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Flat roof replacement costs between $3,200 and $10,600, with an average cost of close to $7,000.* Flat roofs are an ideal choice for commercial buildings, but homeowners also would be wise to consider them. They’re more cost-effective than pitched roofs, related material and labor costs are lower, and they can increase the energy efficiency of a home. Below, we’ll cover flat roof installation costs to help plan for a roofing project.
*Cost data in this article was sourced from HomeAdvisor and Angi.
Flat Roof Replacement Major Cost Factors
Materials, roof size, and the cost to remove an existing roof dictate flat roof replacement costs. The average cost of flat roof materials and labor is $4 to $13 per square foot.
Roofing Material
Roofing material is a significant cost factor in a flat roof replacement. The quality of materials, durability of roofing, and complexity of installation will change the total cost.
Cost by Roofing Material
Fiberglass is typically the cheapest material to install, while metal roofs have the highest cost per square foot. Here are common flat roofing materials and how much they cost to install:
| Flat Roof Material | Average Cost Per Square Foot |
|---|---|
|
Fiberglass/GRP roofing |
$4–$6 |
|
Polyurethane roofing |
$4–$7 |
|
Single-ply membrane |
$4–$7 |
|
Concrete roofing |
$4–$8 |
|
Modified bitumen |
$4–$8 |
|
Built-up tar |
$4–$10 |
|
Rubber roofing/EPDM |
$4–$13 |
|
$3.50–$14 |
|
|
Metal roofing |
$4–$30 |
Roof Size and Complexity
The bigger the roof’s square footage, the more expensive the flat roof replacement. Larger roofs require more materials, labor, and time to complete, resulting in a higher price range. Roofs with complex architectural features, multiple penetrations, or unique designs may require additional labor, which will drive up the price.
Cost by Roof Size and Complexity
Here’s how much you might pay depending on the size of your home’s roof:
| Roof Size Per Square Foot | Average Cost Per Square Foot |
|---|---|
|
1,200 |
$4,800–$15,600 |
|
1,500 |
$6,000–$19,500 |
|
1,800 |
$7,200–$23,400 |
|
2,000 |
$8,000–$26,000 |
|
2,500 |
$10,000–$32,500 |
Removal and Disposal of Old Roofing
The number of layers a roofing contractor must remove from the old roof and the complexity of removal will impact what you pay. Many roofing contractors include “tear-off” in overall labor costs at $3 to $7 per square foot. Expect to pay $1 to $5 per square foot for removal, or an average of $1,000 to $1,500, if removal is priced separately.
Talk to your contractor about whether it’s possible to overlay the existing roof instead of ripping off the old one. This won’t be an option if your decking needs repair or your existing roofing structure can’t support the additional weight of added layers.
Professional vs. DIY Flat Roof Replacement
We don’t recommend do-it-yourself (DIY) flat roof replacement. Replacing a roof is dangerous and, if done incorrectly, can damage your home.
Professional Flat Roof Replacement
Roofing materials are heavy and require a team of experts to safely install, so we recommend hiring an experienced professional roofing company for a flat roof installation. Roofers charge around $40 to $80 per hour or $3 to $7 per square foot.
Roofers will inspect your roof before installation and prepare the property by dropping off materials, laying down tarps, and bringing a dumpster for the old roof. Next, roofers will remove your old roof down to the decking and inspect it for damage or structural issues. Roofers will prepare the roof’s surface and install a drip edge to prevent rain from getting underneath roofing components. Finally, roofers will install new underlays and new roofing material and finish it with a sealant.
Hiring a professional company comes with the following benefits:
- A crew and the equipment necessary to complete installation efficiently
- Experience to spot underlying issues that may not be obvious to the average homeowner
- Knowledge of required building permits, and the necessary licensing and insurance
- Warranties on materials or guarantees on their work
DIY Flat Roof Replacement
DIY roof replacement could save you on the cost of labor, but the cost of repairing a roof from water damage caused by improper sealing is significant. DIY roof replacement is dangerous and could void manufacturer warranties. Unless you’re a licensed professional roofer, we recommend you hire one.
Additional Factors Affecting Flat Roof Replacement Cost
Consider how these additional factors may affect your flat roof replacement cost:
Roofing System Complexity
The architectural complexity of your roofing system (variables such as multiple levels, slopes, or intricate features) can increase costs because they require additional labor and expertise.
