Flat Roof Replacement Cost Per Square Foot

Flat roof replacement typically costs $4 to $9 per square foot for labor and materials, but installers may charge $250 to $350 per square instead. Each square equals 100 square feet. The install includes removal of a single layer of old roofing and disposal fees. Ventilation adds $300 to $600, while roof drains are $40 to $100 apiece. Extra underlayment could increase your total by $70 to $2,000.

Commercial

Commercial flat roofs cost $4 to $9 per square foot to install depending on the material. They are much bigger than residential roofs at 10,000 square feet on average. Expect to pay commercial roofers near you $40,000 to $90,000 for the complete removal of the old roofing and install of the new materials.

The materials used most often for commercial flat roofs include:

• EPDM: A synthetic rubber membrane that seals and waterproofs the surface
• TPO: Single-ply rubber blend with the ability to weatherproof the roof and reflect heat
• Modified bitumen: Waterproof asphalt-based sheets that bond to the roof using heat
• Built-up tar: Features several layers of roofing felt along with hot tar, fiberglass and gravel

New Flat Roof Costs by Type

Fiberglass Flat Roof Costs

A fiberglass flat roof costs $4 to $6 per square foot to install. Materials are about $1 per square foot but underlayment, vents and drains increase the total. This material is popular due to its low cost, supreme water resistance and 25- to 50-year lifespan.

Rubber Flat Roof Costs

Rubber flat roofs cost $4 to $13 per square foot. The price includes labor and materials. This type of roof resists sun damage, is lightweight and lasts up to 50 years with proper care.

EPDM

EPDM roofing is $5 to $13 per square foot, which includes materials and labor. This material is available in two colors — black and white. The white material costs 30 percent more and both can last up to 10 to 15 years.

Built-Up Tar

Expect to pay $4 to $10 per square foot to have a built-up tar roof installed. This type of roof is fire-resistant and easily lasts about 30 years.

GRP

GRP, or glass reinforced polyester, roofs are $4 to $6 per square foot for labor and materials. They feature a blend of plastic and fiberglass that withstands the elements. You can expect this material to last 25 to 50 years.

Modified Bitumen

Modified bitumen roofs are $4 to $8 per square foot. This flat roofing type is notable for its light hue that reflects heat and its 30-year lifespan.

Flat Roof Installation Cost

Contractors typically charge $3 to $7 to install flat roofs. This price includes removal and disposal of the old roofing. Expect to pay $1 to $2 more per square foot for the installation of additional roofing layers.

Flat Roof Material Prices

Flat roof materials are $1 to $4 per square foot. Fiberglass and GRP are the cheapest at around $1 per square foot. EDPM and modified bitumen cost the most at $2 to $4 for each square foot.

DIY Flat Roof Replacement vs. Hire a Pro

You should only attempt a DIY flat roof replacement if you have the time, tools and experience to get the job done right. Otherwise, leave it to the professionals since they can open up your roof without causing damage. They are also skilled in laying down the roofing materials so that they won’t leak in the near future.

Just make sure to find a licensed, bonded and insured roofing contractor with a great track record of success. Get quotes from at least three flat roof contactors near you to weigh your options. You’ll want to speak with their references and check out pictures of their past projects before selecting the best one.

FAQs

How do you maintain a flat roof?

The cost to seal the roof surface is $400 to $1,800 but it’s well worth the expense. The sealant creates a thick barrier that makes all the rest of your maintenance tasks a breeze. With that done, you just have to keep the gutters and surface clean plus check the flashing often for damage.

Clear the gutters after storms or at least every six months. Homes with many pine trees nearby may need their gutters cleaned every four months. In addition, it’s important to sweep off the roof periodically. Flat roofs are much more likely to collect leaves, dirt and other debris that can accumulate in piles and trap standing water, resulting in leaks.

Finally, be sure to inspect the flashing around chimneys and other roof joints for cracking. Apply caulk to the cracks or replace pieces of the flashing if necessary to prevent leaks.

How much do flat roof repairs cost?

Patching small tears and other minor flat roof repairs cost $300 to $600. Repairing storm damage, rerouting drains and other major overhauls could cost over $1,000. Remember to regularly take a close look at your roof for tears, holes and leaks. Promptly addressing these issues through DIY repair or by contacting a flat roof repair pro near you is the best way to extend the life of your roof.

What are the advantages and disadvantages of a flat roof?

Flat roofs are no longer just for commercial space. They have grown in popularity in recent years, and for good reason. Flat rooflines have a modern appeal that beautifully complements a wide variety of home designs.

Other benefits include:

• Better energy efficiency than traditional pitched roofs, according to Energy Star
• Much more versatile and easily transform into a rooftop patio or greenspace
• Completely safe to walk on when properly sealed and treated

Flat roofs do come with their downsides, however. For starters, they do not work on every home design, and installation and repairs are difficult to DIY. Also, flat roofs are not ideal for homes in colder climates with heavy snowfall. The low-grade slope may slow drainage, leading to pools of water and ice dams during the winter months.