Flat Roofing
Low-Slope Systems That Actually Work

Flat Roofing Done Right

Flat roofs aren't inherently problematic — poorly installed ones are. The East Bay has thousands of flat and low-slope roofs on mid-century modern homes, commercial buildings, room additions, and garages that perform flawlessly for decades. The difference between a leaking flat roof and a reliable one comes down to three things: material selection, drainage design, and installation quality.

Flat Roof Systems Compared

TPO (Thermoplastic Polyolefin) — Single-ply membrane heat-welded at seams. White surface reflects solar heat — meets California Title 24 cool roof requirements without additional coatings. Seams are stronger than the membrane itself. Most popular for commercial and larger residential flat sections. 20-30 year warranties from manufacturers like Carlisle, Firestone, and GAF.

EPDM (Ethylene Propylene Diene Monomer) — Synthetic rubber membrane, typically black. Extremely flexible — handles building movement, temperature swings, and irregular surfaces better than any other membrane. Seams are taped and adhesive-bonded. Available in 45-mil and 60-mil thicknesses. Preferred for irregular roof shapes, rooftop decks, and when maximum durability matters.

Modified Bitumen — Asphalt-based membrane reinforced with polyester or fiberglass. Applied by torch, hot-mopped, or self-adhered (peel-and-stick). Multi-layer systems (base + cap sheet) provide redundancy. Familiar technology that roofers have used for 50+ years. Best for residential flat sections, covered patios, and smaller commercial buildings.

Built-Up Roofing (BUR) — Multiple alternating layers of bitumen and reinforcing fabric topped with gravel or a cap sheet. The original flat roofing system. Still used on commercial buildings where maximum puncture resistance is needed. Being gradually replaced by single-ply systems that are lighter and faster to install.

Common Flat Roof Applications in the East Bay

Room Additions — When you extend a home horizontally and can't tie into the existing slope, a flat membrane roof over the addition is the practical solution. We tie into the house wall with proper counter-flashing and ensure drainage flows away from the existing structure.

Mid-Century Modern Homes — The East Bay has a rich stock of mid-century modern architecture, particularly in the hills of Oakland, Berkeley, and El Cerrito. These homes were designed with flat roofs as an architectural feature. We maintain the original aesthetic while upgrading to modern membrane systems.

Garages & Carports — Detached garages and carport structures commonly have flat or very low-slope roofs. Modified bitumen or EPDM provides decades of protection at reasonable cost.

Commercial Buildings — Retail, office, and warehouse buildings throughout Concord, Pleasanton, Dublin, and Fremont rely on flat roofing systems. TPO is the commercial standard for its energy efficiency, durability, and competitive installed cost.

The Drainage Challenge — And How We Solve It

Water pools on a flat roof because it has nowhere to go. Our solution starts at the design stage: tapered rigid insulation boards create a minimum 1/4 inch per foot slope toward drain locations. Internal drains, scuppers through parapet walls, or controlled-flow roof edges give water a clear exit path. After installation, we flood-test every roof section to verify positive drainage before your final walkthrough.