2023 Flat Roof Replacement Cost, Installation, Options

Average Roof Costs (1600 sq. ft.)
Most Homeowners Spent Between: Most People Spent: $7,650 - $9,500
Low End
High End

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Flat roofs are pleasing to the eye and space-efficient, but when it’s impossible to ignore or patch up the signs of aging anymore, it’s time to consider your flat roof replacement.

Are Flat Roofs Expensive To Replace?

The price for replacing a flat roof can vary greatly depending on several factors.

These include the size of the roof, materials, and location.

Flat roofs require specialized materials and replacing them is labor-intensive.

On average, flat roof replacement costs around $9,000 per 1,000 square feet.

This is for both the roofing materials and professional installation.

Average Flat Roof Replacement Cost

Replacing a flat-top roof can cost anywhere from $5,000 and $10,000 for a 1,000-square-foot flat roof.

This estimate doesn’t include the costs of repairing damage to the roofing structure underneath if any is present. 

However, for a more precise breakdown – materials for a flat roof can cost about $2 per square foot for the most economical ones, like rolled roofing, up to $15 or more per square foot for higher-end materials like PVC or metal.

Meanwhile, labor for flat roof replacement usually costs from $3 to $7 per square foot.

Local contractors can give you a more precise estimate based on their rates and an overview of the roof.

Cost of Replacing a Flat Roof on a 2,200-Square-Foot House

The price of replacing the roof on a 2,200-square-foot house can vary greatly but expect to pay between $11,000 and $22,000 in the lower-to-mid range.

This estimate includes materials and labor but not any possible repairs to the roof’s underlying structure if they prove necessary.

Average Flat Roof Replacement Cost Per Square Foot

Based on the total costs, the average price per square foot for a flat roof replacement ranges from $4.50 to $19.

The large range is partly due to the sheer number of options and the project’s complexity.

Also, the price per square foot doesn’t account for underlying repairs to the roofing structure.

Flat Roof Replacement Cost By Material

Different materials have different costs and durability.

They also vary in how much maintenance they need, which could affect your decision on what is really the most cost-effective.

Here’s the average cost per square foot for various materials (labor included):

Flat Roof Replacement Material Cost per Square Foot
Fiberglass $3.50-$7.50
EPDM $5-$11
PVC $8-$14.50
TPO $4-$14
Rolled Roofing $2-$3
Built-Up Tar (BUR) $3-$10
GRP $4-$6
Modified Bitumen $4-$8
Spray Foam $4-$13.50
Metal $5-$30


A fiberglass flat roof is relatively cost-effective.

More specifically, the total cost would be $3.50 to $7.50 per square foot.


There are different types of rubber roofing, such as EPDM (Ethylene Propylene Diene Monomer), PVC (Polyvinyl Chloride), and TPO (Thermoplastic Polyolefin).

EPDM is a low-cost alternative to PVC and TPO. It costs $5 to $11 per square foot.

A PVC roofing membrane can cost between $8 and $14.50 per square foot.

TPO (Thermoplastic Polyolefin) costs approximately $4 to $14 per square foot.

Rolled Roofing 

Rolled roofing is fairly cheap. It typically costs $2 to $3 per square foot.

Built-Up Tar (BUR) 

Costs for this material range from $3 to $10 per square foot.


GRP (Glass Reinforced Plastic) flat roofs are reasonably durable, affordable, and cost between $4 and $6.

Modified Bitumen

Modified bitumen costs approximately $4 to $8 per square foot.

Spray Foam 

Spray-on roof coatings can range from $4 to $7.50 per square foot for elastomeric acrylic coating and $7.50 to $13.50 per square foot or more for silicone.


Metal roofing is more expensive but one of the most durable, typically $5 to $30 per square foot depending on quality.

Pro Tip: Torch-down roofing is another roof replacement option. But it’s much more complex and dangerous because it needs a flame torch. It’s a solid option but not recommended to DIY-ers.

Flat Roof Replacement Cost By Type

The flat roof’s type is another variable in the total cost of installation (prices per square foot):

Flat Roof Type Replacement Cost per Square Foot
Cold $4-$9
Warm $6-$11
Inverted $4-$9
Hybrid $4-$11
Curved $8-$15
Tapered $7-$10
Green $10-$30

Cold Roof

A cold flat roof is typically more affordable as it requires less insulation.

It generally costs between $4 and $9.

Warm Roof

Warm flat roofs are more expensive due to the additional insulation required, but they offer more energy savings.

Their higher price range of $6 and $11 per square foot is made up for by the lower energy bills.

Inverted Roof

Inverted flat roofs, or “upside-down” roofs, are unique constructions that provides excellent insulation and protection for a price range of $4 and $9.

Hybrid Roof

Hybrid flat roofs, which combine the best elements of warm and cold roofs, can vary in cost depending on the design and materials, usually between $4 and $11.

