Flat roof systems are popular in Los Angeles and throughout Southern California. The low slope angle is just steep enough to drain rainwater while also being walkable, making access and maintenance easier. While they don’t use traditional tiles or shingles, several roofing material options are available for flat roofs.
The most common flat roofing materials are modified bitumen, EPDM membranes, and TPO membranes. Learn about each material’s characteristics, pros, and cons, and make the right choice for your building.
1. Modified Bitumen Roofing (MBR)
Modified Bitumen Roofing (MBR) is one of South California’s most common flat roof materials. It combines the durability and solar resistance of asphalt with the flexibility of polymer materials. The result is a flat roofing material that can be produced in layers and applied to a flat roof using the hot mop or torch-down techniques. The main differences between these two MBR flat roof installation methods:
- Hot mop roofing involves the application of multiple layers of materials. A flat roof specialist heats the bitumen material to about 400°F, then spreads it evenly on the roof’s surface using a specialized mop.
- Torch-down roofing uses a propane torch. Flat roof specialists heat up the underside of an MBR membrane before unrolling it on the flat roof’s surface. The heat partially melts the material, allowing it to stick to the roof’s surface evenly.
| Pros of MBR roofs | Cons of MBR roofs |
|---|---|
Durability. The asphalt materials used to build MBR layers are highly durable. They are safe to walk on and resist tears, punctures, and impacts. | Requires skilled contractors to install. Both MBR roof installation methods require using high-temperature tools operated by trained roof installation specialists. |
Flexibility. The polymer materials in the modified bitumen compound allow it to expand and contract with temperature changes. This helps preserve your roof’s integrity and protect it from wear and tear every season. | High initial cost. The cost of MBR per square roof depends on the roof’s square footage and the installation method used. They typically range from $2.75 to $7 per square foot. |
Easy to maintain. MBR flat roof repairs occasionally require a fresh layer of materials. Addressing cracks and tears is easy and cost-effective. | Limited aesthetic options. MBR materials have fewer color and style options than other flat roof materials. |
2. EPDM Membranes
EPDM (Ethylene Propylene Diene Monomer) is a synthetic rubber material fabricated into membranes widely used as a roofing material for flat roofs. An EPDM membrane is manufactured from three chemical compounds, each providing the membrane with a different property:
- Ethylene is one of the main components of an EPDM membrane, giving it flexibility and UV resistance.
- Propylene gives the EPDM membrane its overall elasticity, strength, and resistance to tearing.
- Diene binds ethylene and propylene, transforming the components into a single material. It also improves the membrane’s durability and resistance to chemicals.
Due to its high durability and UV resistance, EPDM is typically used on flat roofs that receive the most sun exposure, such as office buildings, apartment blocks, shopping centers, and warehouses. The material’s flexibility allows it to maintain its integrity with temperature changes, minimizing the risk of wear and tear.
| Pros of EPDM membrane roofs | Cons of EPDM membrane roofs |
|---|---|
Long lifespan. An average EPDM membrane roof can last up to 15 years with proper and regular maintenance. | Limited aesthetic options. Most EPDM membranes are available in black or white. While color EPDM membranes are available, fewer manufacturers offer them, potentially increasing costs. |
Low maintenance. EPDM roofs require less regular maintenance and upkeep than most other materials. | Vulnerable to punctures. Although EPDM resists general wear and tear, punctures can damage its surface, potentially exposing the roof to water damage. |
Easy to install. When handled by professional roofing contractors, EPDM membranes are relatively quick and easy to install. This can be beneficial if you need flat roof repairs or a quick flat roof replacement option. | Installation costs and roof complexity. The more complex and the more structures on your roof, the longer time it takes to install an EPDM roof. These factors can increase installation costs as professionals have to cut and apply layers of materials around each structure. |
3. TPO Roofing
Although they may appear similar to EPDM roofs at first glance, TPO roofs use a different material: thermoplastic olefin (TPO). Like EPDM, TPO is a roofing membrane that is particularly well-suited as a flat roofing material. It is commonly used to build roofs for apartments, commercial buildings, warehouses, condominiums, and schools.
TPO combines two materials: polypropylene (PP) and ethylene-propylene rubber. The combination produces a material known to be highly durable, flexible, and resistant to weather conditions.
| Pros of TPO roofs | Cons of TPO roofs |
|---|---|
Energy efficient. TPO roofing, especially white-colored membranes, is highly reflective of sunlight. This property allows the building to absorb less heat, cut cooling expenses, and meet California Cool Roof regulations. | Labor-intensive. Installing TPO roof membranes requires precise heat welding to ensure their integrity. This lengthy installation process demands skilled and specialized labor. |
Resistant to the elements. TPO is highly resistant to UV radiation, chemical exposure, environmental pollutants, wind, and rain. | Requires frequent inspections. While TPO is walk-safe and durable, it is more vulnerable to sharp objects than other flat roof materials. More frequent inspections are necessary to check for punctures and ensure water isn’t penetrating the membrane and damaging the roof. |
Cost-effective. TPO can be less expensive than many other flat roofing materials. The average price per square foot ranges between $3.50 and $14. | Limited color options. TPO membranes are typically available in white, gray, black, or tan. Colored versions are less available and cost more, limiting your aesthetic choices. |
Contact Roofing Professionals for Your Flat Roof
A professional roofing contractor should handle the installation, whether you choose modified bitumen, EPDM, TPO, or another material. They have the expertise to ensure your selected material is correctly applied to your roof, regardless of size and complexity.
Roofing contractors can advise on the best materials for your building, maximizing your roof’s durability and lifespan. They also offer regular maintenance and repair services to address wear and tear and ensure the roof’s structural integrity.
FAQs
Which material is the best for a flat roof?
The best material for your flat roof building depends on multiple factors: surface area, yearly exposure to the sun, number of roof-mounted devices, existing roofing materials, and your budget. A professional roofing contractor can evaluate your roof and provide an accurate quote.
What is the longest-lasting flat roof material?
EPDM membrane roofs can last up to 15 years with professional installation and regular maintenance. However, high-quality TPO membranes can last up to 30 years.
Are flat roof materials walkable?
Generally, yes, with considerations. While MBR, EPDM, and TPO roofs are all relatively safe to walk on, some materials may be more susceptible to tears and punctures from foot traffic. Consider reinforcing your roofs with walkway pads to extend their lifespan.
