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Bitumen Roofing Materials & Cost Guide

For those who want a more durable, lower-maintenance roofing option, the modified bitumen roofing system is quickly becoming the most popular alternative for flat or low-sloping roofs. The modified bitumen roofing system was invented in Western Europe in response to a need for longer lasting roofs that were not prone to quickly drying out, as was the case with traditional asphalt shingles and sheeting rolls. After some years of experimentation, European scientists introduced the modified bitumen roofing material to the commercial market in the 1960s. This roofing system consists of layered bitumen membranes that are mixed with special polymers to give the roofing material properties akin to plastic or rubber.

The Costs 

  • Average minimum $2.73

  • Average maximum $5.21

Because of its initial cost and material properties, the modified bitumen roofing system was almost exclusively used for commercial and industrial roofing applications. For example, modified bitumen roofing solutions cost more than traditional asphalt roofing options, but it is well-known for its strength. Reputable manufacturers guarantee the useful life of the roofing systems up to 20 years when properly installed by a licensed roofing contractor. Over the years, advancements in technology and lean manufacturing methods have paved the way for lower production costs of modified bitumen roofing materials. These cost reductions have made the modified bitumen materials attractive for use in the residential roofing market. Homeowners whose residences have sections of flat roofs now consider modified bitumen roofing systems when it becomes necessary to update their roofs.

The cost of modified bitumen roofing sheets depends largely on geographic location and quality of materials. For example, the average cost quotes reflect the rates found on the international market. However, national markets may indicate costs that are up to three-times higher than those of the international market. Reasons for the disparity in costs include the availability of raw materials and manufacturing infrastructure. Another cost consideration is product quality; a cheaper cost could mean a lower-quality roofing material due to inferior raw materials or manufacturing practices.

In addition to the cost of the modified bitumen roofing sheets, those who install the material must have a building permit in most regions. This applies to those who are doing a complete roofing re-install. Usually a permit isn't required to simply replace small sections of a roof or lay modified bitumen membrane material over existing roofing materials. Modified bitumen roofing systems that require hot processing to secure the roofing sheets to the structure are generally installed by a licensed contractor who has experience working with that specific roofing material. Do-it-yourself roofing installations could save homeowners money. Self-adhesive, cold-processed modified bitumen roofing systems are typically used for these projects. The residential market for modified bitumen roofing materials is still not mature, and most of the big box home improvement stores do not yet carry the roofing materials.


The modified bitumen roofing system consists of six foundational elements.

  • Modified bitumen membranes

  • Insulation

  • Base sheets

  • Adhesive

  • Surfacing

  • Flashing

The modified bitumen membrane sheeting is the main element of the roofing system, and it is made from an infusion of polyester, fiberglass or a combination of both. The insulation layer provides its R value, or thermal resistance, that limits the movement of heat passing between the roofing structure. The base sheets build up the layers of modified bitumen for added durability and strength. The adhesive serves to attach the roofing material to the existing building infrastructure and gives it water resistance for protection against the elements. Surfacing is a compound that is applied either manually or via the manufacturing process to protect the roof against undue wear from ultraviolet light. Flashing is a material that provides additional waterproofing protection around a roof's perimeter as well as the gaps and seams found near roofing structures.

These materials are usually not readily available at the local hardware stores. To purchase modified bitumen roofing systems or the individual components described above, a reputable roofing materials distributor must be contacted. Although these organizations mostly deal with licensed contractors and provide them with discounts, they give price quotes and may sell the modified bitumen roofing products to the public.

Advantages of Bitumen Roofing

Modified bitumen roofing systems present real estate owners significant advantages for both commercial and residential applications. One such advantage is its longevity. Many traditional asphalt roofing systems experience problems after a 10- to 15-year period, but modified bitumen roofing systems are known to last over 20 years without a lot of maintenance issues. One of the main reasons for the long life of the modified bitumen roofing system is its strength; there are several types of modified bitumen roofing systems that use various polymer mixtures. Each type provides superior strength that contributes to the product's long wear and low-maintenance characteristics. Although modified bitumen roofing systems are known for their fantastic waterproofing properties, sometimes moisture can get under the bitumen membranes and base sheets to form bubbles. To correct this issue, the bubbles must be cut out and the area repaired with patch-sheeting material.

Besides its well-known properties related to material durability, the modified bitumen roofing system presents contractors with a variety of installation options. Some building owners can opt to invest in a professional installation that involves hot processing and guaranteed work. Other real estate owners can choose to install the modified bitumen roofing material themselves using the cold process method. Instructional materials are available for do-it-yourself roof installers who decide to use the self-adhesive version of the modified bitumen roofing sheets.

Disadvantages of Bitumen Roofing

One disadvantage of the modified bitumen roofing system is that it is only recommended for low-sloping roofs or flat roofs. This limits its application for use on non-factory roofs. Another possible disadvantage of modified bitumen roofing systems is its end-of-life environmental impact. The tough material lasts for years on one's roof, but it may also prove to do the same in the landfills.


When both commercial and residential real estate owners consider significant purchases such as a new roof, they often do a simple cost-benefit analysis of their available alternatives. While some would cite the modified bitumen roofing system's cost as a disadvantage, a closer inspection of the cost factors and benefits often shows the modified bitumen roofing system may be the better buy in the long-term.

Last updated on Jun 17, 2014

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