| Spyrka Electric | Spyrka Electric | — | (707) 523-3155 | Electricians | Santa Rosa · Napa County | — | — |
| Square Landscaping | Hien Nguyen | — | (707) 567 9797 | Windows, patio, painters | American Canyon · Napa County | — | — |
| St Helena Construction INC | Ricardo David Caballero Flores | ricardo@sthelenaconstruction.com | (707) 963 8058 | GC, remodel, ADU | St Helena · Napa County | — | — |
| St Helena Development | St Helena Development | — | (707) 319 2624 | GC, remodel, ADU | St Helena · Napa County | — | — |
| St Helena Hardwood Floors LLC | James Thomas Reilley | sthelenahardwoodfloors@gmail.com | (707) 478 2987 | Other | St Helena · Napa County | — | — |
| St Helena Lighting & Design | St Helena Lighting & Design | — | (707) 322 1512 | Electricians | St Helena · Napa County | — | — |
| St Helena Plumbing | St Helena Plumbing | sainthelenaplumbing@gmail.com | (707) 230 0856 | Other | Angwin · Napa County | — | — |
| Stadelhofer Construction INC | Richard Joseph Stadelhofer | — | (707) 942 4298 | Other | Calistoga · Napa County | — | — |
| Stagner Construction INC | Michael David| Stagner Mike David Stagner | — | (707) 732 6111 | GC, remodel, ADU | Napa · Napa County | — | — |
| Standar Napa Roofing | Standar Napa Roofing | — | (209) 608-8808 | Other roofers | Napa · Napa County | — | — |
| Stephen Carter | Stephen Carter | — | (707) 226 5106 | Other | Napa · Napa County | — | — |
| Steve Ball General Contractor | Steve Ball General Contractor | — | (707) 812 4258 | GC, remodel, ADU | Napa · Napa County | — | — |
| Steve Silva Plumbing INC | Stephen Thomas Silva | — | (707) 383-6782 | GC, remodel, ADU | Napa · Napa County | — | — |
| Steve's Heating & Cooling | Steve's Heating & Cooling | — | (707) 252 4328 | HVAC | Napa · Napa County | — | — |
| Sticks - N - Stones Construction | Michael Dennis Rinker | — | (707) 226 5824 | GC, remodel, ADU | Napa · Napa County | — | — |
| Stockhome Construction LLC | Ryan Kevin Joyce | — | (415) 828 7238 | GC, remodel, ADU | Napa · Napa County | — | — |
| Stone & Tile Creations | Stone & Tile Creations | — | (707) 815 3227 | Other | Napa · Napa County | — | — |
| Straughn Communications INC | Grace Alane Young | — | (707) 255 1448 | Other | Napa · Napa County | — | — |
| Stroke Of Brilliance Painting | Stroke Of Brilliance Painting | — | (707) 363 0205 | Windows, patio, painters | Napa · Napa County | — | — |
| Stubbs Roofing Incorporated | Patricia Jean Stubbs | stubbsroofingincorporated@gmail.com | (707) 255 6479 | Other roofers | Napa · Napa County | — | — |
| Sullivan Construction And Home Repair INC | David Robert Sullivan | — | (707) 337 0478 | GC, remodel, ADU | Napa · Napa County | — | — |
| Sun Heating & Air Conditioning | Sun Heating & Air Conditioning | — | (707) 226 3852 | HVAC | Napa · Napa County | — | — |
| Sunrise Construction | Orin Robert Wakefield | — | (707) 426 9596 | GC, remodel, ADU | Napa · Napa County | — | — |
| Sunshine Remodeling INC | Kulwant Singh Bains | — | (415) 279 1133 | GC, remodel, ADU | American Canyon · Napa County | — | — |
| Sunshine Roofing | Julio Abriel Reyes | — | (707) 712 0726 | Other roofers | American Canyon · Napa County | — | — |
| Sunsweet Cabinetry | Sunsweet Cabinetry | — | (707) 252 9900 | Other | Napa · Napa County | — | — |
| Superior Builder | Superior Builder | — | (707) 230 8557 | GC, remodel, ADU | Napa · Napa County | — | — |
| Superior Equipment Company INC | Kathleen Ann Pagendarm | — | (707) 256 3600 | Other | Napa · Napa County | — | — |
| Supremeco Painting | Jesus Michel Arroyo Cirigo | supremecopainting@gmail.com | (707) 661 3124 | Windows, patio, painters | Calistoga · Napa County | — | — |
| Surface Masters INC | Guy Lee Williams | — | (707) 257 2711 | Other | Napa · Napa County | — | — |
| Surrounds Building Works | Surrounds Building Works | — | (707) 478 0873 | GC, remodel, ADU | Calistoga · Napa County | — | — |
| Swanson's Painting | Swanson's Painting | — | (707) 333 5635 | Windows, patio, painters | Napa · Napa County | — | — |
| T & O Masonry INC | Kenneth Wayne Taylor | — | (707) 963 2582 | Other | St Helena · Napa County | — | — |
| T Brown Painting | T Brown Painting | — | (707) 287 3578 | Windows, patio, painters | Napa · Napa County | — | — |
| T J Olson | T J Olson | — | (707) 307 8850 | Other | American Canyon · Napa County | — | — |
| T N K Construction Company | Timothy Arthur Conner | — | (707) 337 9198 | GC, remodel, ADU | Napa · Napa County | — | — |
| Ta & M Drywall INC | Moises Urbina-De-Rosas | — | (925) 584 9199 | Other | Napa · Napa County | — | — |
| Tamayo General Construction LLC | Ruben Tamayo | — | (707) 699 2089 | GC, remodel, ADU | Napa · Napa County | — | — |
| Taylor - Bailey INC | Robert Clark Covey | — | (707) 968 5752 | Other | St Helena · Napa County | — | — |
| Taylor Drywall | Taylor Drywall | — | (707) 252 3040 | Other | Napa · Napa County | — | — |