Commercial Flat Roofs Still Require A Slight Pitch To Drain Adequately

If you look at most commercial buildings, you will notice that they have flat roofs. But flat roofs aren't entirely flat and instead have a slight pitch. 

Flat Roofs Aren't Completely Flat

Flat roofs have a slight slope so rainwater can drain off to one side. This prevents moisture from accumulating and causing problems such as dampness, rotting, leaks, and severe structural damage. A well-engineered flat roof has a slight slope.

Why Commercial Roofs are Mostly Flat

Compared with flat roofs, sloped roofs require more materials, labor, and engineering to cover a large surface area and to account for the weight distribution and wind resistance.

Flat roofs also offer some advantages over sloped roofs for commercial buildings, such as:

  • More usable space
  • Easier access and maintenance
  • Better visibility and safety

Flat roofs can improve the visibility and safety of a commercial building by reducing the risk of falling objects or snow accumulation on the roof edge. They can also reduce the glare and heat gain from the sun by reflecting more light than sloped roofs.

Why Drainage is Important

Drainage is one of the most critical factors for the performance and longevity of a commercial flat roof. Water accumulation causes problems such as:

  • Leaks and moisture damage
  • Ponding water
  • Ice dams

To prevent these problems, commercial flat roofs need adequate drainage systems to handle the amount and frequency of rainfall in the area. There are three main types.

Interior Drains

These drains are located near the center of the roof and connected to pipes that run through the building and out to the sewer system. Interior drains are practical for large roofs that have multiple low points where water can collect. They also prevent water from spilling over the roof edge.


These openings along the roof's edge allow water to drain off to a gutter or downspout on the exterior wall. Scuppers are suitable for roofs that have a slight slope towards the edge. They also provide a visual indicator of the water flow. They can prevent ice dams by allowing water to drain quickly.

Gutters and Downspouts

These are the most common drainage systems for residential roofs but can also be used for commercial flat roofs. 

Commercial flat roofs have a slight slope but are flatter than most residential roofs. However, they also require proper drainage systems. Therefore, when you have a commercial roof installed, you must consult with a roofing contractor about how you can ensure that your roof drains adequately enough.

Contact a local company to learn more about commercial roofing services.

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Spotting Roofing Problems Fast When you develop a roof leak, you don't have time to ignore it. Issues with leaks can cause problems as simple as incoming water and as wide-ranging as mold accumulation inside your home, which is why you should never let an issue sit. However, if you aren't careful, you could develop problems with roofing that is simply open to the elements, allowing rain and snow to enter your home, melt, and contribute to problems like mold growth. On this blog, you can learn more about the kinds of roofing issues that you could be faced with, and what to do about them.



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