A Guide To Modified Bitumen Roofs – Can They Be Repaired?

Modified Bitumen Repair2 Lg

If you want to protect a near-flat or flat roof, then modified bitumen coating is among the most popular options you should consider. Apart from adding benefits like flame resistance, the solution also offers superior resistance against damage to the roof and elements. 

However, no coating solution is ideal, and the possibility of bitumen coating getting punctured or cracked is always there. 

The good news is that when modified bitumen coating gets damaged, it’s possible to repair it. There are several ways that you can do this, although patch application is the most common approach.

In this article, we are going to look at how bitumen coating works. 

Repairing Your Rooftop Using Modified Bitumen Coating

There are several steps that you must follow while repairing your roof using modified bitumen coating, as we’ll explore below:

Analyze and determine the amount of damage

The biggest issue about repairing modified bitumen roofing is whether the moisture has found its way into the asphalt layer and, if it has, to what extent. Therefore, you must do a thorough inspection of the modified bitumen roof. 

If there is damage, you should replace any lower-level deck material or affected insulation before patching the top.

Cleaning of the membrane

Patching is something that requires a clean surface. It’s therefore important that you thoroughly sweep the outer membrane to remove any debris or dirt. 

It would be best never to power wash the surface to prevent moisture from being trapped inside the membrane. 

Deal with weathering

Depending on the age of the coating and the amount of damage, the asphalt layer may become extremely disturbed and thus need a thick coating to fill gaps in the membrane

Patching of the roof membrane

Before you initiate any project, you should ensure that the roof is completely dry. In addition, the roof should not have any moisture or morning dew. 

The patching process is relatively straightforward. Liquid rubber coatings that are purchased from manufacturers are used. 

For instance, you can use a mastic coating such as TRUCO’s 7174 Elastomeric Flashing cement and reinforce it with a polyester membrane. It would be best if you left several inches on all sides for total overlap without leaving gaps. 

After the fabric is completely embedded into the mastic, you should use a dry and clean paintbrush for back sweeping the polyester membrane so that no blisters, air pockets, or wrinkles are visible. Then apply a layer of top coatings to seal the fabric and prevent moisture from penetrating.

Extend the Lifespan of the modified Bitumen Coating

There is no argument that bitumen is an excellent and effective material for covering a roof. However, you can make the coating more durable by adding rubberized coatings. 

Rubberized coating adds more resistance to the coating and prohibits debris from affecting any bitumen underneath. Repairing the coating also becomes easier. 

Signs that Shows that Modified Bitumen Roofing Needs Repair

Modified bitumen is an asphalt material reinforced using butadiene and polypropylene or styrene that can be cold-applied or heat-applied respectively on a flat roof surface. It provides various benefits compared to other flat roofing materials. 

The advantages of the coating include:

  • It is very durable
  • Has a resistance to damage as a result of different weather conditions
  • Modified bitumen is easy to repair and install

Despite having all these advantages, it’s unfortunate that modified bitumen roofing will require periodic repairs and replacements. Just like other coatings, modified bitumen repairs can result in extensive repair costs. 

In most cases, roof damage starts slowly and may go unnoticed after a significant amount of damage. However, the impact from such an occurrence may pose severe challenges to managers and owners of the properties involved. 

In addition, the tenants and their visitors can also be affected in the process. 

Therefore, it is important for the managers or owners of properties that have modified bitumen roofing to conduct routine roof inspections. In addition, you should ensure that the materials keep on offering the level of performance and service expected and needed. 

During inspections, it’s possible to identify potential threats that you could address immediately to avert emergency repair bills. 

The signs that show that your modified bitumen roofing requires repair include: 

  • Delamination: This is a situation where individual layers slip or separate, thus losing durability.
  • Worn asphalt: It involves areas or spots of surface erosion exposing underlying layers.
  • Punctures, Cracks, and Tears: Involves outward damage resulting from falling debris, weather among other causes. 
  • Raised or loose fasteners: This might result from the expansion of the materials or natural contractions. 
  • Return of prior issues: It results from original repairs that have not been held or not done correctly.
  •  Pooling: Dirt/debris/water collecting in depressions and the process stressing the roof’s structure.
  • Grease involves the deterioration of a single or multiple layers near the venting, especially on restaurant roofs.
  • Improper initial installation: it isn’t readily evident; as a result of sub-par materials or work.

Although some of these signs might be more easily noticed than others, especially to untrained people, they all present sources of roof leaks. It’s therefore critical that repair is done before the building envelope, interior contents, and roofing structure are exposed to more expensive loss or damage. 

Preventative Roof Maintenance to Avoid Costly Repairs

Although the maintenance staff or property owner can carry out regular inspections, it’s crucial to incorporate the services of professional roofing contractors. The use of such services will eliminate any injury risks for untrained or inexperienced individuals, especially those who aren’t comfortable with heights. 

It also enables specialists to evaluate and assess the whole roofing system for different concerns. In addition, many companies have comprehensive preventative maintenance programs designed to evaluate the condition of any roof on a semi-annual basis. 

If a roof repair is needed, such companies can repair work after receiving approval from the property owner. A comprehensive preventative program has a complimentary report on visual inspections and reviews such as:

  • A roof profile
  • An overall evaluation of the current condition of the roof
  • Photos of the roof before and after repairs


If you have a nearly flat or flat roof, you can protect it using modified bitumen coating. However, for effective performance, you must do regular repairs on the coating. If you need assistance to do anything, always contact a professional.


Hubert Miles | Licensed Home Inspector, CMI, CPI

Hubert Miles is a licensed home inspector (RBI# 2556) with more than two decades of experience in inspection and construction. Since 2008, he has been serving South Carolina through his company, Patriot Home Inspections LLC. As a Certified Master Inspector, Hubert is dedicated to providing his expertise in home inspections, repairs, maintenance, and DIY projects.