How Much Does It Cost to Repair a Flat Roof?

Average range: $250 - $1,000
Low
$50
Average Cost
$600
High
$5,000
(Fixing a leaky roof)

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How Much Does It Cost to Repair a Flat Roof?

Average range: $250 - $1,000
Low
$50
Average Cost
$600
High
$5,000
(Fixing a leaky roof)

Get free estimates from roofers near you
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Reviewed by Paula Reguero. Written by Fixr.com.

Flat roofs are commonly found on both commercial buildings and contemporary-style homes. Because there is little-to-no pitch or slope on a flat roof, they tend to develop issues relatively quickly, requiring repairs every few years. The most common issue with a flat roof is leaking, which may require a patch to correct the issue. But flat roofs can develop other issues, including alligatoring, blistering, bubbling, and sagging, with repair costs and methods varying accordingly.

The national average cost for professional flat roof repairs is between $250 and $1,000, with most homeowners paying $600 to fix a leaky flat roof. The low cost for this project is $50 for fixing a couple of cracked shingles. This project’s high price is $5,000 to tear off a large flat roof to prepare for a new one.

Average Cost to Repair Flat Roof

Flat Roof Repair Cost
National average cost$600
Average range$250-$1,000
Minimum cost$50
Maximum cost$5,000


Flat Roof Repair Cost by Project Range

Low
$50
Fixing cracked shingles
Average Cost
$600
Fixing a leaky roof
High
$5,000
Tearing off a large flat roof

Flat Roof Repair Cost per Square Foot

Roof repair specialists and companies usually decide how much to charge for their services based on the problem and the amount of repair work required. They take many factors into account, and they do not typically charge per square foot. However, the size of the damaged area can be an important factor. Expect to pay from $3 to $10 per square foot for professional flat roof repair. The table below shows the average repair costs for various roof sizes.


Cost to Repair a 50 Sq.Ft., 100 Sq.Ft., 150 Sq.Ft., or 200 Sq.Ft. Flat Roof

Cost to Repair a 50 Sq.Ft., 100 Sq.Ft., 150 Sq.Ft., or 200 Sq.Ft. Flat Roof


Roof Size Requiring RepairAverage Repair Costs (Labor Included)
50 sq.ft.$150 - $500
100 sq.ft.$300 - $1,000
150 sq.ft.$450 - $1,500
200 sq.ft.$600 - $2,000


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Cost to Repair a Flat Roof by Type of Material

One of the biggest factors influencing the cost of your roof repairs is the material your roof is made from. Roofs can be made from a wide range of different materials, including rubber, metal, concrete, and fiberglass 1. Some materials are easier and cheaper to work with and replace than others. The table below shows common roof materials and the average repair costs.


Cost per Sq.Ft. to Repair a Fiberglass, Modified Bitumen, Built-Up, Rubber, Concrete, or Metal Flat Roof

Cost per Sq.Ft. to Repair a Fiberglass, Modified Bitumen, Built-Up, Rubber, Concrete, or Metal Flat Roof


MaterialAverage Repair Cost per Sq.Ft. (Labot Included)
Fiberglass$3 - $7
Modified Bitumen$3 - $9
Built-Up$3 - $9
Rubber$4 - $10
Concrete$4 - $12
Metal$5 - $15


Fiberglass Flat Roof Repair Cost

Professional repairs for a fiberglass roof cost between $3 and $7 per square foot. Fiberglass is one of the most affordable materials for a flat roof, and they are made with plastic strands woven together into a strong mat, covered with special protective coatings. While fiberglass roofs withstand general weather conditions and wear and tear, they tend to crack, break, and dent easily. They are also very susceptible to water damage.

Modified Bitumen Flat Roof Repair Cost

Repairing a flat roof made of modified bitumen 2 averages $3 to $9 per square foot. Modified bitumen is a popular, affordable material for flat roofs, well-known for its versatility and resistance to extreme temperatures and UV rays. However, modified bitumen roofs are at risk of damage due to debris and impacts from hail and falling tree branches. Pooling of water on a modified bitumen roof can also make it wear down quickly.

Built-Up Roof (BUR) Repair Cost

Fixing a built-up roof ranges from $3 to $9 per square foot. Built-up roofs are similar to modified bitumen roofs and have the same pros and cons. They are affordable, versatile, and easy to install, but they can be prone to impact, storm, and water damage if water pools on top for too long.

Flat Rubber Roof Repair Cost

Repairing a flat rubber roof costs between $4 and $10 per square foot. Rubber is a popular material to use in constructing flat roofs because it is lightweight and can withstand sun and water damage. However, a flat rubber roof can split or crack over time, especially with exposure to extreme temperature and weather conditions, and these splits need to be patched and resealed.