Curved Roof 

Curved flat roofs are a premium complex construction with a unique aesthetic and cost from $8 to $15.

Tapered Roof

Tapered flat roofs can improve drainage but cost more due to additional materials and labor, specifically around $7 to $10.

Green Roof

A green roof can cost between $10 and $30 per square foot.

However, some designs might cost $50 or more per square foot due to the complexity and materials.

Flat Roof Extension Cost

A flat roof extension cost varies widely depending on size and construction.

A flat roof extension usually ranges from $80 to $150 per square foot for both materials and labor.

Additional Flat Roof Replacement Cost Factors

Several additional cost factors can impact how much you will be paying for the project by the end of it.

Additional Factors Cost
Drainage System $600-$1,000
Labor Costs $3-$7
Permits and Inspections $75-$450
Roof Removal $6
Roof Sealant $100-$2,000
Vent Installation $300-$400

Drainage System 

On flat roofs, drainage systems ensure that water can drain properly.

The drainage system may also need to go when replacing the roof. If so, a new one can cost $600 to $1,000 in total.

Labor Costs 

Expect to pay $3 to $7 per square foot for labor as a base.

Extra layers may run $1 to $2 per square foot.

Alternatively, some roofers charge about $40 to $80 per hour instead of per square foot.

Material Types 

As previously discussed, the roof material will significantly impact the total cost.

Each type has benefits and drawbacks, and the best depends on the budget and whether or not you’re staying at your current residence permanently. 

Cost Of Permits and Inspections 

Whether or not you need a permit or inspection to replace a flat roof depends on the location.

The cost of these permits also varies widely. It depends on the location, size, and complexity.

The permit price is often around $250; an inspection can run from $75 to $200.

Roof Removal

Removing the old roof is any roofing job’s first step.

A “tear-off,” as roofers call it, is usually a part of the average labor costs of around $6 per square foot.

Roof Sealant 

Installers should seal the new roof to protect it from climate damage.

Sealant costs vary wildly, from $100 to $2,000, depending on whether there are chimneys, skylights, or other roof elements the roofers need to seal.

Vent Installation Cost

Roof vents are necessary because they let air and rainwater escape from the roof.

Ventilation generally costs $300 to $400 for the entire system.

Did you know? Flat roofs aren’t actually flat. They slope slightly to one side (at least 1/4-in. per foot) to allow drainage. After heavy rain, puddles are inevitable. And the longer water stands, the more likely it is to find a way through the roof covering. So, if the flat roof were indeed wholly flat, this water wouldn’t have where to go and would cause mold and structural damage.

Flat Roof Replacement Process

The process of replacing a flat roof has several steps.

Let’s touch on them briefly using EPDM membranes as an example (for a more in-depth look, talk to a qualified professional):

  1. Removing the old roof involves removing the layers of felts, fabrics, and mats that make up the roof with a spade. 
  2. Removal of the perimeter framework – This is usually filled with mortar and can be removed with a firm tug or spade.
  3. Any pieces stuck to the brickwork’s surface need to be scraped off with a hammer and a bolster or wallpaper scraper.
  4. Installation of the new roof involves measuring the roof, selecting a right-sized membrane, and applying water-based adhesive.
  5. The other side of the matrix needs to be attached, and the membrane pressed down again to remove air bubbles.

Note that the roof can be a dangerous place to work. So you must ensure you’re standing on a supported part of the roof and not damage any parts while replacing it.

If you’re not absolutely confident in your skills, don’t attempt to do it alone but instead, contact a qualified professional.

What Are The Benefits Of A Flat Roof Replacement?

Replacing a flat roof has a few benefits:

  • Newer roofing materials are more durable and resistant to weather and wear than older ones. Beyond simply not being worn out, their engineering may have improved over time.
  • A new roof can make a property more valuable for those who might want to sell it.
  • Many modern roof materials are better insulators than older ones, which can reduce energy bills.
  • A new roof is less likely to need repairs any time soon, which also saves you money.

What Are The Most Common Problems Of A Flat Roof?

Flat roofs can develop some problems, such as:

  • Leaking and moisture are the most common issues with flat roofs. Water can accumulate on the roof and seep into the building if the roof isn’t sealed correctly.
  • Alligatoring is when the roof gets a cracked, bubble-like look that somewhat resembles alligator skin. It’s usually a sign that the roof is aging and worn out.
  • Buckling or warping can happen if the roof isn’t installed correctly or the building’s structure shifts over time.
  • Poor drainage is another standout problem. Flat roofs, despite the name, do need to have a slight slope so water can drain. If the drainage is inadequate, water can pool and damage the roof.

Pro Tip: Swift action can extend a roof’s lifespan. Inspect it often, maintain the drainage system, perhaps add extra waterproofing, and stay mindful of the environment. Look above the roof for tree branches that could scrape and damage it. Trimming back branches can prevent severe damage, even if a big storm hits.

