Flat Roof Repair & Installation | East Bay
Low-Slope Systems That Actually Work

Flat Roofing in the East Bay

East Bay Roofers is the East Bay's licensed roofing contractor that homeowners and property managers call for flat and low-slope roofing Since 1988, we've installed TPO, EPDM, and modified bitumen systems for homes and businesses in Emeryville and across the East Bay. Here's what that looks like in practice:

What Is a Flat Roof, Really

A "flat" roof isn't actually flat. Under California Residential Code, anything with a slope less than 2:12 is classified as low-slope, and that's the category we're talking about. Even a roof that looks dead level to the naked eye has a quarter-inch-per-foot pitch built in, that's the minimum the code requires under CRC R905.11 through R905.14, and it's the minimum we'll install. Anything less, and water sits instead of moving. The system itself is a stack, not a single layer.

From the deck up, you've got insulation (usually polyisocyanurate boards, tapered to create slope), a cover board like DensDeck that protects the foam from foot traffic and fasteners, then the waterproofing membrane itself, TPO, EPDM, PVC, modified bitumen, or a multi-ply built-up system. Each layer has a job. Skip one, and the roof still works, until it doesn't.

When a Flat Roof Makes Sense

Flat roofs aren't a compromise. They're the right answer for a lot of situations. Room additions. When you push a bedroom out into the side yard and can't tie into the existing pitched roof without a structural nightmare, a low-slope membrane over the addition is the cleanest solution. We see this constantly in West Oakland Victorians where the original house has a steep hip roof and the 1970s addition has a flat section bolted onto the back. Mid-century modern homes. Berkeley Hills, Kensington, and parts of El Cerrito have entire streets of Eichler-era architecture where the flat roof is the design. You don't put shingles on an Eichler. You replace the original built-up roof with a modern single-ply and keep the house looking right. Commercial and multi-family. Almost every low-rise commercial building in Emeryville, downtown Walnut Creek, and the Richmond Iron Triangle is flat-roofed.

That's not an accident, it's cheaper to build, it gives you a mechanical platform, and it opens up solar real estate. Garages, carports, and covered patios. You don't need to complicate a 400 sq ft garage roof with valleys and hips. A modified bitumen cap sheet or a small TPO section does the job for a fraction of the cost.

Brands and Product Lines We Install

We're not married to a single manufacturer.

The right material depends on the deck, the slope, the exposure, and the budget. That said, here's what we actually keep on the truck. - Firestone/Holcim — UltraPly TPO and RubberGard EPDM. Firestone got absorbed into Holcim a couple years back, but the product lines are unchanged and the warranty is still solid. RubberGard is the single biggest EPDM product in the country and has been for 40 years.

• GAF Commercial, EverGuard TPO and EverGuard PVC, plus Ruberoid SBS and APP modified bitumen. We install GAF systems to manufacturer spec so they qualify for the strongest warranty coverage available.
• Carlisle SynTec, Sure-Weld TPO and Sure-Seal EPDM. Carlisle is the installer's favorite. Their detail accessories are the best in the industry, and their Syntec warranty process is straightforward.
• Johns Manville, JM TPO, JM EPDM, and DynaGlas modified bitumen. JM makes the insulation too, so you can spec a single-source warranty that covers the whole stack.
• Versico — VersiWeld TPO and VersiGard EPDM. Same parent as Carlisle, slightly different pricing.
• Soprema — SOPRALENE SBS modified bitumen. French system, heavy, bulletproof for residential flat decks.
• Henry — Blueskin cap sheets and a full line of coatings and roof cements.

Installation — What Actually Happens

Every flat-roof job we do follows the same sequence.

It's not glamorous, but it's the reason the roofs don't leak. 1. Tear off to sound decking. If the plywood is wet, swollen, or delaminating, it gets replaced. No exceptions. We don't lay a new membrane over rotted substrate and hope for the best. 2. Install insulation. Tapered polyiso boards, mechanically fastened or adhered depending on the deck. We verify the slope with a string line and a level before the next layer goes on. 3. Cover board — usually DensDeck Prime or a high-density wood fiber board. This is where a lot of cheap jobs skip a step, and it shows up as punctures five years later. 4. Membrane installation. Heat-welded, fully adhered, mechanically attached, or ballasted depending on the system. Every seam gets probed after it cools. 5. Flashings. Parapet walls, pipe penetrations, HVAC curbs, drains, scuppers. This is where 90% of flat-roof leaks start, so this is where we slow down. 6. Walkway pads at service points so the HVAC tech doesn't puncture the membrane with a ladder leg. 7. Flood test (on new construction and warranty work) before signoff.

