Complete Guide to Flat Roof Replacement: Everything You Need to Know

It might be time to start considering a replacement if your flat roof is starting to show some obvious signs of wear-and-tear damage. Still, this might not be as easy of a decision as you’d think. The roofing industry is saturated with different roof types and materials, so it can be a bit tricky to navigate if you don’t have much experience with roofing.

Generally, the price to replace a flat roof is around $9,000 per 1,000 square feet. However, costs can vary, from as low as $4,300 to as high as $19,100. Factors that affect a flat roof’s replacement cost include the roof’s material, where you live and what your climate is like, and the amount of upkeep needed.

In our comprehensive guide, we’ll cover everything you need to know about a flat roof vs. a pitch roof, as well as the costs of repairs, replacements, and extensions of flat roofs. You’ll also get a breakdown of the most common materials for flat roofs, along with price estimates by square foot.

Let’s get started.

Flat Roof vs. Pitched Roof

Flat roofs and pitched roofs are two popular roof choices. But how do they differ?

While a flat roof refers to any roof without a peak, a pitched roof is one that does have a peak.

Let’s explore some key distinctions between a flat roof vs. a pitched roof.

Flat roofs, on the other hand, stand out from pitched roofs thanks to their more trendy design. A flat roof uses minimalist lines to offer a more modern look for businesses and residential houses alike. 

You’ll also face a lower price upfront. In terms of installation, flat roofs are much easier to construct compared to pitched roofs. When compared to pitched roofs, flat roofs don’t use as many materials. A flat roof is also simpler in its design.

Because they’re easier to install, flat roofs can also be built faster than pitched roofs.

Although people don’t agree on which type of roof offers the overall building more room, a flat roof does provide more usable space. To give you a visual, picture a pitched roof. Houses with pitched roofs usually have an attic that’s triangle-shaped. However, flat roofs typically allow the whole upper level to be the same shape and size of the lower level of a building.

Pitched roofs, on the other hand, are pretty common, as they’re about as traditional as they come. If you drive through a neighborhood, you’re most likely going to see many pitched roofs. For businesses, choosing a pitched roof over a flat roof can even make your business feel more “homey.”

A pitched roof also lasts longer. For example, if you choose a pitched roof made of asphalt, it could last two decades, or longer, depending. Factors that can affect a roof’s lifespan include the climate you’re living in, the material used to make the roof, and the maintenance needed. Either way, it’s generally considered a smart long-term investment.

Speaking of maintenance, though, pitched roofs usually require less upkeep. Instead of accumulating a build-up of snow or rainwater, precipitation glides right off of it. Because of their peak, these roofs are a bit more sturdy. The sloped design also allows for a smaller chance of a leak, and overall, leads to much less maintenance.

Pitched roofs also have better long-term value due to their minimal maintenance needs and longer lifespan.

Let’s take a look at the pricing for a flat roof replacement.

How Much Does It Cost to Replace a Flat Roof?

To replace a flat roof, expect to pay anywhere from around $13,500 to nearly $70,000. However, this can vary pretty wildly based on the materials used and the size of the roof.

If you’re evaluating based on the size, you can expect a flat roof replacement to run you anywhere from $4,300 and $19,100 per 1,000 square feet. This estimate includes both material and labor costs.

Below, you’ll find a table of prices for various sizes of square footage.

Building Space in Square FeetPrice Estimate

As you might expect, repairing a flat roof is cheaper, but the cost can also depend, based on the size of the repair.

How Much Does It Cost to Repair a Flat Roof?

Repairs for a flat roof will cost you less per square foot than it would to replace roofing. Expect to spend around $700. However, repairs on the higher end can run you over $1,000, though they can also cost as low as about $300, depending on the size of the repair.

Below is a table of example repair costs for a flat roof based on the repair size in square feet.

Size in Square FeetPrice Estimate
25$75 – $250
50$150 – $500
200$600 – $2,000
500$1,500 – $5,000

In addition to repairs, some homeowners make the decision to extend their roof for one reason or another.