Concrete Flat Roof Repair Cost

Expect to pay between $4 and $12 per square foot for concrete roof repair. Concrete is one of the strongest materials used for a flat roof, being completely water and weather-resistant. However, cracks and fissures may appear in a concrete roof over time and need to be filled in to prevent water from penetrating or ice freezing inside the gaps.

Flat Metal Roof Repair Cost

Metal roof repairs average $5 to $15 per square foot. Various materials are used in metal flat roofs, including aluminum and steel, and metal roofs are known for their strength and solidity, lasting decades with minimal maintenance. However, changing temperatures can cause the fasteners 3 and parts of a metal roof to expand and contract, potentially leading to pieces falling out of place or suffering damage that requires repairs.

Cost to Repair a Flat Roof by Type of Repair

Many different issues may arise with a flat roof, and the costs of flat roof repair are highly dependent on the problem and repair required. Some repair jobs are quick and simple, requiring minimal work, while others are more extensive and difficult, tending to cost more. The table below shows flat roof repairs and average costs for each.


Cost to Repair a Flat Roof by Type of Repair: Snow Removal, Flashing, Debris Removal, Drain, Shingle, Seam...

Cost to Repair a Flat Roof by Type of Repair: Snow Removal, Flashing, Debris Removal, Drain, Shingle, Seam...


Type of RepairAverage Repair Costs (Labor Included)
Shingle$50 - $800
Drain$75 - $300
Drip Edge$150 - $400
Seam$150 - $500
Flashing$200 - $500
Membrane$200 - $1,500
Debris Removal$250 - $600
Snow Removal$300 - $700


Flat Roof Shingle Repair Cost

Flat roof shingle repair averages $50 to $800, depending on the number of damaged shingles and required repair work. Most flat roofs do not have shingles because shingles are usually only installed when a slope is present. However, there are cases where certain areas of a flat roof can have shingled sections. Shingles may get cracked, split, or broken and could need to be treated with adhesive or patching materials to repair them.

Flat Roof Drain Repair Cost

Flat roof drain repair costs between $75 and $300. The drain is an important part of the overall flat roof design, helping drain water away and preventing it from pooling on the roof and damaging the roof materials. Unfortunately, drains can clog, so they may need to be cleaned out. They may also become damaged and cracked in storms or extreme temperatures, so they might need patching or parts replaced.

Flat Roof Drip Edge Repair Cost

Repairing flat roof drip edges ranges from $150 to $400. Drip edges are L-shaped metal pieces positioned at the edge of the roof. They can also be known as drip edge flashing and are used to divert water off the roof, away from any fascias, preventing it from pooling under the roofing materials. Metal drip edges are strong, but they become dented or damaged in storms or because of falling debris. So, they may occasionally require patching or cleaning.

Flat Roof Seam Repair Cost

Expect to pay from $150 to $500 for professional seam repair on a flat roof. The seams of the flat roof can be its weakest point. This is where different sheets of material meet or roof parts connect. It is common for water to penetrate these areas more easily than other parts of the roof, potentially causing leaks and other damage. Seams may need to be treated with adhesive or sealing materials to repair them.

Flat Roof Flashing Repair Cost

Repairing flat roof flashing costs $200 to $500. Flashing is a thin metal material used to seal the edges of the roof and prevent water damage. It is usually made from steel, copper, or aluminum and resists water and weather. However, it naturally wears down over time or may become damaged due to impacts in storms.

Flat Roof Membrane Repair Cost

Professional repairs for flat roof membranes average $200 to $1,500. The membrane of a flat roof is the material that keeps water out, and this can include rubber, modified bitumen, and similar materials. Membranes can suffer from holes, cracks, blistering, alligatoring, and other problems over time, usually due to excess water and difficult weather conditions.

Roof Debris Removal Cost

Debris removal from a flat roof costs between $250 and $600. Since these roofs are flat, there is more risk of dirt and debris piling up on top of them, rather than rolling down and falling off the sides like on a sloped roof. Therefore, it is important to have debris removed from your flat roof, for aesthetic and protective reasons, because too much dirt and debris could lead to the roofing materials wearing down more quickly.

Flat Roof Snow Removal Cost

Snow removal for a flat roof averages $300 to $700. Snow can pose a big threat to flat roofs. As it builds up slowly over time, there is no slope to help it fall off the roof. As the weight builds up, pressure on the roof rises, and the roof may begin to sag. There is also a risk of ice dams, leaks, and other snow-related damages, so it is vital to clear snow pile-ups from any flat roof.


