| Sonoma Stone Tile | Hernandez David Llamas | — | (707) 235 3549 | Other | Sonoma · Sonoma County | — | — |
| Sonoma Strong Builder | Sonoma Strong Builder | — | (707) 529 8524 | GC, remodel, ADU | Cloverdale · Sonoma County | — | — |
| Sonoma Structural | Sonoma Structural | — | (707) 623 8680 | GC, remodel, ADU | Santa Rosa · Sonoma County | — | — |
| Sonoma Sun Electric INC | Andrew Thomas Reynolds | — | (707) 684 0024 | Electricians | Santa Rosa · Sonoma County | — | — |
| Sonoma Tile Works Incorporated | Michael James Szykowny | — | (707) 938 5559 | Other | Sonoma · Sonoma County | — | — |
| Sonoma Tree Service | Sonoma Tree Service | — | (415) 310-7411 | Tree | Sonoma · Sonoma County | — | — |
| Sonoma Tree Service Pro | Sonoma Tree Service Pro | info@sonomatreeservicepro.com | — | Tree | Sonoma · Sonoma County | — | — |
| Sonoma Tree Surgeon | Sonoma Tree Surgeon | — | (707) 235 3859 | Other | Sebastopol · Sonoma County | — | — |
| Sonoma United Electric INC | Michael Andrew Eggers | info@sonomaunitedelectric.com | (707) 321 6422 | Electricians | Santa Rosa · Sonoma County | — | — |
| Sonoma Valley Builders | Sonoma Valley Builders | — | (707) 529 0624 | GC, remodel, ADU | Santa Rosa · Sonoma County | — | — |
| Sonoma Valley Landscape | Sonoma Valley Landscape | — | (707) 217 9336 | Windows, patio, painters | Kenwood · Sonoma County | — | — |
| Sonoma Valley Painting | Sonoma Valley Painting | — | (707) 363 4994 | Windows, patio, painters | Sonoma · Sonoma County | — | — |
| Sonoma Valley Pest Control Inc. | Sonoma Valley Pest Control Inc. | tami.svpc@gmail.com | (707) 996-0202 | Pest, tile roofs | Sonoma · Sonoma County | — | — |
| Sonoma Valley Pool & Spa Service | Saul Jonathan Rozema | — | (707) 996 2082 | Pool | Sonoma · Sonoma County | — | — |
| Sonoma Valley Tree Service | Marc Edward Foley | — | (707) 227 9282 | Tree | Sonoma · Sonoma County | — | — |
| Sonoma Vintage Enterprises INC | Jackson William Alcayaga | — | (707) 775 1000 | GC, remodel, ADU | Sonoma · Sonoma County | — | — |
| Sonoma Water Services INC | James Anthony Pagliaro | — | (707) 974 8082 | Other | Santa Rosa · Sonoma County | — | — |
| Sonomarin Pool Service | Vincent Ronald Herrera | — | (707) 280 8090 | Pool | Santa Rosa · Sonoma County | — | — |
| Soper Tile & Stone | Soper Tile & Stone | — | (707) 540 5282 | Other | Penngrove · Sonoma County | — | — |
| Soriano's Custom Builder INC | Cristobal David Soriano Ramirez | — | (415) 532 9105 | GC, remodel, ADU | Santa Rosa · Sonoma County | — | — |
| Soriano's Lathing & Plastering INC | Navarro Alain Soriano | — | (707) 791 9309 | Other | Forestville · Sonoma County | — | — |
| Sotero Concrete Construction | Gonzalez Farias Sotero | — | (707) 774 5716 | Other | Petaluma · Sonoma County | — | — |
| Soto Construction | Soto Lugo Ismael | — | (707) 322 6844 | Other roofers | Santa Rosa · Sonoma County | — | — |
| Soule Building Systems INC | William Warren Ringstad | — | (707) 793 9277 | GC, remodel, ADU | Windsor · Sonoma County | — | — |
| Soulie Construction | Christian Arnett Soulie | — | (707) 228 7065 | GC, remodel, ADU | Santa Rosa · Sonoma County | — | — |
| Sound Construction | Robert Camusus White | contact@sound-construction.com | (415) 308 4017 | GC, remodel, ADU | Camp Meeker · Sonoma County | — | — |
| Sound Management Group Limited Liability Company | Keith Patrick Barkman | — | (908) 295 9027 | Other | Rohnert Park · Sonoma County | — | — |
| Sousa Engineering | Sousa Engineering | — | (707) 349 5554 | Other | Windsor · Sonoma County | — | — |
| Southern Cross Construction | Daniel Paul Whooley | — | (415) 350 6531 | GC, remodel, ADU | Petaluma · Sonoma County | — | — |
| Southtech Construction | Roberto Eliseo Felipe | — | (707) 721 9297 | GC, remodel, ADU | Sonoma · Sonoma County | — | — |
| Souza General Engineering | Souza General Engineering | josh@souzageneralengineering.com | (707) 529 1674 | Other | Petaluma · Sonoma County | — | — |
| Spa Dad And Son | Sam Alex Zifferblatt | — | (707) 480 0950 | Pool | Guerneville · Sonoma County | — | — |
| Spaletta General Engineering | Spaletta General Engineering | — | (707) 303 6484 | Other | Petaluma · Sonoma County | — | — |
| Sparrow Construction | Brian Christopher Fitzpatrick | — | (707) 548 7030 | GC, remodel, ADU | Kenwood · Sonoma County | — | — |
| Spaulding Metals | Spaulding Metals | spauldingmetals@gmail.com | (707) 849 5481 | Other | Petaluma · Sonoma County | — | — |
| Spears Painting | Spears Painting | — | (707) 591 5141 | Windows, patio, painters | Windsor · Sonoma County | — | — |
| Specialized Storage Systems INC | Angelo Paul Longhetto | — | (925) 455 4780 | Other | Rohnert Park · Sonoma County | — | — |
| Specialty Improvements Unlimited | Specialty Improvements Unlimited | eric@siucnd.com | (707) 328 3555 | GC, remodel, ADU | Forestville · Sonoma County | — | — |
| Spencer Cabinet And Millwork | Spencer Cabinet And Millwork | — | (707) 322 8121 | Other | Penngrove · Sonoma County | — | — |
| Spiffy's | Jose Jesus Rodriquez | — | (707) 935 1831 | Other | Sonoma · Sonoma County | — | — |