Flat Roof Repair

Flat roof repair, which is also called “low slope roof repair,” or commercial flat roof repair can be anything from a simple fix to a reconstruction that requires a complex roof insurance claim and the help of an experienced professional.

flat roof repair

Step by Step Flat Roof Repair Method

If your roof cannot be saved, you must choose a local roofer to replace it. We’re going to take a look at how you can conduct a flat roof repair yourself in this post. This tutorial is for you if you have a leaking roof. Come on, let’s get this party started!

Clean your Roof

The first and most critical step in any repair is to make sure your gutters are clear of material that might obstruct water flow. Because flat roofs do not drain as well as pitched roofs, it is critical to ensure that the drainage system is sufficient before installing a flat roof.

To dry puddles of water, use towels or rags. The next step is to allow it to dry. In addition, take care to clear any debris so that you can readily identify the cause of leaks. When you find leaks, mark them with chalk and return to patch them later.

Repair the Roof Seams

EPDM roofing seams might degrade over time if you don’t inspect them carefully. It’s common for water and sand to pile up. As soon as you’ve thoroughly cleaned your seams, you may begin applying glue to the one that is leaking.

Spread the glue over the top and lower seams, as well as the corners, using a soft brush (such as a paintbrush). Be careful to push the seams together after applying the glue. There must be no air bubbles in the mixture. The seams won’t stick together if you fix them on a windy day, so don’t do it!

Repair Blisters on a Flat Roof

A flat roof’s blistering is a regular occurrence. Roof blisters allow air or moisture to gather under the membrane of a flat roof. These imprisoned bubbles expand and shatter when they are exposed to the sun’s heat. You should keep in mind that even if a blister does not rupture, it may still create issues.

Using a utility knife, cut the blister open in the center to stop it from expanding. It should be able to drill the blister all the way through. If the blister is wet, gently press out the excess liquid and allow it to air dry. Apply a thick layer of roofing cement to the blister to permanently seal it off.

Repair your Flat Roof’s Coating

It is time to recoat your roof after removing dirt and blisters from the surface. Recoating is a viable alternative since it protects your roof from water damage, keeps your interior cooler by reflecting solar heat, and lowers your energy bills.

Adding a new rolled roof over an old one is an option if you like a flat roof with rolled roofing. Rolled roofing should be completely flat throughout. The installation procedure will be simpler if you trim the rolls before attaching or adding an adhesive to them.


Older houses especially those located in dry climates tend to have flat roofs, which are generally flat. These roofs perform well, but you should check for deterioration and cracks from time to time. Asphalt, rubber, PVC, or another synthetic substance is the most used material for flat roofs. Adhesive repairs make quick work of rubber and synthetic membranes, while caulk or bitumen may restore seal to asphalt. If your roof isn’t in terrible condition, it’s best to have it fixed as soon as possible to avoid serious damage and extend the life of your roof.

What Is the Reason for Flat Roof Leaks?

Flat roof leaks may be caused by a variety of factors. The following are typical citations:

  • Drainage is not up to snuff. Water will pool if your roof is unable to adequately drain it. Standing water may deteriorate the roof’s roofing materials over time, increasing the risk of a leak.

  • An antique tin roof. Older roofs are more susceptible to leaks since the roofing material has been exposed to heat, sun, rain, and wind for many years.

  • Flashing is broken. The corners of the roof are exposed to the elements, especially rain if the flashing is improperly placed or destroyed. Water might get into the roofing system if the flashing isn’t properly installed.

  • The roof has a leaky membrane. The inside of the roof is subject to water damage and leaks because of the roof membrane’s tearing, cracking, puncturing, shrinking, and scorching.

  • A puddle of water. If you have a flat roof, even a tiny amount of standing water may put a lot of stress and wear and tear on it. Leaks are inevitable because of these reasons, which eventually undermine the roof.

  • Ventilation holes in the roof. Vents, pipes, drains, and HVAC units must be inserted into the roof membrane. These perforations are no longer waterproof over time. The membrane and the roofing system are vulnerable to water probing, which may lead to leaks.

How to Temporarily Fix Flat Roof?

This implies that you’ll have to do part of the work yourself until you can afford to hire a contractor to fix your roof.

Look for a Leak

Locate the leak’s origin inside the structure. The leak may not be the area with the most water since the water may have flowed through the leak and accumulated in a different area of your roof. To check for leaks, take a few measurements of the region and compare them to the surrounding walls.

Climb to the Rooftops

Begin searching for the leak on the roof using the measurements you’ve taken from the inside. Flashing and vents on the roof may be a good place to search for roof membrane problems. For safety reasons, you should only use a ladder if you have to go to the top of your building. If your roof is too high or you are concerned about your safety, or if you simply cannot locate the source of the leak, you should contact a professional.

Take Care of All Debris

Debris on your roof might hamper your work or worsen the harm already done. Before beginning any work on the roof leak, make sure to remove any foreign items from the area. As a result of the inspection, you’ll know whether or not your roof has been damaged by a storm or whether it is just aging.

Drench the Place

When working on a flat roof, it’s important to make sure the surface is completely dry before beginning any repairs. Mold may form beneath your roof if you fix a hole and seal it with a patch that traps water below. If water is already leaking through your roof’s layers, you may need the services of a professional.

Recognize the Damage

This may suggest that water or air has gotten in between the various layers of your roof, which can lead to blisters. Cracks or alligatoring, which is often a sign of long-term UV damage, should also be looked for. The best way to fix your damage depends on the sort of damage you have. It’s recommended to contact a specialist in the event of significant damage.

