| Shepards Concrete Construction LLC | Tyler Michael Shepard | — | (707) 489 1429 | GC, remodel, ADU | Ukiah · Mendocino County | — | — |
| Sherosick Construction | James Michael Sherosick | — | (707) 485 0204 | GC, remodel, ADU | Redwood Valley · Mendocino County | — | — |
| Shoreline Construction | Robert Lee Jr Smith | info@shoreline-construction.com | (707) 483 8750 | GC, remodel, ADU | Gualala · Mendocino County | — | — |
| Sierra Pacific Construction | Matthew Ray Keizer | — | (707) 234 9757 | GC, remodel, ADU | Redwood Valley · Mendocino County | — | — |
| Slates Quality Construction | Jacob Aaron Slates | — | (707) 272 2591 | GC, remodel, ADU | Ukiah · Mendocino County | — | — |
| Small Projects Contracting | Larry Gregory Knowles | — | (707) 485 4168 | GC, remodel, ADU | Mendocino · Mendocino County | — | — |
| Smart Leak Protection LLC | Ian Jacob Schrager | — | (808) 870 0075 | Other | Mendocino · Mendocino County | — | — |
| Smith Brothers Construction | Mark Vincent Smith | — | (707) 743 2833 | Other | Potter Valley · Mendocino County | — | — |
| Sobieski Construction | Steven Adam Sobieski | — | (707) 357 4234 | GC, remodel, ADU | Fort Bragg · Mendocino County | — | — |
| Sonoma Sweepers INC | Jeffrey Lon Spharler | — | (707) 462 7467 | Windows, patio, painters | Ukiah · Mendocino County | — | — |
| Spangler Construction | Jason Noel Spangler | bill@spanglerconstruction.com | (707) 888 2943 | GC, remodel, ADU | Gualala · Mendocino County | — | — |
| Speedy Signs | Speedy Signs | info@speedysigns.com | (707) 462 9289 | Windows, patio, painters | Ukiah · Mendocino County | — | — |
| Spring Valley Homes INC | Barbara Anne Mitchell | — | (707) 489 1080 | GC, remodel, ADU | Willits · Mendocino County | — | — |
| Srm Construction | Skylar Ray Martin | — | (707) 391 2179 | GC, remodel, ADU | Gualala · Mendocino County | — | — |
| Steele Cat Construction | George Nicholas Steele | — | (707) 743 1502 | Other | Potter Valley · Mendocino County | — | — |
| Steve Henderson Construction | Steve Eugene Henderson | — | (707) 272 0603 | GC, remodel, ADU | Philo · Mendocino County | — | — |
| Steve Roberts Roofing | Stephen Dale Roberts | — | (707) 391 5943 | Other roofers | Ukiah · Mendocino County | — | — |
| Sticks Construction | Richard Edward Rewerts | — | (707) 245 6921 | GC, remodel, ADU | Willits · Mendocino County | — | — |
| Stocker Construction | Morgan Ignacio Stocker | — | (707) 367 8802 | GC, remodel, ADU | Ukiah · Mendocino County | — | — |
| Stone Builders Incorporated | Thomas James Stone | — | (925) 525 9726 | GC, remodel, ADU | Hopland · Mendocino County | — | — |
| Streamline Gutters | Streamline Gutters | — | (707) 354 2726 | Other | Willits · Mendocino County | — | — |
| Summit Signal INC | Daniel Michael Mihelcic | — | (707) 456 9515 | Electricians | Willits · Mendocino County | — | — |
| Sundstrom Construction INC | Donald Andrew Sundstrom | — | (707) 888 5510 | GC, remodel, ADU | Gualala · Mendocino County | — | — |
| Super Coats Painting | Super Coats Painting | — | (707) 972 5403 | Windows, patio, painters | Willits · Mendocino County | — | — |
| Superior Pump & Drilling INC | Carey Dawn Quevedo | — | (707) 964 9511 | GC, remodel, ADU | Fort Bragg · Mendocino County | — | — |
| Sweet Home Builder | Sweet Home Builder | — | (707) 485 2177 | GC, remodel, ADU | Redwood Valley · Mendocino County | — | — |
| Swithenbank Construction INC | Travis Walker Swithenbank | — | (707) 964 7460 | GC, remodel, ADU | Fort Bragg · Mendocino County | — | — |
| Syfert Electric | John L Jr Syfert | — | (707) 489 5589 | Electricians | Ukiah · Mendocino County | — | — |
| Systemic Tree Service INC | Duane Macy Sanborn | info@systemictreeservice.com | (707) 239 1867 | Tree | Redwood Valley · Mendocino County | — | — |
| Tanner Flagg Construction | Tanner Frederick Flagg-perkins | — | (925) 788 1215 | GC, remodel, ADU | Mendocino · Mendocino County | — | — |
| Tarbell Woodworks & Associates | Crescent Dean Tarbell | — | (510) 847 4685 | GC, remodel, ADU | Mendocino · Mendocino County | — | — |
| Taylor B Duryee | Taylor B Duryee | — | (707) 357 3508 | Electricians | Fort Bragg · Mendocino County | — | — |
| Taylor Drywall | Taylor Drywall | — | (707) 961 9625 | Other | Fort Bragg · Mendocino County | — | — |
| Taylor Enterprises | Jeff Scott Taylor | — | (707) 489 0267 | GC, remodel, ADU | Redwood Valley · Mendocino County | — | — |
| Taylor Made Hardwood Floors | Taylor Made Hardwood Floors | — | (707) 391 4137 | Other | Ukiah · Mendocino County | — | — |
| Taylor's Heating And Cooling | Taylor's Heating And Cooling | — | (707) 670 3828 | HVAC | Ukiah · Mendocino County | — | — |
| Telecom Services Co | Richard Patrick Thornton | — | (707) 463 2083 | Other | Ukiah · Mendocino County | — | — |
| Teo's Roofing | Castro-analco Doroteo | — | (707) 813 0722 | Other roofers | Fort Bragg · Mendocino County | — | — |
| Terra Tech Excavation | Terra Tech Excavation | — | (707) 972 4997 | Other | Ukiah · Mendocino County | — | — |
| Terry's Painting | Terry's Painting | — | (707) 357 2857 | Windows, patio, painters | Fort Bragg · Mendocino County | — | — |