How Much Does It Cost to Extend a Flat Roof?

To extend a flat roof, you can expect to pay anywhere from $1,000 to $20,000. The wide discrepancy is due to size variance. Flat roof extensions are priced by the size of the extension.

People get flat roof extensions for all sorts of reasons. You may want to extend a flat roof if you’re adding a room, like a bedroom or an office, or if you simply want to expand an existing room, like a kitchen, which is a common choice with regard to roof extensions.

Although size is a huge factor when considering the costs of repairing, extending, or replacing a flat roof, the actual material the roof is made out of also has a significant impact on the total price.

Flat Roof Price by Material

Flat roofs are crafted from a plethora of different materials. These materials include:

  • Metal
  • Fiberglass
  • Different kinds of rubber, including EPDM, PVC, and TPO
  • Modified bitumen
  • Build-up tar

We’ll provide an in-depth breakdown of flat roof prices made out of each material. Below, you’ll find a quick summary table of the flat roof price ranges by material type.

Material TypeCost per Square Foot
Metal$4 – $30
Fiberglass$4 – $7
EPDM$5 – $12
PVC$0.75 – $2.50
TPO$4 – $11
Modified Bitumen$3 – $6
Built-up Tar$3 – $8



With metal, expect to pay anywhere from as low as $4 to as high as $30 per square foot. Of all the materials, metal has the most dramatic price range due to the multitude of various metals you can choose to craft your flat roof from. That might be, in part, why metal is one of the most common materials used for flat roofs. The most popular metal used for flat roofs is aluminum.

The main benefits of a metal flat roof include its durability and sustainability.

Not only are metal flat roofs durable, but they’re also eco-friendly by reflecting heat rays from the sun. This means your energy costs are going to be lower.

Usually, metal roofing uses big sheets to cover large areas. However, this is also one of the negatives. It can be a bit difficult to work with if you have irregular areas or unique house features since the average metal roof sheet is pretty big. Still, it is possible to find smaller sizes to match these atypical aspects of your house.


Flat roofs that use fiberglass panels (also called skylight roofing panels) are pretty common. These panels are crafted from a durable polyester resin that’s then strengthened by fiberglass, hence the name.

On average, prepare to pay between $4 and $7 per square foot for a fiberglass flat roof.

Fiberglass flat roof panels are lightweight, translucent, and thin. That’s one of their main advantages: they let more light inside the house than with other flat roof materials, such as metal or build-up tar.

They’re also more durable than other roofing panels, like PVC. These fiberglass flat roof panels can also come as a heavy-duty option, which can put up with more severe weather. On top of that, fiberglass is low maintenance, simple to install, and also resistant to corrosion.

However, fiberglass flat roof panels do have some drawbacks. Over time, the panels will fade to a more yellow color. They also can’t be walked on, like some roofing materials can (for example, metal panels).


One of the other common flat roof materials is known as EPDM, which stands for “ethylene propylene diene terpolymer.” It’s a very strong synthetic rubber. To install EPDM, it can be mechanically attached, fully adhered, or even ballasted, meaning the roofing system’s seams will be secured by either special tape or liquid adhesives.

A flat roof made with EPDM will typically cost between $5 to $12.

This roofing material is pretty versatile, as it’s available in a plethora of different widths, has a few options for thickness, and comes in white and black.

EPDM has a lot of advantages. First, it’s pretty budget-friendly. It’s also eco-friendly, especially if you choose white as the color, since white reduces energy costs by reflecting UV rays. You might be surprised to know that EPDM is actually fire-resistant. Not only that, but this flat roofing material can slow the progression of a house fire, too.

The primary cons to EPDM flat roofs include its appearance and installation costs, along with its lifespan. For one, many people dislike the look of black roofs made out of rubber. It’s also more expensive to install. At the end of its life, it’s not uncommon for EPDM roofing panels to shrink, causing the membrane to stretch. This is known as “bridging.”


