Bituminous Roofing System – Types, Advantages, And Disadvantages

What Is Bituminous Roofing?

Bituminous is a substance that is produced by the distillation of crude oil. It is a viscous (dense) and sticky material having adhesive properties. We can use bituminous as a waterproofing material in the roofing system.

The distillation process removes the lighter crude oil components like petrol and diesel, Retaining only heavier bitumen behind.

The more you refine the bitumen, you can achieve a better grade. Bitumen is composed of complex hydrocarbons and elements like calcium, sulfur, iron, and hydrogen.


How Bitumen Helps In Roofing

Bituminous roofing can be described as applying bitumen to a structure’s roof for waterproofing purposes, which prevents water penetration into the structure.


There are two types of bituminous roofing systems as follows:

  • Modified Bituminous
  • Built-Up Roofing

1. Modified Bituminous Roofing

This modified bituminous roofing system consists of a cap sheet and base piles which help to prevent water penetration. The cap sheet surfaces are modified with mineral granules to expand their weather ability. It is also known as the Modbit system in short.

This system utilizes granules and cool roof coatings to reflect the UV rays, which helps in increasing the durability of the roof and reducing building energy costs.


2. Built-Up Roofing

Built-up roofing systems have been in use for the long term due to their efficiency and reliability in preventing damages to the building’s interior or roof.

This system consists of alternating layers of membranes coated with bitumen and oxidized bitumen, generally known as Felt or ply sheets.

These ply sheets can be reinforced with rigid, stable, and high tensile strength fiberglass mats. The surface of the system can be coated or surfaced with aggregate to improve its waterproofing capacity.

Due to alternating layers of membranes, this system is more approachable for waterproofing and can last for a longer span. Under these systems, there are two main types of Bituminous membrane as follows. 

i) SBS Membranes

SBS Membranes are made up of bitumen modified with elastic Styrene-Butadiene-Styrene (SBS) polymers to form a “rubberized” bituminous coating.

This coating is applied to the reinforced fiberglass for high tensile strength and dimensional stability. Styrene-Butadiene-Styrene (SBS) members can be self-adhesive, but these are usually installed with cold adhesive or mopping asphalt.


II) APP Membranes

APP membranes are made with bitumen which is modified with plastic Atactic polypropylene (APP) polymer. That enhances the durability and toughness of the membrane.

This coating is generally applied to polyester mat and fiberglass products. Atactic polypropylene polymer (APP) is a torch(fire) used due to the high melt-ability of plasticized bitumen.

Reason To Consider Bituminous Roofing

1. High Resistance to Physical Damages

Bituminous roofing systems are suitable for areas with more hail storms or Nature waste from trees like fruits and branches falling.

The gathering of rainwater is not possible in a bituminous roofing system as it has a low slope that will run off the water.

2. Low Maintenance Roof

It is a one-time investment process and requires less maintenance cost in the future, only if it is installed in the correct procedure by the professionals; otherwise, it may cost you more.

3. Energy Efficient

Keeping the structure cool is the main priority in any construction; black absorbs the heat instead of reflecting it. So we must install a cooling feature with a thermal emission system on bituminous roofing.

Advantages Of Bituminous Roofing

Following are the advantages of Bituminous Roofing

  • Bituminous roofing can last for 20 years or more.
  • Most trusted method and has been in the market for a long time.
  • We can apply it in different forms such as self-adhesive sheets, cold-applied adhesive, or mopped asphalt as per needs.
  • The durability of Bituminous roofing is more when compared to other waterproofing systems.
  • The development of cracks is significantly less due to high tensile strength.
  • A bituminous roofing system can resist wind, fire, and storm, preventing damage.

Disadvantages of Bituminous Roofing

Following are the disadvantages of Bituminous roofing

  • Due to its black color, it absorbs the heat rather than reflecting it.
  • Additional coating with granules or cold roof coating is required.
  • The chance of heating the building is high if proper insulation is not done.
  • Bituminous roofing’s come in three-ply with certain cons.
  • Single-ply material is not durable; the two-ply and three-ply cost you more for installation.
  • The chances of bituminous roof damage are high if the roof holds or gathers rainwater.
  • Installation of bituminous roofing can cost you a lot.


As we know, structures are not easy to construct as they cost you a lot of money. To prevent damage to a structure, we must take certain measures, like following design rules, using standard quality material, and waterproofing the structure to avoid water penetration into the building structure.

These measures are one-time investments that can last for a longer duration. Failing to do so may lead to structural damages, and these damages can cost you more.

Also Read

Types Of Roofing Sheets
Types Of Water Proofing Membranes
Types & Methods Of Waterproofing
Types Of Roof Vents

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