| Custom Building LP | Timothy Alan Gould | — | (925) 999 4404 | GC, remodel, ADU | Dublin · Alameda County | — | — |
| Custom Cal Drywall And Stucco | Armando Marquez | — | (510) 387 4729 | Other | Hayward · Alameda County | — | — |
| Custom Construction Co | Kantorov Ilya | — | (510) 918 8281 | Electricians | Hayward · Alameda County | — | — |
| Custom Construction Solutions | Zachary Z Petit | — | (925) 596 1069 | Other | Pleasanton · Alameda County | — | — |
| Custom Contracting Services | Paul Anthony Kardash | — | (510) 520 3669 | Other | Oakland · Alameda County | — | — |
| Custom Exchange Windows | Michal Pawel Kuron | — | (925) 518 3103 | Windows, patio, painters | Pleasanton · Alameda County | — | — |
| Custom Exteriors INC | Jeffrey Edward Kendall | info@custom-exteriors.com | (925) 249-2280 | GC, remodel, ADU | Pleasanton · Alameda County | — | — |
| Custom Home Theater | Custom Home Theater | — | (510) 461 8068 | Other | Fremont · Alameda County | — | — |
| Custom Innovations | Custom Innovations | info@custom-innovations.com | (510) 265 4742 | Windows, patio, painters | Castro Valley · Alameda County | — | — |
| Custom Interior Woodwork | Custom Interior Woodwork | — | (925) 606 7260 | Other | Pleasanton · Alameda County | — | — |
| Custom Landscapes | Brian Wayne Fenske | — | (510) 549 3954 | Windows, patio, painters | Berkeley · Alameda County | — | — |
| Custom Painting INC | Jason James Dewitt | info@custompainting.com | (925) 443 3500 | Windows, patio, painters | Livermore · Alameda County | — | — |
| Custom Prefabricated Fireplace | Andrew Martin Ligon | — | (925) 829 6360 | Other | Dublin · Alameda County | — | — |
| Custom Quality Painting | Custom Quality Painting | — | (510) 437 9192 | Windows, patio, painters | Oakland · Alameda County | — | — |
| Custom Remodeling Natural Stone And Tile Contractors | Shawn Clayton Lamont | — | (408) 348 0891 | Other | Fremont · Alameda County | — | — |
| Custom Stone Bg INC | Dimitar Nikolov Marchev | — | (510) 667 0099 | GC, remodel, ADU | San Leandro · Alameda County | — | — |
| Custom Tile & Stone | Custom Tile & Stone | — | (650) 766 2724 | Other | Fremont · Alameda County | — | — |
| Custom Tile INC | Joel Ernesto Ramirez | — | (510) 962 0895 | Other | Castro Valley · Alameda County | — | — |
| Custom Trim Concepts | Custom Trim Concepts | — | (650) 346 0244 | Other | Hayward · Alameda County | — | — |
| Custom Woodworking | Custom Woodworking | — | (925) 413 3380 | Other | Livermore · Alameda County | — | — |
| Cut Clean Dry Restore INC | Lexin Shan | — | (510) 999 8840 | GC, remodel, ADU | Hayward · Alameda County | — | — |
| Cut Once Construction | Michael Nicholas Pavis | — | (925) 233 9000 | GC, remodel, ADU | Livermore · Alameda County | — | — |
| Cutter Sewer And Sanitation Systems | Cutter Sewer And Sanitation Systems | — | (510) 467 2732 | Other | Oakland · Alameda County | — | — |
| Cutting Edge Countertops INC | Mark Daniel Hubbard | cuttingedgetops@aol.com | (925) 425 7710 | Other | Pleasanton · Alameda County | — | — |
| Cutting Edge Painting LLC | Chad Hunter Feagley | — | (510) 410 8185 | Windows, patio, painters | Oakland · Alameda County | — | — |
| Cv Glass | Cv Glass | — | (925) 457 4878 | Windows, patio, painters | Hayward · Alameda County | — | — |
| Cw Lance LLC | Todd Lance Neizman | — | (925) 413 9944 | Other | Livermore · Alameda County | — | — |
| Cx Construction | Chen Xiang | info@cxconstruction.com | (510) 579 8059 | GC, remodel, ADU | Hayward · Alameda County | — | — |
| Cxd Construction | Cash Cypress Davis | info@cxdconstruction.com | (510) 637 8002 | GC, remodel, ADU | Piedmont · Alameda County | — | — |
| Cypress Contracting Corp | Christopher Gomez Leon | — | (510) 586 0058 | GC, remodel, ADU | Pleasanton · Alameda County | — | — |
| Cyril Skladany | Cyril Skladany | — | (408) 394 6639 | GC, remodel, ADU | San Leandro · Alameda County | — | — |
| D & A Custom Painting INC | Daniel Ayala-Molina | — | (408) 971 1142 | Windows, patio, painters | Hayward · Alameda County | — | — |
| D & C Glass And Aluminum INC | Michael Norman Carvin | — | (925) 425 7671 | Windows, patio, painters | Pleasanton · Alameda County | — | — |
| D & C Owl Landscape INC | Diana Elizabeth Magana | — | (408) 509 0588 | Windows, patio, painters | Fremont · Alameda County | — | — |
| D & D Commercial & Residential Painting Incorporated | David Earl Rice | — | (925) 426 9214 | Windows, patio, painters | Pleasanton · Alameda County | — | — |
| D & D Construction And Development INC | John Zeng Yuan Xu | — | (510) 579 2353 | GC, remodel, ADU | Fremont · Alameda County | — | — |
| D & E Granite And Marble INC | Dorus Lai Ng | — | (510) 207 3210 | Other | Hayward · Alameda County | — | — |
| D & H Construction | Marshall Lee Snow | — | (510) 237 7883 | GC, remodel, ADU | Berkeley · Alameda County | — | — |
| D & H Painting | D & H Painting | — | (510) 471 3330 | Windows, patio, painters | Union City · Alameda County | — | — |
| D & M Builders | Steven Mickel Botelho | — | (510) 862 3414 | GC, remodel, ADU | Castro Valley · Alameda County | — | — |