Calculate cubic yards, bags needed, and Concord CA-accurate ready-mix costs for driveways, patios, ADU slabs, foundations, retaining walls & more in Contra Costa County and the East Bay.
Enter project dimensions to calculate volume, bags, and estimated Concord CA material cost.
Concord is in Seismic Zone 4. All structural concrete requires CBC-compliant seismic anchor bolts, continuous footings, and engineered rebar. Contact City of Concord Building Division at (925) 671-3152 before any structural pour.
Patio 4 in · Driveway 4–5 in · Garage 4–5 in · ADU slab 4–6 in · Commercial 5–6 in · Foundation per engineer · Footing 12–24 in
Concord is the largest city in Contra Costa County, located in the East Bay at the foot of Mount Diablo in the Diablo Valley. As a Bay Area city in Seismic Design Category D (Zone 4), Concord faces California's most demanding structural concrete requirements. The city sits in a geologically active corridor bounded by the Concord–Green Valley Fault (capable of a Magnitude 6.9 earthquake) to the east and the Calaveras Fault to the west, with the Hayward Fault just 10 miles southwest. All structural concrete in Concord — foundations, footings, retaining walls over 4 ft, and any slab supporting a structure — must comply with California Building Code (CBC) 2022 Chapter 19A seismic provisions, including continuous footings, prescribed rebar spacing, and seismic anchor bolts connecting the concrete to wood framing. Additionally, Contra Costa County's interior valleys experience dry, hot summers (95–105°F in August) and wet winters, driving the same expansive clay soil movement that causes premature concrete cracking throughout the East Bay foothills and Diablo Valley floor.
Residential outdoor flatwork: 3,000 PSI min · Structural slabs, foundations, ADU: 3,000–3,500 PSI, CBC Chapter 19A seismic provisions, engineered rebar, continuous perimeter footings, seismic anchor bolts · Retaining walls over 4 ft: Engineer design + Concord building permit required · CalGreen Title 24: 10-mil ASTM E1745 Class A vapor barrier under all interior slabs · ADU / JADU: Full CBC foundation and structural compliance required. Verify all requirements with City of Concord Building Division at (925) 671-3152.
Multiply length × width × (depth in inches ÷ 12) to get cubic feet, then divide by 27 for cubic yards. Always add a minimum 10% waste factor — Bay Area short-load fees of $120–$200 for orders under 3–5 cubic yards are among the highest in the country, given California's high trucking and operating costs. Hot Concord summers mean scheduling large pours before 7 AM from June through September — August temperatures in the Diablo Valley regularly exceed 100°F, which can accelerate concrete set time enough to cause placement and finishing problems within 30–45 minutes of discharge. Always use a set retarder admixture (ASTM C494 Type B or D) on pours exceeding 5 cubic yards during warm weather.
Concord is one of the highest-seismic-risk cities in the United States for a metropolitan area of its size. The Concord–Green Valley Fault is a Type A active fault under California's Alquist-Priolo Earthquake Fault Zone Act — any new habitable structure within 50 ft of the fault centerline requires a geotechnical investigation. For all structural concrete (foundations, footings, retaining walls), you must: obtain a City of Concord building permit before breaking ground; follow CBC 2022 Chapter 19A seismic concrete provisions; install #4 rebar at 16 in. o.c. (vs. the standard #3 at 18 in. used in non-seismic markets); embed seismic anchor bolts (½ in. diameter, 7 in. embedment) at 6 ft o.c. maximum in all sill plates; and pour continuous footings minimum 12 in. wide × 12 in. deep for one-story, 15 in. wide × 18 in. deep for two-story structures. Additionally, Contra Costa County's expansive clay soils require a licensed geotechnical engineer's soils report for any new foundation — budget $1,500–$3,500 for the report before design.