Code Requirements

California Residential Code covers low-slope roofing in sections R90 5.11 through R905.14, with each membrane type getting its own subsection.

CRC R905.12 is EPDM, R905.13 is TPO, R905.14 is modified bitumen. Every system we install meets ASTM D6878 (TPO), D4637 (EPDM), or D6162/6163/6164 (modified bitumen) depending on the material. Then there's California Title 24, which mandates cool-roof performance on most low-slope roofs, initial solar reflectance of 0.63 or higher for roofs over buildings with air conditioning. White TPO and PVC hit that spec right out of the roll. Black EPDM doesn't, so if Title 24 applies and your engineer won't give you a workaround, EPDM is off the table unless you add a reflective coating. Fire rating matters too. Any structure near a Wildland Urban Interface zone needs a Class A assembly under Chapter 7A, which affects flat roofs the same way it affects shingles. We detail the assembly accordingly when we're in the hills.

East Bay Cities Where Flat Roofing Works Best

Flat and low-slope systems are the default in a handful of neighborhoods we work in constantly: - Emeryville, almost entirely commercial flat roofs, mostly TPO and PVC.

• Downtown Walnut Creek and Pleasant Hill — older retail blocks with modified bitumen and BUR systems being replaced with TPO.
• West Oakland and Berkeley. Victorian and craftsman homes with flat additions on the back, usually torch-down or EPDM.
• Richmond Iron Triangle — mix of commercial, industrial, and multi-family, heavy on EPDM and built-up systems.
• Kensington, El Cerrito Hills, and Berkeley Hills — mid-century moderns where the original flat roof is part of the architecture. We're licensed across all three counties we serve. Contra Costa, Alameda, and Marin — and pull permits in every jurisdiction weekly.

Get a Real Flat-Roof Assessment

If you've got a flat section that's leaking, ponding, or just getting old, call East Bay Roofers at (925) 722-4916.

We'll come out, look at the existing assembly, tell you what system actually makes sense for your building, and give you a written quote you can compare against anyone else's. No pressure, no upsell, just a contractor who's been doing this since 1988. , C-39,.

What Flat Roofing Includes

Flat roofs are all about drainage and flashing. We inspect the deck — plywood or osb — for rot and level, replace damaged sheathing, then lay underlayment before the membrane. The critical details are the edges and penetrations: drip edge and fascia metal at the perimeter, vent boot collars at every pipe, and flashing where the roof meets walls and parapets. Seams get welded or mastic-bonded per the membrane type, and we verify the slope meets building code for ponding. Gravel, old membrane, and debris go to the dumpster.

Roof System Details

Beyond the visible work, every flat roofing project on a roof touches the same system-level details. Valleys are flashed with corrosion-resistant metal so the heaviest water flow stays off the deck. Ice dams are addressed at the source — ice-and-water shield in the eaves and lower field plus balanced ridge vent and soffit vent airflow keeps the deck temperature even, so snowmelt doesn't refreeze at the eave and push water up under the shingles. The joist and rafter structure is checked for deflection before heavy materials go up. Gutter and downspout connections are confirmed at the eaves so the roof edge drains into the system instead of behind it — a roof and its gutters are one water-shedding assembly, and we treat them that way.

Quality & Materials Standards

Every material we install is specified to a standard, not just a price. Architectural shingles and three-tab shingle options are dimensional fiberglass-backed products with granulated mineral surfacing; standing-seam panel and corrugated panel metal roofs come in steel or aluminum with elastomeric coating options (including acrylic coating and silicone coating where the spec calls for them). TPO, EPDM, and built-up roof membranes are checked for tensile strength and coverage rate before they go up. Adhesive and roof cement are used where the membrane spec requires them, and fasteners are driven to the manufacturer's exact coverage rate — never guessed.

We also inspect for the failure modes that shorten roof life, and we're honest about what we find: blistering and blisters, buckling or warping, delamination and spalling, corrosion and erosion of metal, granulated loss, UV degradation, and deterioration that shows as flaking, cracking, or seepage at seams and eaves. Water that wicks up under a substrate rots sheathing and trusses; we fix the substrate, not the symptom. Drains, downspouts, and gutters are checked as part of the water path — a roof that drains is a roof that lasts.

Storm response is built into our process: hail damage and wind damage assessments document every dent, dislodged shingle, and lifted flashing for the adjuster. We handle claim documentation — including the deductible line items, depreciation schedules, and supplement paperwork insurance companies require — so the scope of work is approved before the crew arrives, and a tarp protects the interior until the permanent repair is scheduled. Crews work to a written scope of work with scaffold and safety harness protocols on every steep roof.