How Much Does a Flat Roof Replacement Cost?

Homeowners' biggest concern about their upcoming flat roof replacement is how much it’ll cost. You’ll find plenty of content that makes getting a new flat roof look cheaper than it really is. 

But they only account for the material itself, which is only part of the equation. Then, it just gets confusing when they start mentioning individual prices for components, labor, and everything else. 

Well, this doesn’t answer the main question you’re looking for and muddies the water for no reason. 

For over 30 years, Bill Ragan Roofing has believed in providing upfront and transparent pricing. After all, how can homeowners feel comfortable spending their hard-earned money on anything roofing-related without clearly understanding the price?

So, let’s break down the general cost of a flat roof replacement per square foot and the cost based on the material.

By the end of this article, you’ll have the answers to the following questions:

• How much does a flat roof replacement cost?
• How much does a membrane flat roof replacement cost?
• How much does a metal flat roof replacement cost?
• What are the best roofing materials for a flat roof replacement?

How much does a flat roof replacement cost?

A flat roof replacement can cost anywhere between $4.50 to $17.00 per square foot. However, we need to look deeper into the type of material that’s being installed to narrow down where you’ll fit in the price range.

Let’s look at how much a flat roof replacement costs for roofing membranes and metal roofing. Just know that all the cost numbers are for an entire replacement project, including tear-off, materials, and installation (labor and time).

How much does a membrane flat roof replacement cost?

A flat membrane roof replacement costs around $12.00-$17.00 per square foot. You can opt for a modified bitumen roof for cheaper, but I recommend sticking with membrane roof systems. 

A membrane flat roof replacement is impacted by normal cost factors, like accessibility, replacing decking, number of penetrations, and the roofer you hire. However, two specific factors ultimately determine where you’ll fall in the price range.

The first is the type and quality of insulation installed underneath the roofing membrane. For example, insulating the entire structure with thick insulation boards costs more than gluing the membrane to fabric insulation. 

The second is the size of the flat roof, but it’s probably not in the way you think. The overall cost per square foot for smaller flat roofs will be higher, whereas the cost per square foot gets lower on larger flat roofing projects.

How much does a metal flat roof replacement cost?

A metal flat roof replacement will cost anywhere from $4.50 to $17.00 per square foot. This price is based on steel, so using a different type of metal changes the price dramatically.  

However, where you’ll fall in the range above depends on the metal roof system installed on the flat roof. 

A flat exposed fastener metal roof replacement costs around $4.50 to $7.50 on the high end per square foot. This metal roof system is the cheaper option, but the exposed fasteners require paying for routine maintenance to avoid leaks. 

On the other hand, you can expect a 24” gauge steel standing seam flat metal roof replacement to cost around $12.00 to $17.00 per square foot. Like the membranes, it could be more or less depending on the size of your flat roof, the number of penetrations, the roofing contractor you hire, and other factors. 

What are the best roofing materials for a flat roof replacement?

Now that you know how much a flat roof replacement costs, you need to make the right decision when choosing the roofing material. There are plenty of options, but there are four I recommend to homeowners.

Below are the best roofing materials for a flat roof replacement and how long they last. 

Standing seam metal roofing

While you can get either metal roof system, I recommend a standing seam metal roof. This is because its panels are locked together at the seams (ribs) or seamed mechanically so the metal can expand and contract freely. 

It's a great choice for a flat roof because of its multiple color options, durability, and long lifespan. However, you shouldn’t install a standing seam metal on a completely flat roof. 

Your roofing contractor must create some slope to provide drainage before installation can begin to avoid ponding water, which adds to the cost. There will also be some noise when rain hits the panels, but insulation boards help dull it out. 

A properly installed standing seam metal roof should last 30 years and potentially up to 50 years in ideal conditions.

EPDM membrane

EPDM (ethylene propylene diene monomer) is a synthetic rubber black membrane used mainly in commercial roofing. However, it’s become a popular option in residential roofing in recent years.

The only real downside to using a black membrane is that it makes the bedrooms or living spaces beneath hot during the summer months. There’s a white version out, but it gets dirty like the other white membranes.

Just consider the heat absorption for the room below when making your final decision. EPDM’s durability sets it apart from other membranes, with a fully adhered 0.060-thickness membrane lasting around 25 to 30 years.

PVC membrane

PVC (polyvinyl chloride) is a single-ply white membrane popular in both commercial and residential roofing. Unlike EPDM’s black membrane, the white reflects heat instead of absorbing it. 

PVC is a great option for living spaces or buildings looking for energy efficiency in the hot months. Just remember that white membranes get dirty over time, but keep in mind this has no impact on functionality. 

So, there’s no reason to worry about the look if aesthetics aren’t a big deal or you can't see it from a window. PVC isn’t as durable as EPDM, but it should still last around 25 years. 

TPO membrane

TPO (thermoplastic polyolefin) is a single-ply white membrane used in both commercial and residential roofing like PVC. They’re actually so similar that it takes a trained eye to tell the difference, with even the installation method being pretty much the same. 

The only big differences are their chemical makeup and it’s not as flexible as PVC. At this point you know the white membrane reflects heat, so it’s great over living spaces. 

Also, like PVC, a TPO membrane should last around 25 years as it’s installed properly.

How do you find a great roofing contractor for your flat roof replacement?

After reading this article, you now know how much a flat roof replacement costs and my recommended flat roofing materials as well as their lifespans. Remember to consider the room below the flat roof when making your decision. 

You should also discuss options with your roofing contractor because your area may be better for a specific type. However, you have to trust that the roofer is telling the truth.

Unfortunately, the roofing industry’s bad reputation was built on the backs of bad roofers. The last thing you want is to invest in flat roof replacement just to have it ruined by making the wrong hire. 

That’s why I wrote another article breaking down the tips you need to ensure you're hiring a reputable company in your area.

Check out 7 Tips to Find a Great Roofing Contractor to find a roofer you can trust with your flat roof replacement project.