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How much does a flat top roof cost?

Aug 16

Flat Roof Replacement Costs

Flat roof replacement costs between $3,155 to $10,239, or $6,676 per square foot, depending on the type of flat roof and whether vents, drains, and additional underlayment is required.

Flat Roof Replacement Costs Per Square Foot

A flat roof replacement typically costs $4 to $9 per sq. ft. for labor, materials, and labor. However, installers can charge $250-$350 per square. Each square is 100 feet. This includes the removal of an old roof and any disposal fees. The cost of ventilation is $300-$600, while roof drains can be $40-$100 each. Additional underlayment could add $70-$2,000 to your total.


Commercial flat roofs can be installed for $4-$9 per square foot, depending on the material. These roofs are larger than the average residential roof at 10,000 sq. feet. For the complete removal and installation of new roofing materials, expect to pay commercial roofers between $40,000 and $90,000.

These are the most common materials for commercial flat roofs:

  • EPDM: A synthetic rubber membrane that seals and waterproofs the surface
  • TPO: A single-ply rubber mix that can waterproof your roof and reflect heat.
  • Modified bitumen: Heat-resistant asphalt-based sheets that are waterproof and bond to the roof
  • Built-up Tar: This contains several layers of roofing felt, hot tar, and fiberglass, as well as gravel.

Flat Fiberglass Roofs Costs

Install a flat fiberglass roof; it will cost between $4 and $6 per square foot. The cost of materials is $1/square foot, but drains, vents, and underlayment will increase this figure. This material is popular because of its low cost and maximum water resistance. It also has a 25-to-50-year life expectancy.

Costs of rubber flat roofs

Rubber flat roofing costs $4-$13 per square foot. Prices include labor and materials. This roof is resistant to sun damage and lightweight. It can last up to 50 years if maintained properly.


EPDM roofing costs $5-$13 per square foot, including labor and materials. The EPDM roofing material comes in two colors: black and white. The white color is 30% more and can last up to 10 to 15% longer.

Tar built-up

To install a built-up tar roof, expect to pay between $4 and $10 per square foot. This roof is fireproof and lasts for about 30 years.


GRP roofs, also known as glass reinforced polyester, cost $4-$6 per square foot for materials and labor. The roofs are made from a combination of fiberglass and plastic that can withstand the elements. This material is expected to last 25-50 years.

Modified bitumen

Modified bitumen roofs range from $4 to $8 per square foot. This flat roofing material is known for reflecting heat and having a 30-year life expectancy.

Flat Roof Installations

For installing flat roofing, contractors typically charge between $3 and $7. This price includes the removal and disposal of old roofing. You will pay 1 to $2 more per sq. foot to install additional roofing layers.

Flat Roof Material Prices

Flat roof materials cost $1-$4 per square foot. $2-$4 per square foot.

DIY Flat Roof Replacement vs. Hire a professional

If you can use the right tools and experience, DIY flat roof replacement should not be attempted. If you don't have the time or tools to open your roof, a professional flat roof repair can do it. They're also proficient in laying the roofing materials to prevent them from leaking in the future.

Make sure you find a roofing contractor licensed, bonded, and insured. They have a proven track record of success. Get quotes from at least three flat roofing contractors near you to weigh your options. Before you choose the right one, speak to their references and see pictures from their past projects.