MFM Building Products has secured an additional Class A fire rating for its Ultra HT Wind & Water Seal roofing underlayment, expanding the product’s approved use in Wildland Urban Interface areas.

The Coshocton, Ohio-based manufacturer announced that the California State Fire Marshal has listed Ultra HT for use in W.U.I. zones when installed with Class A asphalt shingles. The approval falls under Listing No. 8180-2433:0001 in Category 8181 Non-Wood Roof Covering/Assemblies and meets applicable ASTM E108 requirements for Class A roof covering assemblies.

W.U.I. areas represent zones where residential or commercial development meets undeveloped land or vegetative fuel sources, creating elevated wildfire exposure risks. Building product performance in these environments continues to receive increased scrutiny as wildfire activity intensifies across multiple regions of the U.S.

Ultra HT is a 45-mil self-adhered roofing underlayment designed for steep-slope roofing and re-roofing applications. The product incorporates a cross-laminated polyethylene top film with a traction surface intended to improve walkability during installation. Its high-temperature adhesive formulation is rated to 250°F for demanding roofing environments.

The new California State Fire Marshal approval adds to existing fire performance certifications for the product, including UL 790 and ASTM E108/ICC-ES AC188 compliance.

MFM Building Products said additional roofing approvals and technical information are available through the company’s website.