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Cost to Repair a Flat Roof by Type of Problem

Many different problems affect flat roofs, and most are caused by weather and temperatures. Others can be caused by accidents, impacts, or general wear and tear. The repair method depends on the problem. Fixing a leak is very different from dealing with a sagging roof, and the costs vary accordingly. The table below shows common flat roof issues and average repair costs for each.


Cost to Repair a Flat Roof by Type of Problem: Leak, Water Pooling, Hail Damage, Blistering, Alligatoring, Sagging...

Cost to Repair a Flat Roof by Type of Problem: Leak, Water Pooling, Hail Damage, Blistering, Alligatoring, Sagging...


Type of ProblemAverage Repair Costs (Labor Included)
Water Pooling$75 - $300
Hole$100 - $1,000
Crack$150 - $1,250
Blistering$250 - $1,000
Alligatoring$350 - $1,000
Leak$400 - $1,000
Hail Damage$700 - $4,000
Sagging$750 - $2,000
Tear Off$1,500 - $5,000


Water Pooling on a Flat Roof

If you have water pooling on your roof, expect to pay between $75 and $300 to fix it, depending on the problem. This is when small water puddles or pools form on your roof. It usually occurs when water does not drain properly. This may happen because the drain is clogged or broken, so you might need to have the drain repaired, replaced, or cleaned out. Water pooling in other areas could signify bigger issues, like sagging, which leads to even higher costs.

Hole in a Flat Roof

Fixing a hole in a flat roof costs from $100 to $1,000, depending on the hole size and the work required to repair it. Small holes can be patched or filled in quickly, but larger holes require extra work and materials, leading to higher repair prices.

Flat Roof Crack Repair Cost

Fixing a crack in the roof ranges from $150 to $1,250, depending on the crack size and materials used. Cracks can occur in many roofing materials, including concrete and fiberglass, and if left alone, they can become bigger, wider, and more likely to lead to leaks and extra damage. Repairmen can usually fill in cracks or patch over them.

Flat Roof Blistering

Expect to pay between $250 and $1,000 for blistering repair. This is basically the same thing as bubbling. When little pockets of air or moisture become trapped between the layers of membrane on the roof, little bubbles or blister-like lumps appear in the membrane. If left alone too long or exposed to heat, these blisters eventually expand and burst, exposing the more fragile parts of the roof below and resulting in cracks and tears on the membrane. They need to be resealed or covered with a fresh membrane material.

Flat Roof Alligatoring

Repairing alligatoring on a flat roof costs between $350 to $1,000. Alligatoring is when the roofing material ages and starts to crack and crease over time, taking on the appearance of alligator skin. This can be unpleasant aesthetically and risky for safety reasons because roof materials that show alligatoring signs are more likely to rip, tear, and leak. The solution is usually to patch the area with a new piece of membrane or material, but sometimes, you can cover the affected area with a sealant.

Flat Roof Leak Repair

The average cost to repair a leaking flat roof is between $400 and $1,000. Leaks are usually the biggest cause for concern for homeowners with flat roofs because water entering the home can do substantial damage and needs to be dealt with quickly. Leaks may be caused by issues with the seams, rips, or tears in the membrane or holes and cracks in the roof material. To fix them, repairmen usually need to patch or seal the affected area.

Flat Roof Hail Damage

Repairing hail damage to a flat roof averages $700 to $4,000. Hail damage is a concern for flat roof owners because hail can damage the membrane and other parts of a flat roof, potentially leading to dents, rips, holes, tears, and leaks. In the worst cases, huge sections of the roof might need replacing.

Flat Roof Sagging

A sagging flat roof costs between $750 and $2,000 to repair. Sagging is a worrying sign in a roof because it shows that the actual framework or structure of the roof is under threat. This may happen for various reasons, such as water damage to the deck or buildups of ice and snow putting too much weight on the roof. Only small sections need repairing in minor cases, but if large parts of the roof are affected, repair costs can be very high because new structural beams are needed.

Flat Roof Tear Off

Tearing off a flat roof ranges from $1,500 to $5,000, depending on the roof material and size. Large roofs require more work, so the price is higher. The tear-off process involves removing the existing roof, getting rid of the old materials and membranes to prepare the space for installing a new roof. This can be the correct option if you are worried about weight, but sometimes it is better to get the new roofing material installed on top of the existing one, instead of tearing it off.

Cost to Repair a Flat Roof by Method

A range of different methods may be used to repair your roof, depending on the issue. When holes and cracks appear, patching and resealing may be necessary. Resurfacing might be required for situations involving alligatoring and blistering. Costs vary, depending on the method, and the table below shows common repair methods and average prices for each.


