A flat roof costs an average of $250 to $900 per roofing square (100 square feet), or $2.50 to $9 per square foot. These prices include roofing materials plus installation and labor. An average 2,000-square-foot flat roof would cost between $5,000 and $18,000.
Cost by Flat Roof Material
A flat roof’s cost per square foot depends on the type of material used. Below is the average price per square foot for common types of flat roofs.
Ethylene propylene diene monomer (EPDM) is a roofing material made from oil and natural gas. It’s easy to install, saving you money up-front, but the material fails after roughly 10 to 15 years. Black EPDM absorbs heat, reducing your energy bill. White EPDM often features a cooling laminate layer, but it typically costs more than black EPDM.
EPDM roofing costs $5 to $13 per square foot.
Fiberglass is an inexpensive, water-resistant, and sturdy material that lasts 25 to 50 years with proper maintenance. However, fiberglass is less durable than some materials, so annual inspections are recommended to ensure your home remains safe.
Fiberglass costs $4 to $6 per square foot.
GRP, or glass-reinforced polyester, is a newer, affordable roofing material. It’s a blend of plastic and fiberglass, offering increased durability and resistance to harsh elements. However, the material can be challenging to install and requires additional expertise. The contractor will also have to wait several consecutive dry days to install GRP, which may complicate scheduling.
GRP roofs cost $4 to $6 per square foot for installation.
Modified bitumen, or torch-down roofing, is a single-ply roofing material placed in sheets. Most roofers consider it easy to install, leading to low costs. It’s also fully recyclable. However, modified bitumen isn’t as water-resistant as other options, such as fiberglass, and it needs replacement after 10 to 20 years.
Modified bitumen costs around $4 to $6 per square foot.
Rubber flat roofs are highly resistant to warm weather and sunlight, making them an excellent choice for homes in sunnier climates. In addition, rubber is relatively lightweight and can last up to 50 years.
Rubber roofing costs $4 to $13 per square foot.
A tar roof, also called a built-up roof, has a lengthy installation process because it uses layers of gravel and tar built up over time. Tar roofs are highly resistant to fire and don’t require much maintenance, lasting up to 30 years. However, some roofers refuse to install hot tar roofs because most liability insurance policies don’t cover the job.
Tar roof installation costs $4 to $10 per square foot.
Thermoplastic Polyolefin (TPO)
Thermoplastic Polyolefin (TPO) is a single-ply roofing system that lasts between 20 and 25 years. TPO is lightweight and reflective, making it highly energy-efficient. Though it comes in several colors, white is the most energy-efficient.
TPO flat roofs cost about $3 to $5 per square foot.