Ply 4

Why GAFGLAS® Ply 4 Sheet?

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
  • Asphalt coating provides high degree of moisture resistance
  • Fire resistant for use in UL Class A rated assemblies
  • Wind uplift resistance; selected roofing assemblies with GAFGLAS® Ply 4 felts meet FMRC Class 1-180 when installed over concrete decks
  • Meets ASTM D-2178, Type IV specifications
  • Can be used in all climate zones Rolls out flat for easy installation  


GAFGLAS® Ply 4 Ply Sheet is used as a ply felt in the construction of built-up roofs. It is designed for use in all climate zones and is appropriate for use as a base sheet, as a ply felt, and in the construction of flashing membranes.


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