Single-Ply Roofing
San Jose & the South Bay

Why Single-Ply Dominates Commercial Flat-Roof Work

Modern single-ply roofing combines the puncture resistance and flexibility of rubber membranes with the heat-weldable seams and reflective surface of thermoplastic chemistry. The result, developed through the 1990s and maturing through the 2000s, now has 25+ years of real-world performance data behind it. Formulations from the major manufacturers (Carlisle, GAF, Firestone, Johns Manville) deliver 20-30 year warranted service life with performance that generally exceeds expectations.

The reflective white surface is a significant benefit in the Bay Area climate. California Title 24 energy code requires cool-roof compliance on most commercial re-roofs (minimum 3-year aged solar reflectance of 0.55 for low-slope roofs). White TPO meets this handily, typically with aged reflectance of 0.65-0.70. The energy benefit is real and measurable: commercial buildings with bright white single-ply roofs experience measurably lower cooling loads, particularly during Bay Area summer afternoons.

Installation Methods: Mechanically-Fastened vs. Fully-Adhered

Single-ply systems install in two primary methods. Mechanically-fastened systems use plates and screws through the membrane into the deck, covered by the next membrane seam. Fastening pattern varies by wind-uplift zone (interior, perimeter, corner) and is dictated by the manufacturer's spec for the building's exposure category. Mechanically-fastened is cost-effective, faster to install, and the typical choice for most commercial buildings with steel or wood decks.

Fully-adhered systems use adhesive to bond the membrane directly to the insulation or cover board substrate. More expensive and slower to install, but eliminates visible fastener points and delivers better wind-uplift performance for high-exposure buildings. Also preferred for buildings sensitive to noise — wind flapping on mechanically-fastened membrane can be audible from indoors, which doesn't happen with fully-adhered work.

The Role of Insulation and Cover Board

Below the single-ply membrane, proper insulation matters significantly. California Title 24 prescribes minimum R-value (typically R-25 for the Bay Area's Climate Zone 3-4), delivered through polyisocyanurate (polyiso) insulation in 1-4 inch thickness depending on existing building insulation. For retrofits, we install above-deck insulation to meet current code requirements even when the original building was insulated to a lower spec.

Cover board — high-density polyiso, gypsum, or fiberboard layered above the insulation — provides puncture resistance and proper substrate for the membrane. Skipping cover board is a common shortcut that reduces long-term membrane performance, particularly on roofs with foot traffic or rooftop equipment. We don't skip it.