CertainTeed Glasbase Base Sheet is designed for use as a base sheet for both hot and cold applied, inorganic built-up roofing systems. It is suitable for use in the construction of various types of membranes for both new construction and reroofing, over a variety of substrates. Glasbase Base sheet will provide additional strength, moisture resistance and asphalt uniformity when used as the first ply over nailable, non-nailable and insulated substrates. In addition, it will perform as a venting base sheet when spot mopped over plastic foam type insulations.

Technical Information

CertainTeed Glasbase Base Sheet is manufactured on an extra strength fiberglass reinforced mat that receives a coating of weathering grade asphalt and is lightly surfaced with a mineral release agent. The fiberglass base mat provides excellent strength and moisture resistance. Glasbase Base Sheet is pliable and will confirm to most surfaces for easy of application.

  • Support Mat: Wet process fiber glass mat
  • Surfacing: Fine sand, release agent
  • Weight: 75 lbs. per roll
  • Dimensions: 39-3/8" x 98' 9" (324 sq. ft.)
  • Coverage: Three Square
  • Thickness: 1.0mm (40 mils)
  • ASTM D4601, Type II
  • UL Type G2

For additional technical resources please refer to the CertainTeed Commercial Roof Systems Manual.


CertainTeed Glasbase Base Sheet may be applied in either hot asphalt or approved cold adhesive such as CertainTeed's FlintBond™, depending on system design and selection. Rolls should be stored upright, off ground, completely protected from the weather. Roof decks shall be structurally sound, dry, smooth and meet or exceed minimum requirements of the deck manufacturer, local code and CertainTeed.

For detailed installation instructions please refer to the CertainTeed Commercial Roof Systems Manual.

Warranty Details

CertainTeed backs its commercial roofing systems with the confidence of three warranty choices:

Limited Product Warranty

NDL Roof Membrane Limited Warranty*

Full System NDL Limited Warranty*

Owners and specifiers who choose the NDL or Full System NDL warranty options have the added security of manufacturer involvement in the sometimes difficult process of contractor qualifying and workmanship inspection. Consult with the roofing contractor and your CertainTeed commercial roofing territory manager to decide which CertainTeed warranty is best for your building or project.

*NDL warranties are not available on all specifications and are only available through CertainTeed Gold and Silver Star Contractors

Commercial Roofing Contractors

See All Contractors near You
Get Started