Modern exterior of luxury private house. Main entrance.

Flat roofs are an increasingly popular style for homeowners wanting a modern look. However, they offer several other benefits. Flat roofs also provide increased energy efficiency, easy maintenance, and more outdoor living space. 

The average cost to install or replace a residential flat roof is $5,000 to $18,000. Many factors determine where your roof’s price falls within that range. Our guide breaks down these factors to help you estimate your flat roof cost.



Pros and Cons of a Flat Roof

Before moving forward with a flat roof installation, consider these benefits and drawbacks.

Is cheaper than pitched roofsHas some drainage issues
Provides extra space for outdoor living and HVACIsn't ideal for colder climates
Is easier to install than other roof typesHas a shorter life span than some other roof types



Flat Roof Cost

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

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.



Other Factors That Influence Flat Roof Cost

Other factors beyond material can impact the cost of a new flat roof or replacement. Read more details below.


Labor costs roughly $40 to $80 per hour. A flat roof installation typically takes two to five days to complete. Labor costs can also vary depending on the installation’s complexity, such as if additional scaffolding or specialized equipment is required. 


As with many home improvement projects, areas with a higher cost of living come with higher roof installation costs. The weather in your area can also affect price, as you may need certain roofing materials to deal with specific climate trends. For example, if you live in an area that experiences severe weather, the roofing will cost more because the job requires better materials and more precision. Similarly, places that experience heavy rain or snowfall will require heavy-duty waterproof roofing.

Permits and Inspections

You’ll often need a building permit to replace your old roof with a flat one. Though you might be able to avoid this depending on where you live, these permits typically cost an extra $250 to $500. The price usually increases for roofs larger than 1,000 square feet. 

In addition, you’ll want to hire a contractor to conduct a final inspection after the roof has been installed. The same laws requiring a building permit typically require this inspection. A final flat roof inspection costs $100 to $300. 

Roof Removal or Repair

Flat roof installation often requires removing an old and damaged flat or existing roof. Roof removal costs around $1 to $5 per square foot. These costs can vary across contractors, so be sure to ask about removal pricing when evaluating a quote from your local roofing contractor. 

You may be able to save money by repairing an existing flat roof instead of installing a new one. Flat roof repair costs $4 to $9 per square foot for minimal damage. If too many layers of roofing are added to a roof, it can result in an excessive load on the roof, which may cause significant strain on the roof’s foundation and framework. In some regions, regulations require the removal of older roofing layers before adding new ones to prevent such an overloading situation, especially when there is heavy rainfall or snowfall that can increase the load on the roof. Speak with a roofing contractor to determine if this is an option.


Proper sealing is a vital part of flat roof installation. Sealant adds an extra waterproofing layer, makes the roof fire-resistant, and increases durability. However, including sealant increases the total cost by roughly $350 to $1,500.

Ventilation and Drainage

Flat roofs have drainage problems. If you already own a flat roof, you probably already have a solid drainage system. If not, you’ll either need to install additional roof drains or gutters, or reroute some of your preexisting drains. Drainage work adds an extra $500 to $1,200 to the project. 

Ventilation is also critical, as some flat roof materials can absorb heat, which is then released into your home. Installing a single roof vent costs $300 to $650 on average.



Contact a Professional

Flat roof installation is not a do-it-yourself (DIY) job. It requires expertise and knowledge, and the roof’s performance depends on proper ventilation and drainage. You’ll want to hire a professional rather than attempting the installation yourself.

Compare Quotes From Roofing Pros in Your Area
Find out how much your project will cost



Frequently Asked Questions About Flat Roof Cost



When to Consider a Broader Home Inspection

When purchasing or selling a home, it is critical to complete a thorough inspection to understand the condition of the property. A standard home inspection includes an assessment of a home’s systems and physical structure. After the process, the inspector will provide a report detailing their findings and recommendations.

If you are thinking about buying a home or putting your home on the market, we strongly recommend finding an ASHI home inspector in your area.