Modified Bitumen Roofing system is the common low-slope roofing system. It is not like the asphalt roll roofing, TPO, or EPDM. Modified Bitumen doesn’t consist of hot asphalt with plastic and rubber additives. Between sheets of polyester or fiberglass, they are layered.
In the mid-1960s in Europe modified bitumen first appeared in commercial roofing. The conventional roofing system was built-up roofing. It is made of a layer of asphalt with a top layer of gravel.
The BUR is very useful but it has some downside too like it is heavy, it is expensive to install, it doesn’t work well for extreme temperatures and it is difficult to repair.
It was successful in resolving the problems with BUR, it is easy to install and it is working properly even in extreme temperatures like cold weather. By 1975, modified bitumen is being used in the United States. Now it is one of the most reliable roofing systems.
Today in this post you learn about what is modified bitumen roof?, how to install modified bitumen roofing?
What Is Modified Bitumen Roof?
Modified Bitumen Roofing system is the common low-slope roofing system. It is not like the asphalt roll roofing, TPO, or EPDM. Modified Bitumen doesn’t consist of hot asphalt with plastic and rubber additives. Between sheets of polyester or fiberglass, they are layered.
This type of roofing is typically used in Seattle because it gives resistance to tearing. The fiberglass and polyester reinforcement layers help the material to become tear-resistant.
There is everything in the article you want to know about Modified Bitumen Roofing. You come to know about what is Modified Bitumen roofing, its history, how to install it, its type, its advantages, and disadvantages. By knowing all of this, you can know what kind of roofing you want to do in your house.
It also gives the waterproof characteristic to the roofing. It also handles foot trafficking well. So it has good advantages over another roofing system which you will read below in the article.
You can take a look at the advantages and disadvantages of the system and compare it to others. Though there are disadvantages in this system it can be solved by maintenance and precautions. And the advantages weigh down the disadvantages. It has many advantages which are preferred by many house owners. Hope so you get some good out of this article.
The framework of the Modified Bitumen Roofing system is a combination of five-layer roofing components.
The five layers are:Insulation Modified Base Sheets or Piles Modified between membranes Adhesive Surfacing
1. Insulation: This layer is used to give R-value or thermal insulation resistance for the temperature stability of the roofing system.
2. Modified Base Sheets or Piles: this layer gives the system the flat surface it has.
3. Modified between membranes: It is a sheet membrane that contains co-polymer reinforced with polyester or fiberglass. This membrane is fabricated in factories.
4. Adhesive:Â This layer is added for waterproofing. It can be applied on the surface of the roof either cold or hot.
5. Surfacing: This layer provides protection from UV rays and is used as weather resistance.
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What Are the Benefits of Modified Bitumen Roofing?
There are various benefits of modified Bitumen roofing that are as follows:
- Energy Efficient: Most of the modified roofing systems provide resistance from UV rays. And because of which the houses are able to maintain the inner temperature well. And It does not affect the HVAC system much. So it saves on the energy bills.
- Tear-resistance: Modified bitumen gives fantastic durability and strength to the roof. It provides resistance from the tearing of the debris, weathering, and consistent of foot traffic.
- Waterproof: It also protects the house from moisture. If it is installed properly it gives waterproofing protection to the roof. And because of its multiple layers, it is more efficient in waterproofing.
- Flexible: It contracts and expands easily with changing weather conditions. It is flexible in it working method and doesn’t lose its efficiency.
- Easy to Install, Repair and Maintain: It is very easy to install, so it helps the staff to install it. It is easy to repair if there are any leaks or cracks. It can be maintained well.
Modified Bitumen Membrane Roofing Types:
modified bituminous membrane roofing is categorized into two types-APP and SBS
1. APP Roofing System Membranes:
Atactic polypropylene (APP) 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 (SBS) 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.
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
- Measuring tape
- Hammer
- Chalkline
- Large propane torch
- Utility knife with a hook blade
- Spark igniter
Materials used in the installation of Modified Bitumen Roofing
- Roof insulation
- Heavy roofing felt
- Modified-bitumen roofing
- Drip-edge and other flashings
- Spray primer
- Cap nails
- Roofing nails
- Roofing cement
So here is a step-by-step guide to built up modified bitumen roof.
