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Flat Roof Repair Cost

Flat Roof Repair Cost

National average
$500
(patching and sealing up a mild to moderate crack in the roof)
Low: $200

(unblocking a drain filled with debris to make it easier for water to drain)

High: $800

(restretching and anchoring the roof and sealing the edges)

Cost to repair a flat roof varies greatly by region (and even by zip code).
Get free estimates from roofers in your city.

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Flat Roof Repair Cost

National average
$500
(patching and sealing up a mild to moderate crack in the roof)
Low: $200

(unblocking a drain filled with debris to make it easier for water to drain)

High: $800

(restretching and anchoring the roof and sealing the edges)

Cost to repair a flat roof varies greatly by region (and even by zip code).
Get free estimates from roofers in your city.

The average cost of repairing a flat roof is $200 - $700.

How Much Does It Cost to Repair a Flat Roof?

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. The average cost range for this project in the U.S. is between $200 and $700, and most homeowners find that the cost to patch a leak on a modified bitumen or single-ply membrane roof is around $500.

Flat Roof Repair Costs

Flat roof repair costs
National average cost$500
Average range$200 - $700

Minimum cost

$200
Maximum cost$800


Signs Your Flat Roof Needs Repair

The first sign that your flat roof needs repair is usually water leaking inside your home. However, other more subtle signs often precede this. These include water stains on the underside of your roof deck, mold or mildew in your attic, and visible cracks, bowing, or creasing of your roof material. You may also see small puddles of water on your roof, which can indicate a problem, or you may notice the flashing 1 around things like chimneys and vents may be damaged or missing.

Cost Factors

Several factors influence what you will pay for the repair of your flat roof. The first is the roofing material. Flat roofs may be made of a single-ply membrane, which can be PVC, rubber, or other synthetics, covered in modified bitumen 2, or be a built-up roof (BUR). Each of these roofs has different repair strategies, which influence the cost.

In addition, the problem that your roof has can also affect the cost. For example, a small crack or rip in the roofing needs a different solution and cost than the roofing material coming loose on the edges and needing to be tacked back down.

Finally, the scope of the problem can impact the price, such as how big or small the issue is and where on your roof it is located. For example, a small crack near the edge will be easier to repair than a large hole near the center.

Common Problems

Flat roofs are often subject to several common issues that can all result in rain or moisture infiltrating your home:

Ponding

Ponding is an occurrence that creates small puddles or pools of water on your roof. It usually occurs when water cannot drain properly off the roof and can lead to more serious issues, such as cracks or deterioration of the roof. The solution is usually to find the blockage in the drain system and clean it out. This can cost $200 but may increase, depending on how bad the blockage is.

Debris

Flat roofs often collect things like leaves, pine needles, and other debris. Over time, they can clog your roof drain system, causing it to dam. This can lead to leaks, deterioration of your roof, and ponding. The solution is to clear away the debris and, if necessary, unclog the drain system. This can cost around $300 but varies depending on the size of your roof, how much debris, and how bad the blockage is.

Alligatoring

When your roofing material begins to age, it may crease and crack and take on the appearance of alligator skin. This can lead to small rips and tears in the roof material, which can then lead to water leaks. The solution can be to patch the area with a new piece of membrane or material, but sometimes you can cover the affected area with a sealant. Costs are usually around $500, depending on the size of the repair.

Buckling

As your house settles, your roof may buckle in places. This can appear as shallow dips, or it may cause the membrane to push up in areas. This can lead to a shortening of the lifespan of the roof, as well as eventual leaks. Depending on the type of roof, you may be able to fix it by stretching the material and anchoring it, or it may need to be patched or sealed. Costs range from $200 - $1,000 depending on the level of work.

Wind

Wind causes a lot of damage to all roofs by loosening the material and allowing rain to get beneath it. Flat roofs that are loose on the edges can peel, crack, and allow a lot of water under the roofing material if wind has damaged the roof. Sealing or patching the affected areas will usually solve the problem. Costs are roughly $800 in most instances.

Leaks

Leaks are usually the biggest cause for concern from homeowners. They can be caused by many of the above issues or by cracking or ripping of the roof material. Patching and sealing the roof are the two most common methods of fixing a leak, and costs are around $500 for most leak repairs but can go higher for extensive problems.

Flashing

The flashing that seals the edge of your roof, as well as any penetrations like skylights or chimneys, can also crack, rust, or be missing. If this is the problem, it can lead to leaks around these areas. New flashing can be installed for $200 - $500 in most instances.

Repair vs Replacement

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

Likewise, if the roof needs extensive repairs or has damage to several areas, then 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, then your best option is to repair the roof to extend its lifespan and get the most amount of use out of it.

Enhancement and Improvement Costs

Leaf Guard

Installing a leaf guard over your gutters and roof drainage systems helps prevent issues like debris clogs and ponding. A gutter guard system costs around $1,900 to cover the entirety of your gutters.

Roof Sealant

Most flat roofs need to be sealed to prevent issues with standing water. Your roof will likely be sealed at the time of install but can be resealed as necessary. Costs for sealing your roof are usually around $200 on average.

Additional Considerations and Costs

  • 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, which can make inspections easier.
  • 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 the need for a total roof replacement. Have large cracks checked by a professional to make sure that there are not bigger issues at play. Small cracks can often be sealed with a roof sealant if you catch them soon enough.

FAQs

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

Repairs can have a range of costs depending on the issue. Most people pay around $500 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 indicate a problem. 

  • When should you replace a flat roof?

If your roof has significant or widespread issues or if it is more than 15 years old, it may be time for a replacement.

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

Sealing a roof costs around $200 on average. 

  • 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.

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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 Flashing 1 Flashing: Pieces of sheet metal used on roofs to cover joints, such as where the roof meets the wall, or around a chimney or skylight, to protect them and prevent water leaking through
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

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.

Flat Roof

Labor cost by city and zip code

Compared to national average
Anchorage, AK
+35%
Ashland, NH
+22%
Athens, GA
-9%
Austin, TX
+13%
Baltimore, MD
+12%
Boston, MA
+40%
Buffalo, NY
-1%
Cedar Rapids, IA
+6%
Chicago, IL
+40%
Cleveland, OH
+7%
Coldwater, MI
-21%
Corpus Christi, TX
+4%
Dallas, TX
+10%
Detroit, MI
+16%
Dunedin, FL
-14%
Fort Worth, TX
+6%
Fremont, CA
+35%
Hartford, CT
+23%
Hollywood, FL
0%
Houston, TX
+24%
Huntsville, AL
-17%
Indianapolis, IN
+6%
Jacksonville, FL
-1%
Laurel, MT
-12%
Los Angeles, CA
+11%
Memphis, TN
+11%
Miami, FL
+1%
Orlando, FL
+2%
Pelkie, MI
-28%
Pensacola, FL
-19%
Philadelphia, PA
+40%
Phoenix, AZ
0%
Pittsburgh, PA
+9%
Reno, NV
0%
Sacramento, CA
+8%
Saint Louis, MO
+16%
San Diego, CA
+11%
San Francisco, CA
+53%
San Jose, CA
+33%
Seattle, WA
+9%
Smyrna, GA
+10%
Tampa, FL
-2%
Tucson, AZ
-19%
Washington, DC
+23%
Wichita, KS
-13%
Wilmington, DE
+9%
Winston Salem, NC
-1%
Labor cost in your zip code
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Methodology and sources