| Castellanos Construction | Castellanos Arango Fortino | — | (707) 494 0989 | GC, remodel, ADU | Santa Rosa · Sonoma County | — | — |
| Castelli Construction | Stephen John Castelli | — | (707) 363 6447 | GC, remodel, ADU | Sonoma · Sonoma County | — | — |
| Castillo Electrical Services | Manuel James Castillo | — | (831) 320 7825 | Electricians | Santa Rosa · Sonoma County | — | — |
| Castino Restaurant Supply | David Gregg Jr Castino | — | (707) 585 3566 | GC, remodel, ADU | Rohnert Park · Sonoma County | — | — |
| Castle Concrete Pumping INC | Obadiah Sterling Elliott | — | (707) 528 7867 | Other | Santa Rosa · Sonoma County | — | — |
| Castle Construction | Thomas Steven Castellino | — | (707) 527 9231 | GC, remodel, ADU | Santa Rosa · Sonoma County | — | — |
| Castle Contracting | Charles Vall Castle | — | (604) 835-2075 | GC, remodel, ADU | Petaluma · Sonoma County | — | — |
| Castle Heating & Air | Richard Noe Castillo | castleheatingandair@yahoo.com | (707) 953 6261 | HVAC | Petaluma · Sonoma County | — | — |
| Castor Construction | Patrick Raymond Castor | — | (707) 480 8182 | GC, remodel, ADU | Sebastopol · Sonoma County | — | — |
| Castrillo Contracting | Ronald Albert Jr Castrillo | — | (707) 479 0256 | Other | Santa Rosa · Sonoma County | — | — |
| Catalina Pools | Catalina Pools | — | (707) 953 6749 | Pool | Penngrove · Sonoma County | — | — |
| Catlin Building | Catlin Building | — | (510) 760 1081 | GC, remodel, ADU | Petaluma · Sonoma County | — | — |
| Cats 4 U INC | Clay Wallace Green | — | (707) 433 8304 | Other | Healdsburg · Sonoma County | — | — |
| Cavallo Construction | Justin Scott Cavallo | — | (707) 228 5650 | GC, remodel, ADU | Cloverdale · Sonoma County | — | — |
| Cavallo Enterprises INC DBA The Welding Shop | Scott Douglas Cavallo | — | (707) 433 5108 | Other | Healdsburg · Sonoma County | — | — |
| Cave Custom Construction | Jason Charles Cave | — | (650) 477 8512 | GC, remodel, ADU | Penngrove · Sonoma County | — | — |
| Cb Excavating | Cb Excavating | — | (707) 338 4979 | Other | Cotati · Sonoma County | — | — |
| Cb's Custom Construction | Christopher Michael Brown | — | (707) 695 8261 | GC, remodel, ADU | Fulton · Sonoma County | — | — |
| Cbk Construction & Development | Michael J Robin | — | (707) 695 8585 | GC, remodel, ADU | Petaluma · Sonoma County | — | — |
| Ccurtiselectric | Christian Daniel Curtis | — | (707) 527 2673 | Electricians | Windsor · Sonoma County | — | — |
| Cedar Fox Construction | Agustin Eduardo Mota | — | (707) 547 7573 | GC, remodel, ADU | Healdsburg · Sonoma County | — | — |
| Ceja Construction & Maintenance | Rafael Enriquez Ceja | — | (707) 494 1568 | GC, remodel, ADU | Santa Rosa · Sonoma County | — | — |
| Centerline Design/build | Centerline Design/build | — | (415) 519 4463 | GC, remodel, ADU | Sonoma · Sonoma County | — | — |
| Central Pro ' S Heating & Air INC | Matthew James Soderstrom | — | (707) 888 7363 | HVAC | Santa Rosa · Sonoma County | — | — |
| Centurion Construction Co | Martin Rodriguez Hernandez | — | (707) 974 6559 | GC, remodel, ADU | Sonoma · Sonoma County | — | — |
| Century Fencing Company INC | Mosqueda Carlos | — | (707) 327 8348 | Other | Windsor · Sonoma County | — | — |
| Ceresa Construction | Scott Brian Ceresa | — | (707) 481 8416 | GC, remodel, ADU | Penngrove · Sonoma County | — | — |
| Cervantes Landscape LLC | Oscar Fernando Cervantes Huerta | — | (707) 721 9152 | Windows, patio, painters | Petaluma · Sonoma County | — | — |
| Cervantes Landscaping | Cervantes Landscaping | — | (707) 291 7680 | Windows, patio, painters | Windsor · Sonoma County | — | — |
| Ces Plumbing INC DBA Economy Plumbing | Susan Denise Jensen | — | (707) 545 4455 | Other | Santa Rosa · Sonoma County | — | — |
| Cesar Galarza Flores | Cesar Galarza Flores | — | (707) 774 1795 | GC, remodel, ADU | Petaluma · Sonoma County | — | — |
| Cf Builders | Cassy Elizabeth Fabiani | — | (415) 779 4215 | Other roofers | Santa Rosa · Sonoma County | — | — |
| Chad Empey DBA The Glass Shop Of The North Bay | Chad Kalen Empey | — | (707) 762 1900 | GC, remodel, ADU | Petaluma · Sonoma County | — | — |
| Chalk Hill General Building | Chalk Hill General Building | — | (707) 494 8018 | GC, remodel, ADU | Healdsburg · Sonoma County | — | — |
| Champlain Builder | Champlain Builder | — | (707) 331 6236 | GC, remodel, ADU | Sebastopol · Sonoma County | — | — |
| Chandi Constructions INC | Anthony Davis Merciari | — | (925) 348 2693 | GC, remodel, ADU | Santa Rosa · Sonoma County | — | — |
| Chandler Brothers Construction INC | Tina Renea Chandler | — | (707) 332 3109 | GC, remodel, ADU | Santa Rosa · Sonoma County | — | — |
| Chandler Construction | Ross Ryan Chandler | — | (707) 548 6771 | GC, remodel, ADU | Sebastopol · Sonoma County | — | — |
| Chandler Plumbing | Chandler Plumbing | — | (707) 236 4455 | Other | Santa Rosa · Sonoma County | — | — |
| Chapla Custom Carpentry | Chapla Custom Carpentry | — | (925) 639 5214 | GC, remodel, ADU | Santa Rosa · Sonoma County | — | — |