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How to Install Modified Bitumen Roofing?
The process of the installation of the Torch Down Bitumen Roofing are as follows:
- This process is dangerous for those who want to do it by themselves as it involves working with petroleum products and felting. Because of the work required to be done using fire, it must be done by professional roofing. So here is a step by step guide to install torch-down modified bitumen roofing:
- First, you have to check the roof properly and get rid of all the debris in the area for better results.
- Overtop your decking, insulation or old roof install heavy roofing. Secure the felt properly by using cap nails to the rows along the top and bottom and the sheets. And repeat that for the middle rows.
- Drip edge flashing should be installed in this step and then the primer should be applied so the roofing will adhere to it.
- In this step, you have to roll out the sheet of roofing leaving an overhang for a few inches on all the sides of the roof. Then again allowing a few inches of overhang on the roof, cut the roofing.
- Adjust roofing in a way it can overhang the flashing by a half-inch and check the roofing, it should be perfectly flat otherwise the installation won’t work properly. Then carefully roll back the roofing back up tightly halfway.
- For this step, you have to wear heavy gloves and long sleeves for protection from a propane torch.
- Turn on the propane torch and spread the tip of the flame along the crease between the roofing roll and the roofing felt. Gently roll the roofing forward with your foot when you see bubbles forming, for the process of installation.
- The next sheet should be aligned in a way so, that it can cover the edge of the sheet of modified bitumen roofing by a few inches. And after that repeat the process again.
- Press the seam between the two sheets using your foot and gloved hand. Then ensure that it is tightly sealed. A bit of melted bitumen should be oozed out along the joint.
- Repeat this process for the remaining portion of your flat foot.
How to Install a Peel-And-Stick Modified Bitumen Roofing?
It is built up modified bitumen roof is a type for do-it-yourself. As it does not involve working with fire and fumes, you can do it by yourself. So here are the steps to install peel-and-stick modified bitumen roofing.
First, five-step is exactly similar to the torch-down modified bitumen roofing installation which is written above. After following those steps, then you can start working on the steps which is written below.
First, you have to remove the adhesive film and carefully roll the roofing back into the original place. Before adhering the material to the flat roof, ensure that it is smooth out. Leaving an overlap of at least six inches, repeat this process for the entire area of the rooftop.
Roll over the entire area of your roof by using a weighted roller. Pay special attention to the overlap, otherwise, it will not be done properly.
Seal the edges of the Modified Bitumen Roofing with the help of roofing cement. Then roll all the sheets together to seal them together.
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Modified Bitumen Roof Problems
The problems of the Modified Bitumen roofing system are that it has low life expectancy than other roofing system. It can work well for 10-20 years approximately. Then you have to change the system or upgrade it.
It is one of the main reasons that people choose another roofing system as they want their roof to last for a long time.
It is not easy to install if to choose torch-down modified bitumen roofing. As it involves working with the fire and heat. In the installation process, a blow torch is used to extreme heat to install sheets on top of the roof. If you come in contact with harmful fumes it can be dangerous.
It has also a problem with the drainage system, as it is a flat roof it doesn’t have to the drainage system. The water gets collected on the surface of the roof and if the water is not removed quickly it can be absorbed by the roof. It can create mold and mildew in the roof.
It can be coated faster than other types of flat roofs. The modified bitumen roof system gives off a strong unpleasant odor after the installation process is complete.
How Long Does a Modified Bitumen Last?
Modified Bitumen Roof System can last for 10-20 years. Which is less time in comparison to another roofing system. The amount of time Modified  Bitumen roofing lasts depends on many things.
Like the materials used, if the system is installed properly or not, if it is checked frequently and if there is any issue repair should be done properly, and maintained well.
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Advantages of a Modified Bitumen Roofing
Here are some advantages that installation of Modified Bitumen Roof System provide:
- Seamless connections: There are three ways to install modified bitumen roofing- self-adhesive, cold adhesive, and heat. These are the reasons why the sheets are seamlessly connected properly. It has efficient adhesive nature which made the connection between the sheets of the roof durable.