Concord and the Contra Costa East Bay are served by Cemex, Central Concrete (a US Concrete company), and several independent Bay Area ready-mix plants in the I-680, SR-4, and SR-24 corridors. Bay Area concrete pricing is among the highest in the United States — driven by California's AB 32 and SB 32 environmental compliance costs, CARB diesel emissions surcharges on mixer trucks, high labor costs under prevailing wage for any public-works-adjacent work, and limited new plant permitting. Antioch and Pittsburg (eastern Contra Costa) may have slightly lower pricing at $155–$172/yd, while Walnut Creek and Orinda (western, closer to Oakland) run $165–$195/yd.
| Mix / PSI | Concord CA Price / Cu Yd | National Avg | Best For | Seismic Rebar? | CBC Code |
|---|---|---|---|---|---|
| 3,000 PSI — CBC Minimum | $148–$168 | $125–$145 | Patios, simple flatwork, interior slabs | #3 minimum | Compliant |
| 3,500 PSI — East Bay Standard | $158–$178 | $135–$155 | Driveways, garage slabs, ADU slabs, all exterior | #4 seismic req. | Compliant |
| 4,000 PSI — Seismic Structural | $168–$192 | $145–$165 | Foundations, retaining walls, commercial slabs | #4–#5 required | Compliant |
| 5,000 PSI — Industrial / Tilt-Up | $185–$215 | $163–$185 | Tilt-up panels, industrial floors, heavy commercial | Eng. design req. | Compliant |
| Fiber / Decorative / Stamped | $175–$240 | $150–$210 | Decorative patios, stamped driveways, pool decks | Fiber + #4 | Compliant |
Concord averages $158–$178/yd for 3,500 PSI with I-680 plant access. Walnut Creek (south, upscale market) runs $165–$188/yd — higher due to prevailing wage influence on adjacent commercial projects. Antioch and Pittsburg (east, SR-4 corridor) run $148–$168/yd — the most affordable in Contra Costa given plant proximity and lower demand pressure. Martinez (county seat, west) runs $158–$180/yd. Orinda and Moraga (Lamorinda hills) see $175–$210/yd due to hillside access surcharges and longer haul distances. For all Concord pours over 7 cubic yards, call Cemex or Central Concrete 24–48 hours ahead — Bay Area plants run near capacity April through October.
City of Concord, Contra Costa County, CalTrans, and CBC references for compliant seismic concrete work across the East Bay.
Apply for Concord building permits for foundations, ADU slabs, retaining walls, garage slabs, commercial structural pours, and driveway connections throughout the City of Concord. Schedule footing, slab, and rebar inspections. Verify current CBC 2022 seismic concrete requirements, Alquist-Priolo Earthquake Fault Zone setback rules for the Concord–Green Valley Fault, CalGreen Title 24 vapor barrier and sub-base requirements, and Contra Costa County floodplain development rules for project sites near Galindo Creek and Ygnacio Canal drainage corridors. Contact City of Concord Building Division at (925) 671-3152 for permit applications, fee schedules, standard seismic detail drawings, and all residential and commercial concrete inspection scheduling in Concord, CA.
Visit Concord Building DivisionAccess California Geological Survey (CGS) Alquist-Priolo Earthquake Fault Zone maps for Concord and Contra Costa County, identifying fault trace setback zones for the Concord–Green Valley Fault, Calaveras Fault, and other active faults affecting East Bay concrete foundations and structures. Download seismic hazard zone maps, liquefaction and landslide susceptibility data for Contra Costa County soils, and CGS Special Publications on geotechnical investigation requirements for CBC Seismic Design Category D construction. The CGS Earthquake Zones of Required Investigation database is essential for any structural concrete project in Concord requiring a site-specific geotechnical report under CBC 2022 Chapter 18A soils and foundations provisions.
Visit California Geological SurveyAccess Caltrans Standard Specifications for concrete construction in the Contra Costa County area — including Class II aggregate base compaction standards for East Bay expansive clay subgrade, concrete mix design requirements for California's hot interior valley climate zones, driveway access permit applications for SR-4, SR-242, I-680, and I-680/SR-4 interchange corridor commercial and residential properties, and Caltrans standard detail drawings for sidewalk, curb, gutter, and driveway approach concrete work adjacent to state right-of-way in Concord and western Contra Costa County. Caltrans District 4 (Bay Area) oversees all state highway-adjacent concrete permitting and inspection for Concord and surrounding East Bay communities.
Visit Caltrans District 4