Cut off the Damaged Area

Remove any water that may be trapped in the injured membrane by cutting it open with a utility knife. Cutting away the damaged layers of your roof membrane is necessary, but be cautious not to harm the roofing felt underneath. Dry the places you want to repair completely before continuing to step two of the process.

Put Roofing Cement on the Roof

The membrane layers you removed may be peeled back and roofing cement can be applied to both the leak and the full length of the roof underneath the membrane layers you removed. This will seal the hole and serve as an adhesive for the membrane’s movement. To reseal the wound, press the membrane movement against the cement.

Make a Point of It

Nail the blister movement to the roof once you’ve laid them down to ensure that they’re secure and that the leak is sealed. Be careful not to damage any cables or other critical infrastructure during nailing. Using extra roofing cement, fill any holes you may have made around the nails with.


On both commercial and residential properties, flat roofs may be found. Flat roofs tend to develop problems fast, necessitating repairs every few years, due to the lack of pitch or slope. If your flat roof leaks, you may need to repair it to fix the problem. Even with regular maintenance, flat roofs are susceptible to alligatoring, blistering, bubbling, and drooping. These problems may be repaired in a variety of ways, but the prices and techniques vary.

Flat Roof Repair Cost

Repairing a leaking flat roof typically costs between $250 and $1,000 for a professional, with the majority of homeowners shelling out about $600 on average. The cost of this job is around $50 to restore a few shingles that have been damaged. To prepare for a new flat roof, this job will cost $5,000 to remove the old one.

Flat Roof Repair Cost
National Average Cost $600
Average Range $250-$1000
Minimum Cost $50
Maximum Cost $5000

How Do Stop Flat Roofs from Leaking?

It’s terrible to find out that your roof is actively leaking. It’s always better to be proactive about roof inspections and maintenance so that water doesn’t pool up too much, holes don’t form, and bigger problems don’t happen. Here are some easy ways to avoid it:

  • Keep your flat roof clean at all times. Flat roofs tend to get a lot of different kinds of trash on them. Make sure to clean up this trash, such as branches or leaves that have fallen. This will help keep from getting a hole. Even better, keep your trees in good shape. Cut back tree branches that hang too low.

  • Keep your gutters or drains clean. As we’ve already said, a common problem with flat roofs is that they can’t drain off completely. To make sure your drains work well, clean out the plants, dirt, and other things that grow around their openings.

  • Do a quick inspection. If you don’t have much time, you should be able to find signs of problems with your flat roof, such as blistering, ponding water, cracks, leaks, and more.

Frequently Asked Questions

Here are some FAQs related to flat roof repair:

1. Are flat roofs repairable?

EPDM roof leaks and cracks may be fixed permanently with a simple patch. Tape 3" of self-adhesive rubber tape over the hole and apply EPDM primer when it is touch-dry. A strong, hard roller should be used to apply the patch from the center (over the hole) outwards.

2. How can a large hole in a flat roof be repaired?

As much as possible, spread the cement beneath the roof covering. It’s best if you can extend it by at least 2 inches (5.10 cm). When applying patches, do not use caulk. To use caulk as an adhesive is a waste of time and money.

3. Is it possible to fix a rubber roof?

One-half of the defined repair area and half of the patch’s underside should be coated with rubber-to-rubber contact cement by using a 3-inches paint roller to apply the adhesive. The cement should dry in approximately 10 minutes. Set the rubber patch in place, matching it with the shape drawn on the roof earlier, and then press it firmly in place.

4. Do you know the meaning of flashing?

To prevent water from entering your home via gaps in your roof, you need flashing. This may be metal or rubber. Openings or holes in the roof surface, such as chimneys, flues, skylights, and vents, are present on every roof.

5. Does a roof need to be refelted?

There will be no 100% water tile in any repairs made from the inside. There is no use in performing half a job, just to have to do it again, therefore repairing the felt from the inside would be extremely cowboy-ish. After some time.

6. To put it another way: What exactly is EPDM rubber roofing?

Synthetic rubber EPDM, or ethylene propylene diene monomer (M-class), is exceptionally durable and widely utilized in a range of industries. EPDM’s two basic constituents, natural gas, and oil are heat and weather resistant, making it perfect for flat roofing.

7. What’s the best way to fix a rolled roof?

Remove and discard the old rolled roofing. Make sure that the new roll is slipped beneath the previous rolled roofing before putting it on top of it. With a wooden stick, spread tar or cement beneath the fresh roll of rolled roofing. Roll out the new roofing, and then finish the job.

8. When it comes to drainage, how do you slope a flat roof?

At least a two percent slope or one-fourth unit vertical for every 12 horizontal units is required by contemporary construction rules for drainage considerations One-quarter of an inch for every 12 inches is required for the roof to the slope. To the open eye, the slope is scarcely discernible.

9. To fix a leaky roof, what can I use?

Rubber In the field of roof mending and repair, Flexx Sealant is a game-changer. This long-lasting rubberized patch is developed to probe deep into damaged areas and stop roof leaks right away!

10. Does Flex Seal have any effect on the surface of roofs?

Managing roof leakage may be made simple using Flex seal for roofs. When the roof is leaking or has a leaky condition, the sealant may be applied. Flex seal is available in a liquid form for ease of use and excellent performance. When installed, it shields your roof from the damaging effects of corrosion, ultraviolet light, and mildew development.


Do-it-yourself flat roof repairs can help you deal with roof problems as best you can. No matter how well you take care of your roof, though, there will come a time when it will no longer work. If your roof is 20 years old, it’s time to call roofing contractors in Brantford to take care of it.

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