10 Types of Flat Roofs

Flat roof types

When you think of the word “roof,” pitched roofs with steep slopes are typically what comes to mind. A flat roof may not be the first style of roofing to pop into your head, but it is a good option with many benefits. And, there are 10 types of flat roofs to choose from.

Flat roofs are energy efficient, inexpensive, low maintenance, and easy to install. They are often used on commercial buildings, but they are also used on many modern-style homes. 

Each type of flat roof has its advantages and disadvantages, and each has its unique aesthetic. Nature lovers might prefer a green roof, while those looking for a cost-effective option might consider a rubber roof. 

What is a Flat Roof?

Some might assume that a flat roof is completely flat with no angle. This isn’t true. A flat roof is a low-slope roof tilted at less than 10 degrees. The reason flat roofs are set at a slight angle is to help with drainage. 

If a flat roof were completely flat, this would create a problem with ponding water on the roof. Water sitting on a roof will damage the roofing and cause leaks

10 Types of Flat Roof Materials

Even though asphalt shingles are the most common roofing material for pitched roofs, flat roofs cannot have asphalt shingles installed over them. Instead, there are many other types of materials used on flat roofs.

Built-Up Roofing (BUR)

Gravel roof
Photo Credit: Baloncici / Canva Pro / License

As the most common type of flat roofing, built-up roofing is a popular choice for homeowners. Known as tar and gravel roofing, this style of roofing has been used for over 100 years, making built-up roofing the oldest type of flat roofing. As the name suggests, BUR is built of layers of tar and roofing felt topped with several layers of gravel. Over time, the top gravel layer will show signs of wear and tear, and it can be replaced.


  • Low maintenance
  • Reasonably priced
  • Protects against UV rays
  • Waterproof
  • Fire resistant
  • Durable
  • Good insulation


  • Prone to leaks
  • Leaks are difficult to locate
  • Heavy roofing material
  • Not energy efficient

Lifespan: 15-30 years

Cost: $3-$8 per square foot (including labor)

Concrete Roofs

picture of a concrete roof in a diagonal pattern
Photo Credit: Dangphoto2517 / Canva Pro / License

While most people might think of sidewalks and driveway pavement when they think of concrete, concrete is also a roofing material. The material is a combination of sand, cement, and water. Concrete roofs are constructed of multiple layers: the concrete slab, the vapor layer, and the insulation layer, which is covered with polyurethane film. 


  • Low maintenance
  • Weather resistant
  • Durable
  • Energy efficient
  • Fire resistant
  • Long lifespan of 50 years


  • Porous substance that may be susceptible to leaks
  • Difficult to install

Lifespan: 50 years

Cost: $4-$8 per square foot (including labor)

Ethylene Propylene Diene Monomer (EPDM)

picture of a EPDM roof with mountains in background
Photo Credit: Doralin Tunas / Canva Pro / License

With a name that is difficult to say, ethylene propylene diene monomer synthetic rubber is one of the cheapest roofing materials on the market and the most common commercial flat roof materials. Rubber roofing such as EPDM lasts 10 to 50 years. EPDM roofing comes in either black or white, and the roofing material is held to the roof deck with either glue or fasteners. 


  • Inexpensive
  • Durable; not easily scratched or punctured
  • Easy to repair
  • Low maintenance
  • Lightweight
  • Recyclable
  • Fire resistant
  • Waterproof
  • Environmentally friendly
  • Good for cooler climates


  • Heat absorption increases home indoor temperatures
  • Heat absorption increases energy bill expenses
  • Requires a protective membrane to reflect the heat and UV rays

Lifespan: 10-50 years

Cost: $5-$12 per square foot (including labor)

Glass Reinforced Polyester (GRP)

Flat fiberglass roof
Photo Credit: Crownbuild / Wikimedia Commons / CC BY-SA 3.0

Glass reinforced polyester is a roofing material made of polyester and fiberglass. This single-ply laminate is used for other things such as boats and ponds. GRP panel roofs don’t do well with foot traffic, so limit walking on this type of roof as much as possible. 


