| Solid Step Flooring | Solid Step Flooring | — | (707) 805 3538 | Other | Fairfield · Solano County | — | — |
| Solo Pavers Expert INC | Maicon Goncalves Da Cruz | — | (925) 255 6502 | Other | Benicia · Solano County | — | — |
| Soma Builder Co | Osvaldo Saul Aispuro Gutierrez | somabuilderco@gmail.com | (707) 342 4340 | GC, remodel, ADU | Fairfield · Solano County | — | — |
| Sonny Floors | Sonny Floors | — | (925) 360 1814 | Other | Benicia · Solano County | — | — |
| Sons Of Glory Plumbing LLC | Pedro Eduardo Diaz Valdez | sonsofgloryplumbing@gmail.com | (510) 502 9590 | Other | Vallejo · Solano County | — | — |
| Sotuela's Landscaping | Sotuela's Landscaping | — | (707) 373 6257 | Windows, patio, painters | Dixon · Solano County | — | — |
| South Shore Building Services Inc. | South Shore Building Services Inc. | — | (714) 646-0130 | Windows, patio, painters | Solana Beach · Solano County | — | — |
| Soz Electric INC | Alec James Briseno | alecb@sozelectric.com | (626) 464 4376 | Electricians | Vacaville · Solano County | — | — |
| Spark & Splice Electric | Ryan Daniel Cano | — | (530) 748 9927 | Electricians | Vallejo · Solano County | — | — |
| Spec Masters Construction Services INC | Cameron Tyrone Walker | — | (707) 438 5669 | GC, remodel, ADU | Fairfield · Solano County | — | — |
| Specialized Construction | Noel Dion Davies | — | (530) 979 7616 | GC, remodel, ADU | Dixon · Solano County | — | — |
| Spiers Electric | Kenneth David Spiers | — | (916) 612 4426 | Electricians | Vacaville · Solano County | — | — |
| Spot On Remodeling & Repair | Jerry Chandler Sevey | — | (707) 628 1286 | GC, remodel, ADU | Vacaville · Solano County | — | — |
| Spradcon Builders | Brian Glen Spradling | — | (707) 374 6735 | GC, remodel, ADU | Rio Vista · Solano County | — | — |
| Spyglass Hill Construction | Catherine Denise Rehbein | — | (408) 207 6288 | GC, remodel, ADU | Vallejo · Solano County | — | — |
| Square Root Electric LLC | Noel Bautista Rodriguez | — | (707) 631 0166 | Electricians | Vacaville · Solano County | — | — |
| Src Construction INC | Peter John Van Der Veen | info@src-construction.com | (650) 814 9522 | GC, remodel, ADU | Vallejo · Solano County | — | — |
| Srs Construction Services | Vicente Rodriguez | — | (603) 324 8335 | GC, remodel, ADU | Benicia · Solano County | — | — |
| Ss Concrete Co | Cesar Castillo Del Real | — | (707) 208 5890 | Other | Fairfield · Solano County | — | — |
| Staches Plumbing | Staches Plumbing | — | (888) 887 8224 | Other | Fairfield · Solano County | — | — |
| Standfill Custom Construction | Hershell Wesley Jr Standfill | — | (707) 592 3221 | GC, remodel, ADU | Vacaville · Solano County | — | — |
| Star Quality Painting INC | Jose Enrique Gonzalez Escobar | — | (707) 640 4083 | Windows, patio, painters | Vallejo · Solano County | — | — |
| Starcare Power Wash INC | Gregory Robert Harper | info@starcarepowerwash.com | (707) 580 3665 | Other | Vacaville · Solano County | — | — |
| Static Electric LLC | John Zack Kratsas | — | (415) 699 6669 | Electricians | Fairfield · Solano County | — | — |
| Station 1 Fire Protection | Station 1 Fire Protection | — | (707) 399 1000 | Other | Fairfield · Solano County | — | — |
| Stellar Painting | Gutierrez David Leon | interested@domainmarket.com | (925) 577 3924 | Windows, patio, painters | Vallejo · Solano County | — | — |
| Stephen H Lewis | Stephen H Lewis | — | (707) 592 3295 | GC, remodel, ADU | Vacaville · Solano County | — | — |
| Steve Aguilera DBA California Hot Work | California Hot Work | — | (805) 796 7307 | Other | Benicia · Solano County | — | — |
| Steve Hanley Construction INC DBA Hanley Homes | Jeanne Pryor Hanley | — | (707) 373 6950 | GC, remodel, ADU | Fairfield · Solano County | — | — |
| Steve Smith Electric | Stephen Anthony Smith | — | (707) 249 1848 | Electricians | Rio Vista · Solano County | — | — |
| Steve Wasso Paving | Steve Wasso Paving | — | (530) 983 7201 | Other | Dixon · Solano County | — | — |
| Steve Wendling Construction | Steven Robert Wendling | — | (707) 374 6693 | GC, remodel, ADU | Rio Vista · Solano County | — | — |
| Steve Winn | Steve Winn | — | (800) 684 6970 | Electricians | Vacaville · Solano County | — | — |
| Steve's Home Repairs INC | Steven Paul Bauer | — | (916) 678 2222 | GC, remodel, ADU | Fairfield · Solano County | — | — |
| Steven's Painting | Steven's Painting | — | (707) 422 0896 | Windows, patio, painters | Fairfield · Solano County | — | — |
| Stevens Grading & Paving | Frank Joseph Jr Stevens | — | (530) 338 7738 | Other | Dixon · Solano County | — | — |
| Stover Home Painting Services | Jason Scott Stover | — | (707) 918 0118 | Windows, patio, painters | Vallejo · Solano County | — | — |
| Stream Line | Stream Line | info@stream-line.com | (925) 207 6751 | Electricians | Vallejo · Solano County | — | — |
| Streamline Controls LLC | Aaron John Fahden | customercare@streamlinecontrols.com | (925) 207 6751 | Electricians | Vallejo · Solano County | — | — |
| Streamline Landscape | Streamline Landscape | — | (707) 689 7227 | Windows, patio, painters | Vacaville · Solano County | — | — |