Cost To Replace Flat Roof With Pitched Roof

Converting a flat roof to a pitched roof is a big project that can drastically change a home’s appearance.

The cost for this can range anywhere from $5,000 to $30,000.

It can cost even more, depending on how much the structure needs to change.

This estimate can include new support beams and joists, permits and inspections, extension of pipes, heating and air conditioning vents and ducts, and the chimney.

You’ll also need to account for the purchase of new siding to blend with the home’s existing cladding if the walls are going to be higher than they are now.

This is a significant construction project that can affect the architecture and stability of a home’s structure.

Therefore, working with a qualified contractor and possibly an architect or structural engineer will strongly benefit the home’s safety.

Is Flat Roof Cheaper Than Shingles?

Flat roofs can be less expensive to install than shingled roofs.

However, the total cost can be the same or even higher in some instances.

There are also long-term costs.

Flat roofs could need more maintenance and more frequent replacement than shingled ones.

Additionally, shingled roofs can’t be flat, requiring between a 1:6 (2:12) to 1:3 (4:12) pitch compared to the flat roof’s 1:40 or 1:80, so the structures and supporting elements are completely different.

Replacing a flat roof with a shingled one would require constructing a new roof.

Can Flat Roofs Be Repaired?

Flat roofs can sometimes be repaired with reinforcing tape.

Repairs are more cost-effective in many situations, but have diminishing returns.

If you have DIY experience and the damage isn’t too severe, you could try patching up a flat roof yourself.

However, if large sections of decking are rotted and need to be replaced, or if water pools in large areas, call a roofing company or general contractor for repairs.

Pro Tip: Local climate matters. Some materials perform better in certain climates than others. EPDM rubber roofing is resistant to cold temperatures, so it’s great for colder climates. On the other hand, PVC is heat-resistant, so it’s better for hotter climates.

How Hard Is It To Replace A Flat Roof?

Replacing a flat roof isn’t really for novices.

You’d need to remove the old roof, clean the area, cut and set reinforcing tape, and finally apply the new material.

It’s possible with some DIY experience to replace a flat roof yourself. But hiring a professional is generally better.

Improper installation can lead to leaks, damage, and more repairs.

Also, working on a roof can be dangerous if you don’t have the right safety equipment and training.

Can I Replace My Flat Roof DIY?

Replacing a flat roof requires specific skills and tools.

You could replace a flat roof as a DIY-er, but a professional installation is likely better.

Does A Flat Roof Replacement Require Building Regulations?

Replacing a flat roof requires compliance with local building regulations.

They mostly cover fire safety, insulation, and drainage.

Before starting a roof replacement project, check with a local building department.

What Is The Lifespan Of A Flat Roof?

A flat roof’s lifespan is hard to predict with certainty, but it depends on the material and installation quality.

Most flat roofs last between 10 and 20 years, but you can get a more precise quote from your contractor.

However, some materials, such as EPDM rubber or metal, can last up to 30 years or more with maintenance.

How Often To Coat A Flat Roof?

The frequency of coating a flat roof depends on the coating and climate.

As a broad estimate, it’s a good idea to coat a flat roof every five to 10 years to keep it durable and weather-resistant.

A more frequent coating may be necessary for harsh climates or roofs that get a lot of wear from weather or activities.

Is It Safe To Stand On A Flat Roof?

Standing on a flat roof is usually safe, but do it cautiously. The roof must be structurally sound and not slippery.

Wear non-slip footwear and be aware of hazards like loose materials or skylights.

Did you know? People usually associate flat roofs with commercial buildings, but they are becoming more popular for residential ones, especially the more modern ones. Their extra space can be convenient for solar panels, a rooftop garden, or even a rooftop patio.

How To Choose The Right Flat Roof?

There is no one single answer for “the one” roof that could fit any house. But your budget, location, and house design all come into play.

But here are some directions:

  • Your wallet is the deciding factor. Choose a material that fits it, but don’t ignore the long-term costs of maintenance and repairs.
  • Different materials fit different climates better. For example, EPDM rubber is resistant to UV radiation and is good for sunny climates, but perhaps not excessively hot ones.
  • A roof that complements the home’s overall style is a nice bonus. A modern home might suit a sleek, metal roof, and a traditional one might look better with a built-up tar roof.
  • Some materials, for example, EPDM rubber or metal, have a longer lifespan than others. It might be worth picking a more durable material if your budget allows it.
  • Some roofs need a bit more maintenance than others. If you’re unwilling or unable to do so regularly, go with a low-maintenance material.

Flat But Sturdy Roof

Replacing a flat roof can mean quite an expense, but it’s necessary occasionally to avoid serious problems like leaks or cracks.

But if you understand the costs and what can affect them, it’s easy to decide on the best way to accomplish this big project.

Average Roof Costs (1600 sq. ft.)
Most Homeowners Spent Between: Most People Spent: $7,650 - $9,500
Low End
High End

See costs in your area Start Here - Enter Your Zip Code

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