Cost to Repair a Flat Roof by Method: Patch, Paint, Reseal, Resurfacing, Torch Down, or Insulation

Cost to Repair a Flat Roof by Method: Patch, Paint, Reseal, Resurfacing, Torch Down, or Insulation


MethodAverage Costs (Labor Included)
Patch$100 - $1,000
Paint$150 - $700
Reseal$150 - $1,000
Resurfacing$250 - $1,000
Torch Down$350 - $3,000
Insulation$500 - $2,500


Flat Roof Patch Repair Cost

The average cost for patching a flat roof is between $100 and $1,000. Patching is one of the most common forms of roof repair and is used to deal with issues like small cracks and holes in the roof. It can be a cheap and simple method to cover up small damages and prevent them from getting worse.

Flat Roof Painting Repair

Painting a flat roof averages $150 to $700, depending primarily on the roof size. Larger roofs require more work and paint, so they cost more to cover completely. Given that some flat roof materials are dull or not very aesthetically appealing, some homeowners and building owners like to paint them to improve their appearance.

Reseal a Flat Roof

Expect to pay between $150 and $1,000 for resealing a flat roof. Resealing can be an important process if the existing seals are damaged or worn. Sealing is vital to prevent water from penetrating the roofing materials and getting down to the deck or into the home or building.

Flat Roof Resurfacing

Professional flat roof resurfacing ranges from $250 to $1,000, depending on the size of the affected area and amount of resurfacing required. Usually, resurfacing is the go-to repair method when roofs are old and suffering from issues like blistering and alligatoring. Resurfacing helps cover damaged areas with fresh materials, giving new life to older roofs.

Torch Down Roof Repair Cost

The cost to torch down a roof is between $350 and $3,000. Torch down roofing uses a blowtorch to seal the layers of roofing materials together, including asphalt, gravel, bitumen, and fiberglass. Torch down roofing can be very strong and resistant, so it is a good choice for areas with a lot of rain.

Insulate a Flat Roof

Insulating a flat roof averages $500 to $2,500, mostly depending on the roof size because larger roofs require more insulation. Installing insulation can be a good choice in areas with very low temperatures, trapping more heat inside and reducing the building’s reliance on electricity or gas-powered heating systems. It helps reduce utility bills in the long term and improve building efficiency.


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Labor Cost to Repair a Flat Roof

Contact professional roofing companies or experienced roofing contractors for roofing repairs. They have the experience and know-how to repair damage to your flat roof, with hourly rates ranging from $50 to $150 per hour. Some professionals may have call-out fees of $50 to $100, which may be waived if you hire them to carry out the necessary repairs. Some also charge extra if you live in an isolated area that requires a lot of travel to get to.

Emergency Flat Roof Repair

If you suddenly spot your roof sagging or have water coming down into the home through a hole or crack in the roof, it is vital to get emergency roof repairs as soon as possible. Many roofing companies charge extra for emergency same-day service. Expect to pay between $100 and $200 more than usual for this repair. Some companies have minimal emergency charges of around $150 to $200.

Flat Roof Maintenance

A good way to reduce the need for roof repairs and reduce the risk of having issues with your flat roof is to look after it correctly and carry out routine checks and maintenance tasks. Call in a professional roofing company once a year to carry out simple checks and inspections, at a rate of around $100 to $150. Or, you can inspect the roof yourself.

When inspecting the roof, look closely at key areas like the membranes, drain, drip edge, and flashing. Try to spot any cracks, holes, alligatoring, bubbling, blistering, or other signs of damage that might get worse later. Call professionals to have these issues repaired as soon as possible. The earlier you identify issues, the simpler the repairs will be.

It is especially important to check a flat roof after a storm or a snowfall. Storms can blow debris and branches onto the roof, which could cause damage. Snowfall may accumulate on the roof, so it might need to be removed if it does not melt or drain away quickly. Also, inspect the drain and check that water is flowing down, rather than pooling around the top.

Another tip for flat roof maintenance is to ensure the surrounding trees are regularly trimmed, removing any overhanging branches. Otherwise, those branches could fall onto the roof during a storm or strong winds, leading to impact damage like cracks and holes.

Repair vs Replacement

Flat roofs are not known to have very long lifespans. On average, many flat roofs last around 10 to 15 years, although some newer materials last considerably longer. If your roof is approaching 10 years and needs repairs, you may find that it is more cost-effective in the long term to replace the roof rather than to repair and then replace it within a few years.

If the roof needs extensive repairs or has damage to several areas, replacement may be your better option. A new flat roof costs around $7,500 on average. So if your roof is under 10 years old and has only one or two issues, your best option is to repair the roof to extend its lifespan and get the most use out of it.


