Flat roofs are trending, and most homeowners love them because of their energy efficiency. This means with flat roofs, your home stays cooler in summer and warmer in winter. They can also be used for rooftop gardening, which adds to their popularity. However, they are not as durable as other roofs and can only last 15-20 years. This means your roof has to be replaced if the damage is beyond repair.
Usually, roof replacement costs $7,403 on average, but it may range anywhere between $1,200 - $24,000, depending on the style, size, and roof material. In this blog, we’ve broken down the cost so that you know how much of a budget you should keep at hand when replacing a flat roof.
How Much Does a Flat Roof Replacement Cost?
Here’s how much you can expect to spend on flat roof replacement -
Building Type
The cost of flat roof replacement also varies as per the type of building -
| Type | Cost Per Sq. Ft. |
| Residential | $5 - $17 |
| Commercial | $4 - $13 |
Roof Size
Considering the size of the roof gives you an estimate of how much a replacement may cost. Though it’ll give an approximate range, you can multiply the base of one wall with the base of another - this will give you a rough idea of the size of the flat roof. Here’s the breakdown of the cost based on the roof size -
| Roof Size (Sq. Ft.) | Average Cost |
| 1,000 | $4,000 - $14,000 |
| 1,500 | $6,000 - $21,000 |
| 2,000 | $8,000 - $28,000 |
| 2,500 | $10,000 - $35,000 |
| 3,000 | $12,000 - $42,000 |
Roof Type
There are several roof types that meet specific needs, such as -
| Roof Type | Cost Per Sq. Ft. |
| Cold Roof | $4 - $10 |
| Warm Roof | $8 - $12 |
| Inverted Roof | $5 - $10 |
| Hybrid Roof | $5 - $12 |
| Green Roof | $10 - $40 |
| Tapered Roof | $7 - $15 |
Application Method
There are several types of application methods depending on the type of roof you choose -
| Method | Cost Per Sq. Ft. |
| Ballasted Roof | $2 - $3 |
| Fastened Attachment Method | $2 - $3 |
| Full Adhered Method | $3 - $4 |
Roof Material
Here are the types of materials used for a flat roof, which may also affect the cost -
| Materials | Cost Per Sq. Ft |
| Metal | $4 - $30 |
| Modified Bitumen | $4 - $8 |
| Built-Up Roof | $4 - $10 |
| Rubber Membrane | $4 - $13 |
| Single-Ply Membrane | $4 - $7 |
| Thermoplastic Polyolefin | $3.50 - $14 |
| Fiberglass Or Glass Reinforced Polyester | $4 - $6 |
What Are the Factors Affecting the Cost of Flat Roof Replacement?
Understanding the cost per sq. ft., the size of the roof, and the type of materials available is a good start, but certain factors influence the flat roof replacement cost too, such as -
Drainage System
A proper working drainage system ensures that water easily drains off a flat roof, which keeps the roof in healthy condition for a longer time. Replacing or adding a drain may cost anywhere between $600 and $1,000.
Demolition and Preparing the Roof
The cost of demolition and removal usually ranges from $1 to $5 per square foot, averaging between $1,000 and $1,500. Preparing the roof includes clearing out the debris, addressing mold or algae, and repairing any existing minor damage.
Labor Cost
The cost of labor for a flat roof replacement may range between $40 and $80 per hour or $3 and $7 per sq. ft. If you live in urban areas, the cost may be higher. The time to install a flat roof may take 2-5 days, depending on the complexity and size of the roof.
Flat Roof Insulation
The cost of spray foam insulation might range from $1 to $5 per square foot. If you plan to incorporate rubber flat roofs, it may cost you around $01-$3 per square foot, along with installation.
Permits and Inspection
Depending on where you live, the cost of a permit for a flat roof replacement may differ. There may be a $25 application fee, in addition to a plan review fee equal to 20% of the permit cost, with a minimum of $25. The actual permit fee may be around $5 for every $1,000 of construction, with a minimum charge of $50.
How to Calculate the Cost of Flat Roof Replacement?
It is easy to determine the flat roof replacement cost. You can do this before reaching out to the contractors, as it will help you understand the fair pricing. Here’s how you can do it -
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Begin by measuring the footprint of the building and multiplying the length by the width.
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Since flat roofs have little to no slope, the answer you get will closely match the actual square footage of your roof.
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Next, multiply the answer by the average price of your roofing material choice.
It is advisable to add 10-15% to the total to avoid any unforeseen circumstances. Let’s put the above in numbers -
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30 by 50 food structure = 1,500 square feet
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Cost of EPDM = $8
Then the estimate would be = 1500 * 8 = $12,000. To this, add $1,200 - $1,500 more to be on the safer side.
Conclusion
The cost of the flat roof replacement may vary depending on the size of your roof, the material, etc. To determine the cost beforehand, you can use the formula given above, or you can directly get in touch with a professional roofer to help you with everything.
