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If you are looking to replace the roof on your home or business, it is essential that you choose the right material to suit your needs. There are several options on the market, so knowing the strengths and weaknesses of each will help you make an informed choice to ensure a long-lasting, high-quality shelter for years to come.

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What is Modified Bitumen Roofing?

Modified bitumen is a common flat-roof material that has been used since the 1970s. It is a roll of bitumen that has been modified with various other polymers to make it flexible enough to be manipulated. There are two different types of methods to apply modified bitumen roofing: hot and cold. Hot applications are generally not recommended due to the risk of fire when installing the roofing material.

Pros of Modified Bitumen Roofing

Despite its age, modified bitumen roofing is still commonly used in low-sloping roofs, due to its versatility and durability. It’s also quite popular in residential constructions, where it can resemble composite shingles, adding in aesthetic value.

Modified bitumen roofs have a proven track record of lasting up to 20 years or more. They have high tensile strength, so they can expand and contract without cracking, which is an excellent advantage if you live in an area with large temperature fluctuations and you’re worried about your roofing material breaking or degrading. Modified bitumen roofs are also highly weather-resistant, and can survive hailstorms with ease.

Other flat-roofing materials often come in sheets that then leave seams that can expand and leak. Modified bitumen seams can be melted together, creating a seamless roof structure that is impervious to water without being weakened over time. Modified bitumen roofs are also easy to repair since small patches can be applied and melted into the existing roof structure.

Cons of Modified Bitumen Roofing

Unlike EPDM roofing, which can be painted in a variety of colors, modified bitumen roofs are always dark, preventing them from reflecting heat. Instead, a modified bitumen roof will absorb heat from the sun, which can be advantageous in the winter, but troublesome in the summer. Unless proper insulation is installed, this could potentially lead to excessive heat in the interior of the building and higher energy costs to keep it cool.

Modified bitumen roofing materials are some of the more expensive types of roof to install, because only the 2- and 3-ply versions are suitable for long-term roof installations, as the 1-ply version tends to crack and degrade rapidly.

Modified bitumen also needs extra ingredients called granules to protect the roof from the sun; however, some installers don’t include these as part of their installation. The lack of granules can lead to quicker roof deterioration as well as increased heat production in the interior of the building.

Modified bitumen is also sensitive to water, and flat roofs tend to accumulate puddles. Modified bitumen isn’t recommended in wet climates due to its shortened lifespan and higher maintenance costs compared to other flat-roof material options.

Modified Bitumen Roofing Installation and Repair

There are various ways in which modified bitumen roofs can be installed, and the installation largely depends on the type of material used. SBS polymer-modified bitumen membranes can be installed with a cold adhesive or with a hot mopping of asphalt. APP polymer-modified bitumen is applied with direct welding and isn’t recommended for wooden buildings due to the inherent risk of fire. Our Polaris Roofing Systems experts will advise you on the best type of material and installation for your needs.

If you’re unhappy with your existing installation, our Polaris Roofing Systems consultants can advise you on the best option for modified bitumen roof repair that will extend the lifetime of your roof, prevent leaks and reduce energy consumption in the building.

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