Insulation and Underlayment
The type of insulation, quality of insulation, and underlayment materials required for flat roof replacement will impact the cost. Higher-quality insulation and underlayment, such as rigid foam insulation or specialized vapor barriers, are more expensive than standard materials. For example, fiberglass batting costs $0.30 to $1.50 per square foot, but you could spend up to $2 per inch of thickness per square foot of spray foam insulation.
Roofing Access and Safety Requirements
Accessibility affects replacement costs. If the roof is difficult to reach or requires special equipment, such as scaffolding or safety harnesses, it adds to labor and equipment costs. Adherence to safety regulations is necessary.
Warranty and Long-Term Considerations
Extended warranties on materials or workmanship will protect your investment but will also add to your overall cost.
Geographic Location and Market Conditions
Where you live impacts the cost of materials and labor. Some areas, such as California and Florida, have regulatory requirements that can increase the cost. Materials may be more difficult to procure in certain areas than others, and you may need to pay shipping costs.
Varying market conditions, material availability, and labor rates also influence the overall cost of flat roof replacement.
Drainage Systems
Adding or moving a drainage system to your flat roof costs $600 to $1,000, but flat roofs cannot properly function without one. Without a working drainage system, water on the roof could run down the sides of the home and damage the foundation.
Sealant
The application of sealant, which will cost $50 to $500, includes sealing the top layer of the roofing to block water and other elements from getting inside. If you have a chimney, skylights, or vents, the process will cost an additional $500 to $1,000.
Life Span of Flat Roofing Systems
The life span of flat roofing systems depends on maintenance, climate, whether the roofing was properly installed, and the type of material. The longer your roof lasts, the less frequently you’ll have to replace it, and the more money you’ll save.
The material also affects the life span of your flat roof. A fiberglass flat roof typically lasts 20 years or more, for example, while a zinc roof lasts 60 to 100 years. You can increase the life span of your roof by making regular inspections, checking drainage, and clearing the roof of debris.
How to Reduce Flat Roof Replacement Costs
Here’s how to save money on flat roof replacement costs.
- Get a quote from at least three roofing contractors that specialize in flat roof installation.
- Install your new roof over your existing roof if your existing roof is in good condition.
- Invest in higher-quality materials with a longer life span, which can save you on the cost of frequent repair and replacement.
- Regularly inspect your roof, and keep gutters and the roof’s surface clear of debris.
- Schedule work during the offseason.
How to Hire a Professional
Below are some tips to help you hire the right roofing contractor.
- Ask for references, and look at the company’s previous work.
- Check out the company on the Better Business Bureau website and read reviews on websites such as Trustpilot and Google Reviews.
- Get any cost estimates, guarantees, or warranties in writing.
- Get estimates from multiple contractors before making a decision.
- Make sure your contractor is licensed, insured, and bonded.
Our Recommendation
Roof replacement isn’t a DIY job, but there are ways you can save on flat roof replacement costs. Get quotes from multiple roofing companies, and ask if you can install your new roof over the existing one. Find a high-quality material that matches your budget and your style preferences. Keep up with maintenance so your new roof lasts as long as possible.
Flat Roof Replacement Cost FAQ
How does the cost of flat roof replacement compare to pitched roof replacement?
The national average price to replace a flat roof is $6,949. Flat roofs cover less surface area than pitched roofs, which reduces the cost of materials and labor. The size of your roof, the quality of materials, and the project’s complexity can increase costs.
Can I install a new flat roof over the existing one to save costs?
Yes, you can install a new flat roof over the existing one. This can save on the cost of removal and disposal of the old roof. This may not be an option if your roof is in poor condition or if your roofing structure cannot handle the extra weight.
How long does a flat roof replacement typically take?
A flat roof replacement takes professional roofers an average of five days to complete. The schedule ultimately depends on the size and complexity of the job. Some materials, such as built-up tar, are more time-consuming to install than others.
Are there any factors that can affect the life span of a new flat roof and its long-term cost-effectiveness?
Several factors affect the life span of a new flat roof. If your roofing material isn’t suitable for the climate in your region, its life span could be cut short. Proper installation and maintenance can also help extend your roof’s life.
Are there any government incentives or rebates available for homeowners considering flat roof replacements?
Traditional roofing materials don’t typically qualify for government tax incentives or rebates. Solar tiles and solar roofing may qualify for a tax credit. Other components, such as the roof’s decking or rafters, do not qualify for any credits.
