| Silver And Black Construction | Edward James Schwab | — | (415) 971 0485 | GC, remodel, ADU | Santa Rosa · Sonoma County | — | — |
| Silver Creek Tile & Stone | Leonardo Pennacchio | — | (707) 543 5955 | Other | Rohnert Park · Sonoma County | — | — |
| Silver Lining Construction INC | James Francis Dietz | — | (707) 235 3585 | GC, remodel, ADU | Santa Rosa · Sonoma County | — | — |
| Silverado Cabinet & Mill Work INC | Valentin Armando Garcia Tovar | — | (707) 235 2957 | Other | Santa Rosa · Sonoma County | — | — |
| Silveria Electric INC | Steve Anthony Silveria | — | (707) 824 1499 | Electricians | Sebastopol · Sonoma County | — | — |
| Simeone Plumbing INC | Domenic Stuart Simeone | service@simeoneplumbing.com | (707) 836 1860 | Other | Santa Rosa · Sonoma County | — | — |
| Simon & Sons Construction LLC | William Alexander Simon | — | (707) 280 7697 | GC, remodel, ADU | Penngrove · Sonoma County | — | — |
| Simon Builders | Simon Builders | — | (707) 364 0714 | GC, remodel, ADU | Petaluma · Sonoma County | — | — |
| Simpson Builders INC | Conrad Scot Simpson | mark@simpsonbuilders.com | (808) 639 9836 | GC, remodel, ADU | Glen Ellen · Sonoma County | — | — |
| Simpson Sheet Metal INC | Barbara Lynn| Richardson Barbara Lynn Simpson | — | (707) 576 1500 | HVAC | Santa Rosa · Sonoma County | — | — |
| Sir Grout Santa Rosa | Moises Alvarez | — | (707) 799 9578 | Other | Windsor · Sonoma County | — | — |
| Siri Electric | Dustin Merrill Siri | sharon@sirielectric.com | (707) 290 5868 | Electricians | Windsor · Sonoma County | — | — |
| Sisson Jessie | Sisson Jessie | — | (707) 331 2330 | GC, remodel, ADU | Rohnert Park · Sonoma County | — | — |
| Sk Unlimited Construction INC | Kamen Georgiev Georgiev | — | (707) 800 5313 | GC, remodel, ADU | Santa Rosa · Sonoma County | — | — |
| Skaggs Construction Company | Stephen Warren Skaggs | — | (707) 529 5950 | GC, remodel, ADU | Santa Rosa · Sonoma County | — | — |
| Skillman Construction And Design LLC | Gerald Allen Bunch | — | (707) 636 4078 | GC, remodel, ADU | Santa Rosa · Sonoma County | — | — |
| Skillz Construction INC | Mendoza Omar Alvarez | — | (707) 800 2961 | GC, remodel, ADU | Windsor · Sonoma County | — | — |
| Skip Blunt | Skip Blunt | — | (509) 389 0666 | GC, remodel, ADU | Cazadero · Sonoma County | — | — |
| Sky Builders INC | Jody Sky Matula | — | (707) 529 3660 | Electricians | Santa Rosa · Sonoma County | — | — |
| Sky Crew Construction | Sebastian Adam Collet | — | (707) 548 7113 | Other | Sebastopol · Sonoma County | — | — |
| Skyline Seamless Gutters INC | Joel Antonio Hernandez Menjivar | skylinegutter25@gmail.com | (707) 892 3877 | Other | Rohnert Park · Sonoma County | — | — |
| Skyview Tree Experts INC | Daniel Brill Dunn | — | (707) 890 1215 | Windows, patio, painters | Santa Rosa · Sonoma County | — | — |
| Slater's Professional Tree Care | Slater's Professional Tree Care | — | (707) 892 1471 | Tree | Santa Rosa · Sonoma County | — | — |
| Slembrouck/many Corporation | Chad David Price | — | (707) 778 0170 | Electricians | Petaluma · Sonoma County | — | — |
| Sloan & Son Painting | Sloan & Son Painting | — | (707) 765 1617 | Windows, patio, painters | Petaluma · Sonoma County | — | — |
| Sm Builder | Sm Builder | — | (707) 239 4021 | GC, remodel, ADU | Windsor · Sonoma County | — | — |
| Small Jobs Plumbing INC | Zachary Don Bautista | — | (707) 766 0887 | Other | Rohnert Park · Sonoma County | — | — |
| Smart Roofing Systems INC | Steven Michael Gubera | — | (707) 495 4036 | Other roofers | Santa Rosa · Sonoma County | — | — |
| Smith Builders Company | Nicholas Gregory Smith | — | (707) 318 5064 | GC, remodel, ADU | Santa Rosa · Sonoma County | — | — |
| Smook Electric | Patrick Rudolph Smook | — | (707) 494 3928 | Electricians | Cloverdale · Sonoma County | — | — |
| Smooth Style Concrete Construction INC | Barragan Hector | — | (707) 837 5238 | Other | Windsor · Sonoma County | — | — |
| Snyder Construction INC | Thomas Francis Snyder | — | (707) 829 3060 | GC, remodel, ADU | Windsor · Sonoma County | — | — |
| So Co Painting INC | Lopez Yonan Arango | — | (707) 975 5815 | Windows, patio, painters | Rohnert Park · Sonoma County | — | — |
| Soberg Custom Builds | Soberg Custom Builds | — | (602) 810 3214 | GC, remodel, ADU | Cotati · Sonoma County | — | — |
| Soco Electric INC | Alberto Evan Valencia | jon.fitzgerald@socoelectric.com | (707) 490 7306 | Electricians | Santa Rosa · Sonoma County | — | — |
| Soco General Construction | David Alexander Miramontez | — | (707) 543 6355 | GC, remodel, ADU | Santa Rosa · Sonoma County | — | — |
| Soco Painting | Soco Painting | — | (707) 772 9531 | Windows, patio, painters | Santa Rosa · Sonoma County | — | — |
| Soiland Co INC | Mark Douglas Soiland | firstname@soiland.com | (707) 795 1775 | Other | Cotati · Sonoma County | — | — |
| Soiland Grading LLC | Kevin Allen Soiland | — | (707) 799 1175 | Other | Santa Rosa · Sonoma County | — | — |
| Sol Landscapes INC | Lena Salvaterese Furlong | — | (707) 981 7909 | Windows, patio, painters | Petaluma · Sonoma County | — | — |