What is Torch-Down Roofing?

Torch-down roofing—also known as modified bitumen roofing—is one of the most reliable systems for flat and low-slope roofs. It consists of asphalt-based sheets reinforced with fiberglass or polyester. During installation, the sheets are rolled out and bonded to the roof with a propane torch, melting the underside and creating a seamless, watertight seal.
Torch-down roofing is typically installed as a two- or three-layer system:

Base Sheet – The foundation layer for adhesion and reinforcement

Cap Sheet – A top layer with UV and weather protection

(Optional) Interply Sheet – An extra layer in 3-ply systems for added durability

Why Torch-Down Roofing is a Great Choice for Alaska

Alaska’s extreme climate: heavy snow, freezing temperatures, ice dams, and thaw cycles, demands a roofing system that’s tough, flexible, and dependable.

Torch-down roofing delivers:

Cold Weather Flexibility: Modified bitumen remains pliable in sub-zero conditions, reducing the risk of cracks.

Waterproof & Ice-Resistant: Heat-welded seams create a tight seal, protecting against leaks during snowmelt and ice buildup.

Long-Lasting Durability: With expert installation, a torch-down roof can last 15–20+ years in Anchorage’s harsh conditions.

Low Maintenance: Requires less upkeep than traditional tar-and-gravel (BUR) systems.

Energy-Efficient Options: Reflective cap sheets reduce summer heat gain, helping lower energy costs in Alaska’s warming summers.

Torch-Down Roofing Systems & Base Sheet Options

Choosing the right base sheet is critical for performance and longevity. At General Roofing, we recommend the following based on your building type and needs:

Vented Base Sheet: Prevents blistering by allowing moisture to vent; excellent for reroofing in damp or coastal Alaska regions.

Mechanically Attached Base Sheet: Secured with fasteners instead of torching; safer for wood substrates and residential applications.

Self-Adhered Base Sheet: Peel-and-stick system that avoids open flames; a safer, faster option for homes.

Torch-Applied Base Sheet: Provides the strongest adhesion; ideal for commercial and industrial flat roofs.

Recommended Torch-Down Roof Systems for Alaska

Two-Ply System: Vented base sheet + torch-down cap sheet — a cost-effective balance of strength and performance.

Three-Ply System: Base sheet + interply + cap sheet — maximum durability for high snow-load areas, commercial buildings, or critical facilities.

Cap Sheet Selection: Granulated, UV-resistant cap sheets are recommended to withstand Alaska’s summer sun and prevent premature aging.

Safety & Professional Installation

Because torch-down roofing uses open flames, safety is a top priority. Our team follows strict fire-prevention protocols, and in some cases we recommend hybrid systems (torch + self-adhered) for added safety and performance.