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How To Fix a Flat Roof Leak: How to Repair, Patch, Tips, and More!

how to fix a flat roof leak puddle

A leaking roof is no one’s idea of a good day. Whether it is a slowly growing water stain in the ceiling, or an active drip every few seconds, any leak can cause expensive water damage if ignored. That’s why it’s best to learn how to fix a flat roof leak so you can stop any damage fast!

But how do you fix a flat roof leak? There’s a lot to cover, but we’ve done the research for you, so when you find a leak, you can jump into action. Read on to learn all about how to fix a flat roof leak.

When Should I Repair a Flat Roof?

Obviously, if your roof is leaking, it is in need of some TLC. But there are other signs to watch out for that can indicate that it is time for a flat roof repair.

  • Mold and Moss Growth – If you are noticing mold, moss, or algae beginning to grow on your roof, it’s a sure sign that moisture is not properly evaporating.
  • Water Pooling – While some water pooling after a rainstorm is normal, water pooling on your roof for an extended amount of time could be a sign that the structure of your roof is failing.
  • Water Stains – If you see water stains on your ceilings and walls, it’s a good idea to call in a professional to assess whether or not the leak is coming from your roof
  • Blistering – Blistering or bubbling on your roof’s surface means that your roof may no longer be adhering properly.

tear in flat roof material

Why is My Flat Roof Leaking?

There are all sorts of reasons your flat roof may be leaking. All roofs eventually face some wear and tear from continued exposure to the weather. Hot, sunny weather causes roofing material to expand or dry out, while colder weather can make it contract. This can lead to cracks and warping, making a flat roof repair necessary.

If your area has recently experienced natural disasters, such as a tornado, hurricane, or hailstorm, your roof is vulnerable to extensive damage. Be sure to check it as soon as possible.

The truth, though, is that sometimes roofs just fail because of age. Most flat roofs will last an average of 10-20 years. As your roof ages, it is more prone to damage that can cause leaks. If your roof is within that age range, it may simply be time for a roof replacement.

How to Find the Leaking Area

If your commercial building has a flat roof, you are in luck! Leaks and damage are much easier to spot on a flat roof vs. a sloped roof. The easiest solution is to look directly above the spot where the indoor leak is occurring. If you cannot see any visible signs of damage, be sure to check the areas of your roof that could cause water to run off into this area. Despite the name, most flat roofs have a slight slope in order to allow water to run off.

Types of Flat Roof Materials

The type of flat roof repair you need will be highly dependent on its roofing systems and material. Here are some of the most common types of flat roof materials on the market.

how to fix a flat roof leak patching roof

Modified Bitumen

Modified bitumen is made of asphalt and fiberglass and installed in a multi-ply system.

Built-Up Roofing

A built-up roof has several layers of roofing material that are melded together with hot tile and then topped with stone.

EPDM Roofing

EPDM roofing consists of durable rubber that can be attached in a variety of different ways. This is typically one of the easiest types of roofing materials to install.

TPO Roofing

TPO consists of a single-ply roof membrane that is made out of rubber.

PVC Roofing

PVC is a single-ply roofing system that is known for being lightweight and increasingly popular amongst roofing contractors.

Gathering Materials for Flat Roof Leak Repair

To fix a flat roof leak, you’ll need a few essential materials. Roofing cement is a go-to for many repairs, as it creates a durable, waterproof seal. Additionally, have a putty knife or trowel on hand for applying the cement. If the leak is near a vent or pipe, you might need flashing material to ensure a secure seal around these areas. For larger tears or holes, consider having a patch of compatible roofing material ready.

How to Fix A Flat Roof Leak: DIY

  1. Safety First: Before climbing onto the roof, ensure safety measures are in place. Use a sturdy ladder and have someone else aware of your task.
  2. Clear Debris: Remove any debris from the area around the leak. This ensures a clean surface for the repair and helps prevent further damage.
  3. Locate the Leak Source: Sometimes, water can travel along the roof before dripping down, so the exact source may be a bit away from where you see the water inside. Trace the water stains back to their origin on the roof.
  4. Apply Roofing Cement: Using a putty knife or trowel, apply roofing cement generously to the area around the leak. Extend the application a few inches beyond the damaged area to ensure a watertight seal.
  5. Secure Flashing (if needed): If the leak is near a vent or pipe, cut a piece of flashing to fit around the base. Apply roofing cement underneath and on top of the flashing to secure it in place.
  6. Patch Larger Holes: For larger tears or holes, cut a patch from your spare roofing material. Apply roofing cement around the edges of the patch and press it firmly onto the damaged area.
  7. Inspect the Repair: Once the cement has dried, inspect the repair to ensure there are no gaps or loose edges. This is crucial for long-lasting effectiveness.

How to Fix Flat Roof Leaks: Professional

When it comes to flat roof repair options, a professional roofing company is your best bet to ensure the problem does not happen again. Most roofs come with a warranty, and you may be able to get the necessary repairs without much cost to you.

A professional roofer will perform a roof inspection and advise you as to the next steps. If you do not need a full roof repair, they may suggest that you consider a roof coating.

A roof coating will help seal your roof to prevent further damage.

roofing contractors showing how to repair a flat roof leak

How Much Will It Cost to Fix a Leaking Flat Roof?

The cost of repairing a flat roof will vary greatly, depending on the state of your roof. A full flat roof replacement will cost between $5000-$15,000, depending on the size.

If only a roof repair is needed, then you can expect to pay $300-$1000.

When to Call a Roofing Contractor

While DIY flat roof leak repair can be effective, there are instances where professional help is necessary. If the damage is extensive, or if you’re uncomfortable working on the roof, calling a roofing contractor is the safest bet. They have the expertise and tools to assess the situation thoroughly and provide a lasting solution to your flat roof leak problems.

At Anchorpoint Roofing, we take the stress out of caring for your roof. Our team of highly skilled professionals is here for you to ensure that your residential and commercial roofs are cared for. Contact us today for a free quote!

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