  • Easy to install
  • Easy to repair
  • Low maintenance
  • Affordable
  • Durable
  • Weatherproof


  • Not good with foot traffic

Lifespan: 25-50 years

Cost: $4-$7 per square foot (including labor)

Green Roofs

A flat roof covered in plants
Photo Credit: Arlington County / Flickr / CC BY-SA 2.0

Appropriately known as living roofs or rooftop gardens, green roofs originated in Germany in the 1960s and consist of vegetative life planted in a growing medium on top of a waterproof membrane. They create a rooftop garden, perfect for plant-loving homeowners. Green roofs can be extensive, intensive, or semi-intensive, depending on how many plants — and how many big plants — you want for your green roof and what the structure can hold. 


  • Environmentally friendly
  • Reduces city heat
  • Provides cleaner air
  • Increases biodiversity
  • Manages rainwater
  • Reduces noise
  • Provides good insulation
  • Can be a recreational area


  • Expensive
  • Heavy roofing material
  • Roots can damage the roof
  • High maintenance
  • Leaks or other problems are different to detect and locate
  • Not well-suited for every climate

Lifespan: 40-50 years

Cost: $15-$50 per square foot (including labor)

Metal Roofs

Metal corrugated roof
Photo Credit: Prime Stock / Canva Pro / License

Not every metal roof is flat, but some metal roofs are flat roofs. Flat metal roofs consist of long metal sheets held down by fasteners or screws. Metal roofs can be made of aluminum, copper, steel, or zinc. 


  • Up to 100% recyclable
  • Reduces tear-off waste
  • Durable
  • Weather resistant
  • Low maintenance
  • Highly customizable
  • Lightweight 


  • Expensive
  • Prone to rust
  • Slippery surface
  • Prone to dents

Lifespan: 30-100 years

Cost: $3-$20 per square foot (including labor)

Modified Bitumen Systems (MBS)

Workers installing a modified bitumen roof
Photo Credit: Industrial Photograph / Canva Pro / License

Developed during the 1960s, modified bitumen roofs are one of the most popular flat roof types. The single-ply roofing material is often used for sheds. Sometimes referred to as mod bit, modified bitumen systems are made of tar (or asphalt) and fiberglass. Modified bitumen should be coated with elastomeric, a protective substance shielding the roof from the harmful UV rays. 


  • Flexible
  • Elastic
  • Adaptable to freezing temperatures
  • Repairs are generally easy
  • Lifespan of 15 to 30 years


  • Installation is difficult and labor-intensive
  • Punctures and tears easily

Lifespan: 10-20 years

Cost: $3-$6 per square foot (including labor)

Polyvinyl Chloride (PVC)

a picture of polyvinyl chloride rolls on ground
Photo Credit: Doralin Tunas / Canva Pro / License

PVC roofs, also known as vinyl roofs, are a type of thermoplastic waterproofing membrane. Since it is heat-welded at the seams, a PVC roof is less prone to leaks, durable and lasts longer than other flat roof materials. PVC is a single-ply membrane roofing material that is flexible and easy to install. 


  • Fire resistant
  • Wind resistant
  • Waterproof
  • Protects from UV rays
  • Chemical resistant
  • Resistant to wear and tear
  • Flexible
  • Easy to install
  • Strong


  • Reroofing isn’t an option
  • Does not do well in cold climates
  • Cost

Lifespan: 20-30 years

Cost: $6-$13 per square foot (including labor)

Spray Foam Roofing (SPF)

a person spray polyurethane foam on attic
Photo Credit: C12 / Canva Pro / License

Spray polyurethane foam roofing is installed in a strange but cool way: You simply spray the roofing material on. Spray foam roofing is applied as a liquid, which then turns into foam. Then the polyurethane foam hardens, creating the surface for your roof. Most commonly, a SPF roof comes in white or gray. 


  • Eco-friendly
  • Low maintenance
  • Waterproof and leak-resistant
  • Inexpensive
  • Self-flashing
  • Lightweight
  • Energy efficient


  • Protective outer coating must be reapplied every few years
  • Prone to damage from UV rays
  • Overspray during installation

Lifespan: 20-50 years

Cost: $4-$6 per square foot (including labor)

Thermoplastic Polyolefin (TPO)

Thermoplastic polyolefin is a lightweight rubber membrane that is installed in large sheets. TPO roofs can be glued to the roof or installed with fasteners to keep them pinned on the roof. It is a flexible material with a reflective, glossy surface. 


