Can a Metal Roof Be Installed on a Flat Roof?

Close-up detail of house roof made from gray metal sheets.

Metal roofing is becoming increasingly popular in residential roofing due to its versatility, durability, and aesthetic appeal. But can a metal roof be installed on a flat roof? This article will explore whether a metal roof is suitable for flat roofs, the types of metal roofing systems available, and the considerations you should take into account before making a decision.

Can You Put a Metal Roof on a Flat Roof?

Yes, you can put a metal roof on a flat roof. Installing a metal roof over a flat roof area, over a porch, or for other accent purposes is considered an upgrade. It’s quite common for homeowners to install a metal roof over their flat roof or low-slope roof. People choose metal roofing for its longevity, durability, and the sleek, modern look it provides, enhancing the home’s curb appeal.

However, it’s important to note that installing a metal roof on a flat roof can be more expensive than other options like membrane roof systems, which are also commonly used on flat roofs.

Is Metal Good for Flat Roofs?

Metal is a good option for flat roofs due to its durability and long lifespan. Metal roofs can last between 40 to 70 years with proper maintenance. They are also fire-resistant and can withstand extreme weather conditions. However, the success of a metal roof on a flat surface depends on the specific type of metal roof system used and the installation quality.

Can You Roof Over an Existing Flat Roof?

Yes, you can install a new roof over an existing flat roof. This process is called a roof overlay. However, whether you can do this depends on the condition of the existing roof. If the old roof is in good condition without significant damage like rot or mold, you can lay the new metal roof over it. This can save time and money on removal and disposal of the old roof.

When Should You Not Use a Metal Roof?

While metal roofs are versatile, there are some situations where they may not be the best choice:

  • Zero-Pitch Roofs: These roofs are completely flat with no slope, making them unsuitable for metal roofing because water can pool on the surface, leading to rust and damage over time.
  • Significant Structural Damage: If your current roof has severe damage, rot, or structural issues, it’s best to address these problems before considering a metal roof.
  • Budget Constraints: Metal roofs can be more expensive upfront compared to other roofing materials. If cost is a major concern, you might consider alternative roofing systems.

What Material Can You Put on a Flat Roof?

If a metal roof isn’t right for your flat roof, there are other materials to consider:

  • Modified Bitumen: This material is durable and relatively easy to install.
  • Built-Up Roofing (BUR): Consisting of multiple layers of bitumen and reinforcing fabrics, BUR is known for its durability and waterproofing qualities.
  • EPDM Rubber Membrane: This synthetic rubber roofing membrane is widely used for its flexibility and resistance to extreme weather conditions.

Can You Change a Flat Roof to a Sloped Roof?

Yes, you can change a flat roof to a sloped roof, but it’s a significant renovation that requires professional design and construction. This process involves building a new roof structure on top of the existing flat roof to create a slope, which can improve drainage and reduce the likelihood of leaks. However, this is usually an expensive and complex project.

Can You Use Metal Roofing on a Low Slope Roof?

Yes, you can use metal roofing on a low slope roof. Low slope roofs, which appear flat but have a slight pitch, are suitable for metal roofing. The slight slope helps with water drainage, reducing the risk of water pooling and subsequent damage.

What Is the Flattest Roof Pitch for a Metal Roof?

The minimum recommended pitch for a metal roof is 1:12, meaning the roof rises one inch vertically for every 12 inches horizontally. This slight slope is necessary to ensure proper drainage and prevent water from pooling on the roof surface.

Which Type of Metal Roof Is Best for Your Flat Roof?

There are two main types of metal roofing systems for flat roofs: standing seam and screw-down panels.

Standing Seam Metal Roof:

  • Description: This system consists of panels that lock together at the seams, allowing for expansion and contraction as the metal heats and cools.
  • Best Use: Recommended for flat roofs over heated living or workspace areas because it requires virtually no maintenance and accommodates thermal movement.

Screw-Down Metal Roof:

  • Description: Panels are screwed down directly through the metal, leaving no room for expansion and contraction.
  • Best Use: Suitable for non-heated areas or where budget constraints exist. However, it requires periodic maintenance to replace screws and prevent leaks.

How Much Will It Cost to Install a Metal Roof on Your Flat Roof?

The cost of installing a metal roof on a flat roof varies depending on the type of metal roof system, the size of the roof, and the roofing contractor. Generally, a screw-down panel metal roof starts around $4.50 per square foot, while a standing seam metal roof can cost between $12.00 and $15.00 per square foot.


Installing a metal roof on a flat roof is a viable option that offers many benefits, including durability, longevity, and aesthetic appeal. It’s essential to choose the right type of metal roofing system based on your specific needs and budget. While standing seam metal roofs are ideal for flat roofs over heated spaces due to their low maintenance and expansion capabilities, screw-down metal roofs can be a more affordable option with higher maintenance requirements.

If a metal roof isn’t the right choice for your flat roof, other materials like modified bitumen, built-up roofing, and EPDM rubber membrane are excellent alternatives. Understanding your options and consulting with a professional roofing contractor will help you make the best decision for your home or building.

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