Metal Roofs In DC – Part II

In a recent article, we took a look at some of the benefits and shortcomings related to corrugated panel roof systems. In most cases those types of roof systems cannot be used for low slope roofs, especially in climate zones like ours where freeze-thaw cycles are common.

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Today we’ll take a closer look at another alternative type of metal root system which is also generally made from metal materials. Materials of this type of standing scene Roof system can be aluminum, ferrous metals, and even semi-precious metals like copper. All of these types of roof systems can be found Here in DC, in standing scene roof assemblies. Only a few decades ago, it was more common to find ferrous standing metal roof systems in Washington DC. Today however many of those old roof systems have rusted through to the point that they had to be replaced. Once in a while, we still find them though.

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Standing seam metal roofs utilize vertical metal panels with raised seams connecting adjacent panels. These seams are elevated above the roofing material’s main near horizontal surface, providing an aesthetic appeal. These panels are commonly crafted from materials like galvanized steel, aluminum, or copper, which offer durability, resistance to environmental elements, and somewhat reduced upkeep requirements compared to modified bitumen smooth membranes.

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The standing seam metal roof systems rely on the raised seams to establish a connection between panels. Crimping tools secure these seams in place.  In most cases, this type of seam will keep most water out of the roof system, but in certain cases where the panels become partially submerged, the rolled or crimp sanding seams are not as effectively watertight as a fully adhered and fully welded seamed single-ply membrane.

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However, standing seam metal roofs exhibit certain limitations, particularly when contrasted with modern high-reflectivity polymer membranes like TPO (Thermoplastic Olefin). A prominent drawback lies in their compatibility with low-slope roofs. Stand sesm subsystems perform better on a configuration with steeper incline for efficient water drainage, rendering standing seam roofs less suitable for such applications. Low-slope roofs could potentially lead to water accumulation and subsequent leakage issues due to inadequate drainage, particularly in cases of ice-damming when there are occurrences of continued precipitation through and among repeating patterns of freeze-thaw cycles.

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In contrast, modern polymer membranes such as TPO are engineered specifically for low-slope roofing systems. TPO roofs offer exceptional reflectivity, reducing heat absorption and energy expenditures. Their robust weather resistance and flexibility enable them to accommodate structural movement without compromising integrity. Moreover, TPO roofs are often installed in a fully adhered manner, establishing a seamless and waterproof barrier.   Standing seam metal roofs lack many of these important beneficial characteristics.

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It’s accurate to acknowledge that standing seam metal roofs possess inherent advantages and disadvantages. While they boast durability and can have a substantial lifespan under proper installation and maintenance, their limitations in addressing water accumulation on low-slope roofs raise concerns.

The picture below shows two angles of a standing seam metal roof bending machine.  The machine operator feeds a flat metal coil, often made of materials like steel or aluminum, into the machine. This coil serves as the raw material for creating the individual roof panels.  The metal coil passes through a series of rollers, which gradually shape the flat sheet into the desired profile. These rollers are specifically designed to bend the metal without causing excessive stress or distortion.  As the metal sheet passes through the machine, additional components are used to create the raised seams. These components include stationary and moving parts that fold and crimp the metal along the edges.

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This machine uses an automated coil feeding system that regulates the speed at which the metal coil is fed into the machine. This system helps maintain consistent and accurate panel dimensions throughout the process.

metal coil

Choosing between standing seam metal roofs and modern alternatives like TPO hinges on several factors, including the roof’s slope, budget considerations, aesthetic preferences, and regional climate conditions. Both systems present distinct strengths and weaknesses, necessitating a thorough evaluation of project-specific requirements.

To summarize, standing seam metal roofs utilize raised seams for both visual allure and functional water drainage. However, their constraints on low-slope roofs and susceptibility to water-related challenges may outweigh their benefits. In most cases, especially on low-slope roofs, single-ply membranes such as TPO offer a more practical and effective solution. The selection of roofing material should be grounded in a comprehensive assessment of the project’s unique needs and priorities.

Smart proactive replacement, construction, upkeep and maintenance of low slope roof and mansard roof systems requires an enthusiastic interest and understanding of historical methodologies, waterproofing principles, and building science.   Here in Washington DC, historic and modern residential and commercial buildings are extremely expensive and the roof and related systems provide the shield that preserves the building. 

We encourage all of our clients, and all readers of this article and to our blog in general, to prioritize the value of quality construction and building maintenance, and develop a relationship with our company.  You can learn a lot more on our blog.  Feel free to check it out.  If you have questions about the roof and related systems of your building in Washington DC, contact us or fill out the webform below and drop us a line, it’s quick and easy.  We will be in touch if we can help.

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