Torch Down Roofing
Modified Bitumen — Proven Flat Roof Protection
Torch-down modified bitumen roofing for East Bay flat and low-slope roofs. Multi-layer waterproofing, 20-25 year lifespan, and superior puncture resistance. Licensed installers.
Call (925) 722-4916 NowThe Workhorse of Flat Roofing
Torch-down modified bitumen has been the go-to flat roofing system for East Bay homes since the 1980s. It's not flashy. It doesn't have a marketing department. But it works — reliably, predictably, and affordably. For garage roofs, room additions, covered patios, and small commercial buildings, torch-down delivers serious waterproofing at a reasonable price.
Puncture Resistant
Multi-layer membrane with reinforced polyester or fiberglass. Handles foot traffic, dropped tools, and hail better than single-ply alternatives.
Fused Seams
Torch-welded overlaps create monolithic waterproof bonds. No adhesives to fail, no tape to delaminate. Seams are as strong as the membrane.
Easy to Repair
Localized damage patched on the spot with matching membrane and a torch. No full-sheet replacements needed for isolated punctures or cuts.
Fast Installation
A typical residential flat section (300-800 sq ft) completed in one day. Multi-layer commercial systems in 2-3 days per 3,000 sq ft.
How Torch-Down Works
Modified bitumen is asphalt blended with polymers — either APP (atactic polypropylene) or SBS (styrene-butadiene-styrene) — that make it flexible and resistant to temperature extremes. The membrane comes in rolls, typically 39 inches wide, with a thermoplastic backing.
APP-Modified (Torch Applied) — The traditional method. A propane torch heats the membrane backing as it's unrolled, melting the bitumen layer into a waterproof bond with the substrate below. The result is a continuous, sealed membrane with no gaps or adhesive layers that can fail. APP membranes excel in heat resistance and UV stability.
SBS-Modified (Flexible) — SBS polymer gives the membrane rubber-like elasticity. More flexible than APP at low temperatures, making it better for roofs that experience significant thermal cycling. Can be torch-applied, hot-mopped, or cold-adhered with specialty adhesives. SBS membranes are preferred when building movement or extreme temperature ranges are expected.
Our Installation System
Layer 1: Substrate Preparation — Existing roof stripped to clean, sound decking. New plywood or cover board installed where needed. Tapered insulation creates positive drainage slope (minimum 1/4" per foot).
Layer 2: Base Sheet — Mechanically fastened or torch-applied base sheet provides the structural membrane layer. Polyester-reinforced for high tensile and tear strength. All penetrations (pipes, drains, HVAC curbs) receive custom flashings at this stage.
Layer 3: Cap Sheet — Granulated cap sheet torch-applied over the base. The granule surface provides UV protection, fire resistance, and slip-resistant walking surface. Laps are torched 6 inches minimum with full bitumen bleed-out at seams.
Optional Layer 3.5: Interply Sheet — On premium three-layer systems, an interply (smooth) membrane between the base and cap adds redundancy. If the cap sheet is ever punctured, the interply provides a secondary waterproof barrier.
Maintenance for Maximum Life
Torch-down roofs require minimal but consistent maintenance:
- Annual inspection — Check seams, flashings, and membrane surface for cracks or blisters. Fall is ideal timing.
- Drain clearing — Keep internal drains, scuppers, and gutters free of debris. Standing water accelerates membrane aging.
- Sealant refresh — Roof cement at penetration flashings dries out every 5-8 years. Re-sealing takes 30 minutes and prevents expensive repairs.
- Coating (optional) — Aluminum reflective coating applied at year 10-15 extends membrane life by 5-8 years and improves energy performance.
With proper maintenance, a two-layer torch-down system installed on an East Bay flat roof consistently delivers 20-25 years of leak-free performance. We have customers with torch-down roofs from 2002 that are still going strong.
Torch Down Costs
Single-Layer Cap
One cap sheet over existing base. Best for re-covering a sound existing roof. 15-year warranty.
Two-Layer System
Base sheet + cap sheet over new insulation. Standard for complete flat roof replacement. 20-year warranty.
Three-Layer Premium
Base + interply + cap sheet with granulated surface. Maximum protection and 25-year warranty. Best for larger areas.
Frequently Asked Questions
Is torch-down roofing safe?
In the hands of trained installers, yes. The open flame from the torch melts the bitumen backing, creating a fused bond stronger than adhesive methods. Our crews are certified in torch application, carry fire extinguishers, and use fire-watch protocols during and after installation. We also offer cold-applied modified bitumen (peel-and-stick) for situations where open flame isn't appropriate.
How does torch-down compare to TPO?
Torch-down (modified bitumen) is thicker, more puncture-resistant, and easier to repair. TPO is lighter, more reflective, and better for very large areas. For residential flat sections under 1,000 sq ft — garage roofs, room additions, covered patios — torch-down is often the better choice due to its simplicity and proven track record.
Can I walk on a torch-down roof?
Yes. Modified bitumen membranes with granulated surfaces handle foot traffic well. For regular access areas (HVAC service, rooftop equipment), we recommend walk pads for additional protection. The granulated surface also provides traction in wet conditions.
What causes torch-down roofs to fail?
Seam separation from improper torch technique (not enough heat), ponding water from inadequate slope, and UV degradation on non-granulated surfaces. A well-installed torch-down system with proper drainage fails from age, not defects — it simply dries out and becomes brittle after 20-25 years.
Get Your Free Roof Inspection
Call today for a no-obligation estimate from a licensed East Bay roofing contractor.
Call (925) 722-4916When Torch-Down Isn't the Right Call
If your flat roof is over 3,000 sq ft, TPO or EPDM is usually more cost-effective per square foot and faster to install. If energy efficiency is a priority, the dark granulated surface of torch-down absorbs more heat than a white TPO membrane. And if your building has combustible materials near the roof edge (wood siding, overhanging trees), the open-flame torch application creates a fire risk that cold-applied alternatives avoid.
Related Services
Flat Roofing
Overview of all flat roofing systems — TPO, EPDM, and modified bitumen compared.
TPO Roofing
Energy-efficient alternative for larger flat roof areas.
EPDM Roofing
Rubber membrane option with maximum flexibility and 30-year durability.
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From Concord to Fremont, Oakland to San Ramon — East Bay Roofers covers the entire East Bay.
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