6 Reasons Why Commercial Buildings Have Flat Roofs

Published Categorized as Building Design
Gravel Flat Roof

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A flat roof is a type of roof that is almost level, with all the tiles or other coverings being parallel to each other. This type of design is common in business buildings.

The 6 main reasons why commercial buildings have flat roofs are:

  1. Flat roofs are cost-effective.
  2. They provide space for equipment storage.
  3. Flat roofs are easily accessible.
  4. They are quicker to install.
  5. Flat roofs are durable.
  6. Flat roofs are versatile.

Keep reading for detailed explanations of why building designers favor this roof design for commercial structures and insights into its disadvantages.

1. Flat Roofs Are Cost-Effective

Flat roofs are cost-effective because they don’t require expensive materials to build. They can be built with simple roofing shingles, tiling, or metal sheeting. This makes them much cheaper than pitched roofs that need more material to construct.

2. They Provide Space for Equipment Storage

Flat roof designs provide a great deal of space for equipment storage over the building, such as boilers, air conditioning units.

This is an efficient way to ensure optimum use of office space. Notably, businesses don’t have to spend more to rent bigger rooms since some of the equipment that would require large storage areas get installed on the roof.

3. Flat Roofs Are Easily Accessible

A flat roof design is more accessible than a pitched roof. This is more challenging with a pitched roof design as the slope makes it more difficult for people to climb up.

Notably, chances are higher of falling off a pitched roof than a level one due to the inclination on the former.

4. They Are Quicker To Install

Flat roofs require less time to repair since they have one surface area rather than having many different ones, such as sloping surfaces from high points down to low points. This also translates to lower labor costs.

5. Flat Roofs Are Durable

Flat roofs are more durable than pitched roofs for several reasons.

For example, they don’t have any high areas, so if anything leaks, it causes much less damage to other parts of the building.

Besides, these roofs are often made of sturdy, weather-and-corrosion-resistant materials like rubber, PVC, and bitumen.

6. Flat Roofs Are Versatile

Suppose you want to convert your commercial building with a flat roof design into one with an attic space. In that case, this will be quick and easy since no additional foundations will need installing.

Everything else can stay where it was.

Here’s a video that explains the pros and cons of flat roofs, as well as what to consider before installing them:

The Disadvantages of the Flat Roof Design

Although a flat roof design is cost-effective, quick to install, and offers space for equipment storage, it does come with some disadvantages.

Lack of Drainage

One disadvantage of a flat roof is that there are no gutters or downspouts, which means water can’t drain off the building quickly.

This could lead to an excess build-up on one side of the roof. If businesses are not careful about where rainwater pools, it may eventually leak into their offices through windows or other openings in the walls like doors.

They also need to take extra care when installing any electrical wiring because the moisture from leaks can damage them.

Debris Build-Up

Another downside to flat roofs is that they tend to collect debris and leaves. This happens because there’s one surface area for water to run off. This can cause problems unless the building’s owner uses some additional protection that covers the whole space.

Less Space for Insulation

The flat roof design provides less space between the floor and the roof. This means that there is less amount of air in the room just beneath the roof.

Since air is a good insulator, less of it means poor insulation in the room. Besides, the flat design means that the sun’s rays hit the roof directly, which causes flat roofs to absorb heat quicker.

Similarly, these roof types also get cold faster than pitched ones. Because of that, you may notice buildings with level roofs getting uncomfortably hot faster in the summer and colder in winter if HVAC systems are not installed in them.

Flat Roof Maintenance Tips

While flat roofs have a number of benefits compared to pitched ones, they still need maintenance.

Here are some practical guidelines on how to maintain a flat roof:

  • Repair any cracks that occur as soon as possible. If the cracks are deep enough that they can let in rainwater, you’ll also need to take steps for waterproofing, like installing a rubber membrane.
  • Flat roofs should be inspected at least once a year to identify deterioration or damage. It’s important to note that even a small leak can turn into a huge problem if it is left unattended.
  • Ensure the roof is covered with an anti-slip material like gravel or sand when it rains. Relatively high levels of moisture can make a flat roof slippery, so placing something that provides additional friction will help prevent accidents.
  • The materials used for flat roofs should be durable and sturdy enough to withstand the elements. As mentioned above, they are usually made of materials like rubber, PVC and bitumen.
  • Make sure that the roof is clean regularly to avoid debris buildup. This will help to minimize potential problems in the future.

FAQs About Flat Roofs

Are Flat Roofs Covered by Insurance?

Flat roofs are covered by insurance, but they’re more expensive to insure since there’s a greater risk for leaks. So long as they’re made from durable materials and properly installed, most insurers will cover flat roofs if they start leaking or get damaged by weather-related events. 

What Is the Best Material for a Flat Roof?

The best material for a flat roof is PVC roofing. It’s durable, fire-resistant, water-resistant, and waterproof. PVC roofs are one of the most flexible and structurally sound types of roofing materials on the market today.

For more information on the flat roof design, check out this Flat Roof Construction Manual by Klaus Sedlbauer (available on Amazon.com). The author explains the construction types as well as how to integrate flat roofs as circulation areas, green roofs, and solar roofs, making it an ideal reference to consider before embarking on installing this design.


By Giovanni Valle

Giovanni Valle is a licensed architect and LEED-accredited professional and is certified by the National Council of Architectural Registration Boards (NCARB). He is the author and managing editor of various digital publications, including BuilderSpace, Your Own Architect, and Interiors Place.

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