cold-Adhesive SBS or APP base sheet cold-adhesive bonded to cover board SBS or APP cap sheet cold-adhesive bonded to base sheet

Typical application: installed over cover board mechanically glued atop solid insulation that has been mechanically attached to the roof deck.

Two-Ply SBS glass fiber reinforced base+cap sheet SBS glass fiber reinforced cap sheet torch applied over SBS base sheet. Typical application: installed over two layers of foam board insulation both mechanically bonded to the roof deck & together

Notes to the table above

1. APP = atactic polypropylene products.

2. SBS = styrene-butadiene-styrene products. SBS polymers are blended with asphalt to obtain properties of flexibility & resistance to thermal movement at low temperatures.

3. BUR = built-up roofing systems

Both APP & SBS modified bitumen roofing from Firestone include a fiberglass / polyester reinforcing non-woven mat. SBS flashing is used on traditional built-up roof roofing systems

SBS cap sheets & flashing are used on hybrid BUR roofing systems SBS base sheets, cap sheets & flashings are used in 2-ply modified bitumen roofing systems. Firestone’s literature describes the product’s reinforcing fiber mat as including both non-woven polyester fibers and continuous glass fiber materials integrated into a single reinforcing fabric.

Modified Bitumen Roofing Explained

Modified Bitumen Roofing

Modified Bitumen roofing is an asphalt-based roofing system closely related to the Built-Up Roofing design. This roofing material is suitable for buildings with low-scope or flat roofing. MB roofing originated in Europe in the mid-1960s and was adopted widely as a commercial roofing material across the US.

Engineered MB roofing material is popular because it performs optimally in harsh conditions, including cold weather. Mod-bit roofing consolidates into typically three to five layers of roofing components, making it one of the most trusted and durable flat roofing systems.

The elements making up the modified bitumen roofing system include:

  • Insulation. This feature provides thermal resistance or the R value for temperature stability. It also provides a solid surface for the new roof system to be installed over.
  • Modified Base Sheets. Base sheets are critical foundations for flat roofs cap sheets offer redundancy when other layers develop a support problem. This is the first ply installed.
  • Modified Bitumen Mid Ply Sheets. These are factory-fabricated sheet membranes composed of co-polymers reinforced with fiberglass or polyester. These are typically installed on plys 2-4
  • Modified Cap Sheet. The top sheet that is typically installed with granules. This sheet provides weathering resistance or UV protection. This is the top ply installed, and what most people see what they look at a modified roof.

Benefits of Modified Bitumen Roofing

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How Modified Bitumen Is Made

Mod bit is produced by blending raw asphalt with polymeric additives which increase the durability, strength, and flexibility of the asphalt. The final product will contain anywhere from 3% to 15% of the polymer additive, depending on the manufacturer and the specific type of product.

Mod bit maintains a more uniform strength and flexibility over a wider range of temperatures compared to the unmodified asphalt used in built-up roofs.

Modified bitumen roofing is manufactured in sheets, with layers of modified asphalt applied to each side of a reinforcement fabric, much the same way as asphalt shingles are made. The reinforcement fabric is made from either fiberglass or polyester, or a combination of the two.

The finished mod bit sheets are typically 39 inches wide and sold in rolls. The rolls are typically between 25 feet and 33 feet long.


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