About GAFGLAS® Ply 4

Constructed with a strong glass fiber mat coated with the finest quality asphalt, this base sheet is designed with optimum porosity to assure a sound, watertight membrane. It has a high tensile strength and high degree of dimensional stability, resulting in a roof system with greater resistance to splitting and cracking. Typical system guarantees available for up to 15 years; select system constructions available with up to 20 year guarantee coverage.

  • Optimum felt porosity provides ready escape of air while allowing proper asphalt penetration at the time of mopping
  • Meets ASTM D-2178, Type IV specifications
  • Can be used in all climate zones Rolls out flat for easy installation  

Features and Benefits

Product Documentation


SBS, APP & BUR roof system product comparisons

Any discussion on asphaltic roofing will involve one or more of these three terms: SBS (Styrene-Butadiene-Styrene), APP (Atactic Polypropylene), and BUR (Built-up roofing). SBS and APP are polymers with unique characteristics, and membranes made with them are classified by ASTM numbers, types and grades. BUR is an assembly method in which multiple layers of felts are installed with hot asphalt in-between.

Asphaltic Membrane Installation Methods

One of the many reasons asphaltic roofing remains so popular is the wide variety of installation methods available. Depending on specifications, building characteristics and use cases, asphalt roofs can be hot-mopped, heat-welded/torch-applied, cold-applied (adhered), self-adhered, or mechanically attached. Find more about these techniques.
Asphaltic Roofing 101 Playlist from GAF Commercial

Asphaltic Commercial Roofing 101

Proven historical performance. Time tested durability. Asphaltic roofing products are a go-to material of choice for high end low-slope buildings. Learn more about asphaltic technologies and application techniques, as well as how to decide if asphaltic is the right roofing solution for your next project.

Resources for every professional

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