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Enhancement and Improvement Costs

Flat Roof Inspection Cost

A professional inspection costs between $100 and $150. Inspect your roof at least once yearly to look for and address any issues you find. Flat roofs are generally easier to investigate and walk on than pitched roofs, making inspections easier.

Leaf Guard

A gutter guard system costs between $1,200 and $2,000 to cover all your gutters. Installing a leaf guard over your gutters and a roof drainage system helps prevent issues like debris clogs and ponding.

Waterproof Flat Roof

This process should be done by a professional and costs $150 to $1,000, depending on the roof size. Flat roofs are water-resistant because of the materials used. However, you can add an extra layer of waterproof protection with a rubber coating, additional membranes, or roofing resin.

Additional Considerations and Costs

  • Cracks. Always have small cracks and fissures in your roof sealed or repaired as soon as possible to prevent them from becoming bigger issues and leading to a total roof replacement. Have large cracks checked by a professional to make sure there are no bigger issues. Small cracks can often be sealed with a roof sealant if you catch them soon enough.
  • DIY. It may be possible to carry out small flat roof repairs on your own, such as clearing out a clogged drain or patching a small hole or crack with simple patching kits or sealant tubes. However, if you have any doubts or are dealing with serious roof damage, it is best to contact professionals.
  • Building code. Building codes vary from place to place and state to state. Some impose limits on the number of materials and membrane layers you have on a flat roof. Research the code rules in your area before having your roof resurfaced or replaced.
  • Warranty. Flat roof installations often come with warranties, ranging from 10 to 30 years. Know which warranty you have, how long it lasts, and what it covers.
  • License. Work with licensed professional roofers when repairing your roof because unlicensed workers could make mistakes and cause more harm. Always check the license of any professionals you hire.
  • Insurance. It can be harder than normal to get insurance for flat roofs. Some insurance companies do not accept flat roofs, while others accept them but charge a higher-than-average rate. Research and compare your options to find the best insurance policy for your flat-roof home.

FAQs

  • How much does it cost to repair a flat roof?

Repairs have a range of costs, depending on the issue. Most people pay $250 to $1,000 for repairs.

  • How do you waterproof a flat roof?​

Flat roofs can be sealed to make them more water-resistant. Roof sealants are spread or painted onto the roof.

  • Do all flat roofs leak?

A roof in good condition should not leak. Flat roofs have a shorter lifespan and are more likely to leak than other roofs, but this does not indicate a problem.

  • When should you replace a flat roof?​

If your roof has significant or widespread issues or if it is more than 10 years old, it may be time for a replacement.

  • How much does it cost to reseal a flat roof?​

Sealing a roof averages $150 to $1,000.

  • What is the average cost of re-roofing a flat roof?​

The average cost of a new flat roof is around $7,500 for a single-ply membrane roof.

  • What is the best way to fix a flat roof?

This depends on the damage. Holes and cracks can be patched or filled, while issues like alligatoring may require resurfacing.

  • What causes a flat roof to leak?

Leaks in flat roofs usually occur because there are cracks or holes in the membranes. These holes appear due to impacts, debris, storm damage, and general wear and tear.

  • Can you replace a flat roof yourself?

It is technically possible to replace a flat roof yourself, but this job is best handled by professionals.

Remodeling Terms Cheat Sheet

Definitions in laymen's terms, cost considerations, pictures and things you need to know.
See full cheat sheet.
glossary term picture Fiberglass 1 Fiberglass: Plastic that is reinforced with glass fibers. The fibers may be mixed randomly throughout the plastic, or come in the form of a flat sheet, or be woven into a fabric
glossary term picture Bitumen 2 Bitumen: A viscous, black mixture of hydrocarbons often used for roofing and waterproofing. It is also used in asphalt for paving roads
3 Fasteners: Hardware used to attach two or more objects to each other. A common example is a nail

Cost to repair a flat roof varies greatly by region (and even by zip code). To get free estimates from local contractors, please indicate yours.

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The information provided by our cost guides comes from a great variety of sources, including specialized publications and websites, cost studies, U.S. associations, reports from the U.S. government, contractors and subcontractors, material suppliers, material price services, and other vendor websites. For more information, read our Methodology and sources
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Cost to repair a flat roof varies greatly by region (and even by zip code). To get free estimates from local contractors, please indicate yours.

The information provided by our cost guides comes from a great variety of sources, including specialized publications and websites, cost studies, U.S. associations, reports from the U.S. government, contractors and subcontractors, material suppliers, material price services, and other vendor websites. For more information, read our Methodology and sources