  • 100% recyclable
  • Eco-friendly
  • Lightweight
  • Flexible
  • Fire resistant
  • Protects from harsh weather conditions
  • Energy efficient


  • Not very resistant to cold conditions
  • Easily damaged
  • Surface prone to deterioration

Lifespan: 15-20 years

Cost: $4-$11 per square foot (including labor)

Pros and Cons of a Flat Roof

If you are considering installing a flat roof or buying a home with a flat roof, you want to know the benefits and downsides. Knowing the pros and cons of a flat roofing system is important to determine if a flat roof is right for you. 

Pros of a Flat Roof

From energy efficiency to aesthetic appeal, flat roofs have a lot of benefits to offer:

  • Usable roof space. Flat roofs can be used as recreational areas or as storage areas for HVAC units or ventilation systems
  • Low maintenance. Flat roofs usually need infrequent repairs and maintenance. They are easy to clean and upkeep, as they can be swept clean with a broom or leaf vacuum. 
  • Affordable. Flat roofs are one of the least expensive types of roofs, with installation prices ranging from $4,300 to $19,100. 
  • Quick installation. Most flat roofs are easy to install, usually taking roofers only one to two days to install. 
  • Accessible. Flat roofs are much easier to navigate than the steep slopes of a pitched roof. This makes them much easier to repair. 
  • Energy efficient. Flat roofs are equipped with great insulation, which keeps in both cool and hot air. This increases energy efficiency and decreases energy bill expenses. 
  • Curb appeal. Flat roofs offer a contemporary aesthetic that is suitable for modern buildings. 

Cons of a Flat Roof

Although flat roofs have many pros, no roofing is without its downsides. Some of the cons of flat roofs are:

  • No attics. While flat roofs can be used as a space for storing HVAC units, they come at the cost of no attic storage space. 
  • Drainage systems. Their drainage systems do not work as well as pitched roofs and they are more susceptible to water getting stuck on the roof.
  • Snow accumulation. With flat roofs, snow will keep piling up, which can be dangerous and put too much strain on your roof once the snow gets too heavy. 
  • Shorter lifespan. While some types of flat roofs have very long lifespans, certain types of flat roofing do not have a very long lifespan. Some only last around 10 to 20 years. 
  • Not ideal for cold climates. Most types of flat roofs are best suited for warm, arid climates. They don’t perform well in cold climates. 

FAQ About Types of Flat Roofs

What is the best color for a flat roof?

The best color for a flat roof depends on your personal preference. However, light-colored roofs are more eco-friendly and cost-effective, because white or light-colored roofs reflect the sun, which helps keep your house cooler. 

On the other hand, black or dark roofs absorb the heat from the sunlight, causing your roof and home to heat up. This will increase the amount of your energy bills. 

Will I damage a flat roof if I walk on it?

Most flat roof materials will not be damaged when you walk on them. There are two exceptions: glass reinforced polyester and thermoplastic polyolefin. However, wear and tear will occur over time if a roof receives a lot of foot traffic. When on a roof, always wear soft-soled shoes. Hard-soled shoes are abrasive and can damage your roof. 

How many times can you overlay a flat roof?

Usually roofs are allowed up to two layers before you need a full roof replacement, although it depends on the roofing material. Spray foam roofing can be applied over almost any flat roof material. Other materials, such as metal or green roofs, can have only a single layer. When they reach the end of their lifespan metal or green roofs have to be replaced. 

Ready to Get Your Flat Roof?

Now that you know the different types of flat roofs and the advantages and disadvantages of each type, it’s time to decide if a flat roof is right for you. 

If you’ve settled on a new roof type that works best for you or want to consult a professional, find a roofing contractor near you

Main Image Credit: sl-f / Canva Pro / License

Danielle Gorski

Danielle Gorski lives with her family in Texas. She has a degree in Professional Studies and a minor in marketing. Her hobbies include reading, drawing, and writing.