top of page

Hot Mop Built-Up Systems

What Is Hot Mop Built-Up Systems?

Hot Mop Built-Up Systems have been around for many years and some consider to be the most effective way of covering a flat or low-slope roof.  Hot Mop Built-Up Roofing Systems are comprised of multi-layers of asphalt and roofing felt.  The plies, or different layers of asphalt and felt are interwoven to provide a multi-layered waterproofing system for your flat roof.  Hot Mop Built-Up Systems can be topped with gravel or an asphalt capsheet depending upon the needs of the individual roof and climate zone.

Hot Mop Systems are extremely durable and can easily last 15 years or greater without the need for a full roof tear-off.  They can also be installed quickly and tend to be affordable compared to other roofing systems.

Preparation and Installation of Hot Mop Built-Up Coatings

The hot mop process allows for the creation of multiple layers, providing added strength and waterproofing capabilities to the roof. The layers of asphalt and felt work together to form a continuous and seamless membrane, preventing water from penetrating the roof structure.

Below is a step-by-step explanation of how hot-mop built-up commercial roofing systems are installed:

Surface Preparation: The existing roof surface is cleaned and prepared by removing any debris, loose material, or damaged sections. The roof deck is inspected for any structural issues and repaired if necessary.

Insulation: If insulation is required, it is installed on the roof deck to provide thermal resistance and energy efficiency. Insulation boards are commonly used and are placed over the deck in a staggered pattern.

Base Layer: A base layer, also known as a base sheet or ply, is applied to the roof deck. The base layer is typically made of fiberglass or organic felt material. It is rolled out and nailed or fastened to the roof deck using mechanical fasteners.

SRS Roofing Website Images (2).png

Hot Mopping: The hot mopping process involves heating asphalt or tar to a liquid state. This heated material is then poured or mopped onto the base layer. Roofing contractors use large mops or brooms to spread the hot asphalt evenly across the surface, saturating the base layer.

Reinforcing Layers: After the hot asphalt is applied, additional layers of felt or fiberglass material are placed on top of the hot asphalt. These layers are embedded into the asphalt while it is still hot, creating a strong and durable roofing membrane.

Surfacing: Once the reinforcing layers are in place, a surfacing material may be added to the top of the roofing system. This can include gravel, mineral granules, or a reflective coating. The surfacing material provides protection against UV rays, improves aesthetics, and prolongs the lifespan of the roof.

Advantages and Disadvantages of Hot Mop Built-Up Systems

It's essential to consider these advantages and disadvantages in the context of your specific roofing needs, local climate, and building requirements before deciding on a hot mop roofing system. 

Advantages of Hot Mop Systems:

Cost-effective: Hot mop roofing systems are relatively cost-effective compared to other roofing options, such as single-ply membranes or metal roofs. The materials used in hot mop roofing, including asphalt and gravel, are generally less expensive than other roofing materials.

Durability: Hot mop roofs are known for their durability. They have a multi-layered construction that can withstand heavy foot traffic and provides excellent protection against extreme weather conditions, including UV radiation, rain, and hail. The multiple layers of asphalt and gravel create a strong, resilient barrier.

Heat resistance: Hot mop roofs have superior heat resistance properties, making them suitable for regions with high temperatures. The layers of asphalt and gravel act as a heat barrier, keeping the interior of the building cooler.

Repairability: In case of damage, hot mop roofs are relatively easy to repair. Localized repairs can be done by reapplying hot asphalt and gravel to the affected area, which extends the lifespan of the roof.

Longevity: Hot mop roofing systems have a long life span, typically lasting 20 to 30 years or more with proper maintenance.

Disadvantages of Hot Mop Systems:


Installation complexity: Hot mop roofing systems require skilled and experienced contractors for proper installation. The process involves heating asphalt to a high temperature and then mopping it onto the roof surface. The complexity of the installation process increases the risk of errors if not done correctly.

Heavyweight: Hot mop roofs are relatively heavy due to the multiple layers of asphalt and gravel. This weight can put additional stress on the building structure, particularly in older buildings that may not have been designed to support such loads. Structural reinforcement may be required before installing a hot mop roof.

Odor and fumes: The installation process of hot mop roofing involves heating asphalt, which can produce unpleasant odors and fumes and often require precautions to protect workers and occupants.

Limited design options: Hot mop roofing systems have limited design options compared to some other roofing materials. The traditional gravel appearance may not be suitable for all architectural styles, and customization options are relatively limited.

Maintenance requirements: Hot mop roofs require regular maintenance to ensure their longevity. Periodic inspections and reapplication of asphalt and gravel are necessary to address any wear, tear, or damage that may occur over time.

Unmatched Roofing Experience and Services Across Southern California

Don't settle for anything less than excellence when it comes to your roof. With 20+ years of experience, we guarantee quality workmanship and customer satisfaction. Whether you're dealing with a leaky roof, seeking a complete replacement, or simply need routine maintenance, we've got you covered. Our team of experts provides professional and comprehensive roofing services to ensure your roof is in the best condition.

Contact us today for quality craftsmanship and reliable service.

Experience Is On Your Side

You can count on Superior Roofing for all your commercial and residential roofing-related needs. Whether you are a homeowner, property manager, or building owner, Superior Roofing Systems offers unmatched customer service and experience to guide you through the roofing process. Our services include assessing roof damage after storms, performing complimentary inspections, repairing leaks, and performing preventative maintenance. Superior Roofing Systems works with government agencies, subcontractors, HOAs, property managers, & large complexes.​

Schedule a Complimentary Roof Inspection

Conveniently located in Anaheim, the heart of Orange County, our team of experienced roofing professionals provides roofing services to residential and commercial properties throughout Southern California. This includes Orange County, Riverside County, San Diego County, and Los Angeles County, among others.


Contact us at (714) 557–5077 or schedule an appointment for a complimentary roof inspection today.

Get a Quote

This is a Paragraph. Click on "Edit Text" or double click on the text box to start editing the content.

Thanks for submitting!

bottom of page