- Tear resistance: It is made by a combination of fiberglass and polyester reinforcement. Which made the sheets tear-resistant and durable. It also handles foot traffic well. Because of this, it doesn’t have to be repaired quite frequently.
- Weather resistance: The modified bitumen roofing system is a composition of five-layer to withstand extreme conditions in all climates. It doesn’t allow much heat to pass through the roof to the house. It is also good for cold weather. And it also works efficiently in other environmental conditions.
- UV rays and heat resistance: This system is well known for its heat-reflective property. Because of the heat reflection, it protects the house from harmful UV rays, which is not only bad for the house but also for the people living in it. This reduces the house’s energy bill. So it is a money-saving scheme in the long term.
- Leak resistance: It is a flat roofing system that is leakproof. The materials used in this system help the area to be leak-proof for a long time. Its coherent nature made it easy to do that.
- Style options: The materials used in this system have several varieties, which help you to customize it according to your taste. The color of granules in the cap sheet can choose according to the color of the shingles used in the roofing of your house. The outside look it gives can be chosen by you because of the different types of materials used in this.
- Easy to install and repair: It is easy to install. It can be done by yourself. The peel and stick installation modified bitumen roofing method can easily be done by you. There are rolled sheets 3feet wide and up to36feet long, which can be rolled easily on the top of the base sheet of the roof. The repair can be done easily and quickly by using bitumen patches on the cracked surface.
- Environment friendly: The sheets used in this can be recycled. You can reuse the sheets with dumping outside. It not only saves you money but it helps in reducing the waste of the material which is good for environmentally. It reduces the carbon footprint.
Disadvantages of a Modified Bitumen Roof
Here are some disadvantages of the Modified Bitumen Roof system
- Lifespan: The average life expectancy of the Modified Bitumen Roofing is 10-20 years. It is quite a good time for the roof but if you compare it with other systems it is very low time. Other types of flat roof systems sustain for more years than this. So if you want your house to be protected for the long term there are better options for a roofing system than this.
- Water resistance: The absence of the drainage system on the flat roofing system makes it quite difficult for water to run down the roof. Water gets collected on the surface of the roof which spread the moisture in the house. Which can turn into mold or mildew at any time.
- Modified bitumen in comparison to other flat roof types like TP or PVC, wears down faster. It can damage the roof if it doesn’t get repaired immediately.
- Torch fumes: During the modified Bitumen roofing installation process blow torch are used to extreme heat, to install the sheets on the roof. Those fumes can be harmful if it comes in contact with people. It also gives some health issues. And it gives good effect to the environment.
- Foul odor: It gives a strong odor after the completion of the process of installing the Modified Bitumen System. The effect of the odor depends on the area covered in the installation. It is better to relocate temporarily during the process of installation of the roofing system is going on. It will help you to avoid the foul smell of the roofing system.
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Frequently Asked Questions (FAQ)
What Is Modified Bitumen Roof?
Modified bitumen (MB) roofing is a cousin of asphalt-based, built-up roofs (BUR). Modified Bitumen Roofing system is a combination of five-layer roofing. This layer includes Insulation, Modified Base Sheets or Piles, Modified between membranes, Adhesive, and Surfacing.
How Long Does a Mod Bit Roof Last?
Mod bit roofing system can last for 10-20 years. Which is less time in comparison to another roofing system. The amount of time Modified  Bitumen roofing lasts depends on many things.
What Is Modified Bitumen Roofing Material?
In asphalt, modified bitumen is made by combining the polymer with fiberglass or polyester reinforcement. This type of roof is made of an impermeable roof membrane. This type of roofing gives the roof better weatherproofing protection and durability than traditional asphalt built-up roofing (BUR).
Can You Bitumen Roof Repair?
When the modified bitumen coating is damaged, it can be repaired and controlled. The method of patching it is common.
Modified Bitumen Roof Replacement Cost
If you want to install a new bitumen roof over an existing roof, the Modified Bitumen Roof Replacement Cost can be $4 to $8 per square foot.
Modified Bitumen Roof Cost
The total Average Cost of a Modified Bitumen Roof from Basic to Best can range from 4.00 to $ 5.55 per square foot. The actual cost of bitumen roofing depends on factors such as the quality of the materials used, your location, the complexity of the installation.