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Should I seal my flat roof

We have sealed hundreds of roofs in Washington DC. Sealing a flat roof is tricky and understanding when to do it and over what is often misunderstood. The first thing to know is what type of flat roof do you have. There are typically only four different flat roofs found in the Washington Metropolitan area. These are Modified, TPO, EPDM and Built-up. Only one of these should ever be sealed and that is Modified. We run into situations where contractors actually seal an EPDM roof and if actually done can destroy any possibility of servicing it. The next thing to consider is why you should seal the roof. If you are experiencing a leak, sealing is not what you need. The leak simply needs to be found and repaired. Roof sealing is not a leak stopper, it is a way to prolong your aging flat roof. It will fill small voids in the membrane. A combination of properly repairing and sealing is many times an option, but make sure your roofing contractor knows what to look for when considering.

If you’re considering sealing your flat roof, you’ve come to the right place. Sealing your flat roof is a great way to ensure it looks great and is protected from the elements. This article will provide an in-depth look at everything you need to know about sealing your flat roof, including how to prepare for sealing, what types of sealants to use, how to apply the sealant, and how to maintain it. Additionally, we will explore the signs that indicate your roof needs to be resealed and how to find the right contractor to do the job. Lastly, we will answer frequently asked questions about sealing your flat roof.

Preparing your Roof for Sealing

Before sealing your flat roof, you must ensure it’s prepared for the process. This starts with thoroughly inspecting the roof and removing any old sealant that may have dried and cracked over time. You’ll also want to remove any surface debris, such as dirt or leaves. If you plan on applying the sealant yourself, you should also consider installing a substrate before applying any sealant to ensure that the sealant will stick properly.

The Types of Sealants Used for Flat Roofs

Generally, two types of sealants are used for flat roofs: asphaltic sealants and acrylic sealants. Asphaltic sealants are derived from a bituminous adhesive (usually tar or asphalt) and are generally used for low-slope roofs or roofs with a pitch of 12 degrees or less. These liquid sealants should be applied at least two times to ensure proper adhesion and sealing. Acrylic sealants, sometimes called rubberized sealants, are usually used on flat roofs as an alternative to asphaltic sealants. Acrylic sealants are waterproof, flexible, and adhere better to surfaces than asphaltic sealants.

How to Apply the Sealant to Your Roof

Once you’ve determined the type of sealant you’ll use, you’ll need to prepare the surface for the sealant by cleaning it thoroughly and using a premium-grade solvent-based primer. After the surface is prepped, you’ll want to apply the sealant in a thick layer using a brush, roller, or spray. Remember that sealants should be applied in two thin coats, allowing each coat to dry before applying the second one. After applying the sealant, you’ll need to protect it from the elements by using roof edge and domed caps to prevent water runoff.

Maintaining Sealed Flat Roofs

Maintaining a sealed flat roof is relatively simple if you regularly inspect it for problems. Once a year, you’ll want to inspect the sealant for signs of cracking, discoloration, or any other warning signs that the sealant may need to be resealed. Also, you’ll want to ensure that any roof edge and domed caps previously installed are still in good condition and waterproof. Additionally, you should clean the roof every few months and examine it for any damage, including broken shingles, missing tiles, and other signs of age and wear.

Signs that Your Flat Roof Needs Resealing

While inspecting the roof is one way to tell if it needs to be sealed again, certain signs indicate that the sealant should be resealed, such as cracks in the sealant caused by changes in temperature, UV damage, or water damage. You may also notice that the sealant has become brittle and is no longer flexible. Patching the roof every few years can also be a sign that it needs to be resealed, as the patches may not prevent water from penetrating the roof if the sealant is in poor condition.

Choosing a Contractor to Seal Your Roof

Hiring a professional to seal your roof is always recommended, as they have the expertise to inspect and seal it properly. When hiring a contractor to seal your flat roof, ensure they have experience with sealants and are familiar with your type of roof. Also, ask if they have any references or reviews, and ensure they are licensed and insured.

FAQs About Seal My Flat Roof
  1. How often should my flat roof be sealed?

– Generally, it’s recommended to reseal your flat roof every 3-4 years. However, the exact timeframe may vary based on the climate and conditions of your roof.

  1. Is it hard to maintain a flat roof?

– Not at all! If you inspect and clean your roof regularly, you should have no problem keeping it in great shape.

  1. Is it more cost-effective to hire a contractor to seal my roof or do it myself?

– Generally, hiring a contractor to seal your flat roof is more cost-effective, as they will be aware of the necessary materials, tools, and safety measures to do the job properly.


Sealing your flat roof is essential to keep it looking great and prevent water and other elements from damaging it. Preparing the roof for sealing, choosing the right type of sealant, and applying the sealant properly are all important steps that can help you ensure your roof is properly sealed. Additionally, it’s important to inspect the roof regularly for signs of damage or wear and to hire a contractor if necessary. Following these steps, you can help ensure your flat roof is properly sealed and in great condition.