Torch-on Waterproofing Systems

Torch-on waterproofing systems, also known as torch-applied waterproofing systems or torch-down roofing, are a popular method for creating a waterproof barrier on various surfaces, including roofs, decks, and other construction elements. These systems use modified bitumen membranes that are heated with an open flame torch during installation, creating a durable, watertight seal. Here’s an overview of torch-on waterproofing systems:

Components of Torch-On Waterproofing Systems:

  1. Modified Bitumen Membrane: The core component of a torch-on system is the modified bitumen membrane. This membrane is typically made of layers of asphalt or bitumen combined with modifiers such as rubber or plastic. The modifiers enhance the membrane’s flexibility, strength, and waterproofing properties.
  2. Reinforcement: Some torch-on membranes include a reinforcement layer, often made of fiberglass or polyester, to provide additional strength and dimensional stability.
  3. Surface Finish: The top surface of the membrane may have a variety of finishes, including mineral granules, reflective coatings, or a smooth surface, depending on the application and aesthetic preferences.

Installation Process:

  1. Surface Preparation: The surface to be waterproofed must be thoroughly cleaned, free of debris, and prepared to ensure proper adhesion. Any existing cracks or defects should be repaired before membrane installation.
  2. Primer Application: A primer is often applied to the surface to enhance the bond between the substrate and the membrane. The choice of primer depends on the type of substrate and the specific torch-on membrane being used.
  3. Membrane Application: The modified bitumen membrane is rolled out onto the prepared surface. It is then heated using an open flame torch or hot air gun. The heat softens the bottom of the membrane, allowing it to adhere securely to the substrate.
  4. Seam Sealing: Overlapping seams between adjacent membrane rolls are heated and pressed together to create a waterproof seal. Some systems use a separate melting agent or adhesive to achieve seam bonding.
  5. Detailing: Special attention is given to details such as penetrations, edges, and corners. These areas are sealed using additional membrane layers and are heated to ensure a watertight seal.
  6. Protection Layer (Optional): In some applications, a protective layer, such as gravel or pavers, may be added to the top of the torch-on membrane for UV resistance and added durability.
  7. Quality Assurance: Quality control checks are performed throughout the installation process to verify proper adhesion, seam integrity, and overall waterproofing effectiveness.

Advantages of Torch-On Waterproofing Systems:

  • Excellent waterproofing capabilities.
  • Durability and longevity.
  • Resistance to UV radiation and weathering.
  • Flexibility to accommodate building movement.
  • Suitable for various substrates and applications.


  • Proper installation by experienced professionals is essential for optimal performance.
  • Safety precautions must be taken when using open flames during installation.
  • Maintenance and periodic inspections are necessary to ensure the system’s ongoing effectiveness.

Torch-on waterproofing systems are commonly used in both residential and commercial construction for their reliability and waterproofing capabilities. They are particularly popular for flat or low-slope roofs and decks but can also be used in various other applications where reliable waterproofing is required.