PVC (which stands for polyvinyl chloride) roofing makes use of single-ply white membranes.

Typically, PVC roofing will cost you between $0.75 and $2.50 per square foot.

A flat roof that uses PVC has a good number of advantages. For one, it’s extremely durable. It’s actually so resistant to water that the welded seams used creates a watertight bond. Believe it or not, that bond is tougher than the PVC itself.

PVC roofs also generally last around 20 years, which is a great lifespan with regard to roofing materials. They’re very resistant to the elements, including wind, water, and even fire.

PVC roofing is also sustainable, which is a great option for people with a more eco-friendly mindset. Lastly, it’s resistant to chemicals, too.

However, the main drawback is that with PVC, the entire old roof will have to be removed. PVC flat roofs will eventually degrade and once these panels become older, the repairs become more difficult, too.


Flat roofs made of TPO use a mixture of a few kinds of rubber — such as ethylene-propylene and polypropylene — as opposed to plastic. The thermoplastic polyolefin membrane (also known more colloquially as TPO)  is crafted with three layers. First, the TPO polymer base, followed by a polyester-reinforced fabric center called “scrim,” and completed with a thermoplastic polyolefin compounded upper ply.

Flat roofs made of TPO will cost anywhere from $4 to $11.

The advantages of TPO flat roofs include the simple installation, upkeep, and cost. Not only are TPO roofs easier to install, but they also don’t require as much maintenance as other roofing materials. That’s because with TPO membranes, things like dirt build-up, tears or punctures, and mold growth aren’t common.

They’re also pretty affordable, thanks to the fact that not only is the material inexpensive, but the installation isn’t very complicated, which can cut down on labor costs.

The main cons to using TPO for your flat roof include the wide range of quality and how new TPO is as a material. Unfortunately, not all TPO is crafted the same, and because of that, using TPO runs a risk of using a low-quality material. In addition, because this roofing material is so new, it hasn’t had enough time to prove itself.

Modified Bitumen

A modified bitumen flat roof uses either single or double-ply sheets of overlapping asphalt. The sheets are applied using heat, although some modified bitumen flat roofs use self-adhering sheets. 

For a modified bitumen flat roof, you’ll most likely pay about $3 to $6 per 1,000 square feet.

One of the best parts about having a flat roof made of modified bitumen is that you’ll need fewer layers than other materials that require layers. You can also cover this type of flat roof with a reflective coating, like metal roofs, to make it more weatherproof. They’re also very durable and pretty affordable for most people.

However, the main drawback to using modified bitumen as a roofing material is that the layers absorb heat instead of reflecting it, like metal roofs do. Modified bitumen is also harder to build.

Built-up Tar

A built-up roof (referred to as BUR) is a roof system that pairs layers of tar with synthetic (or natural) roofing. Sometimes, asphalt is used in place of the tar. Other times, instead of tar or asphalt, a reflective coating is used. Either way, the tar, asphalt, or reflective coating is applied when it’s hot before adding gravel to the top. 

 For built-up tar flat roofs, expect to pay anywhere from $3 to $8 per square foot.

Built-up tar roofs have a handful of pros, including their affordability, durability, and reliability. Roofs made of this material not only reflect sunlight and heat, as metal roofs do, but the gravel used in built-up tar roofs also protects all the other layers beneath it. As you might expect, the more layers a built-up tar roof has, the more durable it is.

The primary con of built-up tar roofs is that they can get pretty heavy. Although adding layers makes the roof more durable, the weight builds up.

At the end of the day, a flat roof replacement will cost you about $9,000 per 1,000 square feet, give or take. The factors that influence this price — your location, the company providing the replacement, the material, among others — are also critical to consider if you’re budgeting for a flat roof replacement.

One more quick tip: If you’re estimating the cost of a roof replacement, you might also want to consider other potential costs, including:

  • The initial inspection
  • A drain system installation
  • Roof sealant
  • Permitting
  • A roof vent installation

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