| Sdc Built INC | Spencer Baker Dobrovolny | — | (415) 578 2886 | GC, remodel, ADU | San Anselmo · Marin County | — | — |
| Sean Goslin Woodwork | Sean Goslin | — | (415) 888 2688 | Other | San Anselmo · Marin County | — | — |
| Sean Hardiman Construction | Sean Thomas Hardiman | — | (415) 847 4925 | Other | Larkspur · Marin County | — | — |
| Sean Joseph West | Sean Joseph West | — | (415) 827 2055 | Windows, patio, painters | Novato · Marin County | — | — |
| Sean William Cook DBA Window Worx | Window Worx | — | (415) 250 1354 | Windows, patio, painters | San Rafael · Marin County | — | — |
| Seaside Construction | Matthew Joel Trethric | — | (415) 456 4191 | GC, remodel, ADU | San Rafael · Marin County | — | — |
| Segale Construction INC | Patrick David Segale | patrick@segaleconstruction.com | (415) 250 7254 | GC, remodel, ADU | San Anselmo · Marin County | — | — |
| Selvig Development INC | Rolf Stanley Jr Selvig | — | (415) 482 9226 | GC, remodel, ADU | San Anselmo · Marin County | — | — |
| Sente Electric | Marvin Mauricio Sente Collin | senteelectric23@gmail.com | (415) 531 3087 | Electricians | San Rafael · Marin County | — | — |
| Sequoia Landscape | Sequoia Landscape | — | (415) 388 5820 | Windows, patio, painters | Mill Valley · Marin County | — | — |
| Sequoia Painting INC | Domingo Manuel Alvarez | — | (415) 310 1269 | Windows, patio, painters | San Anselmo · Marin County | — | — |
| Serecsko Bldg & Remodeling | Serecsko Bldg & Remodeling | — | (415) 888 3173 | GC, remodel, ADU | Mill Valley · Marin County | — | — |
| Serguei Makarov | Serguei Makarov | — | (415) 847 5476 | Other | Novato · Marin County | — | — |
| Sexton Construction | Raymond Joseph Sexton | — | (415) 240 2707 | GC, remodel, ADU | Novato · Marin County | — | — |
| Sgs Mechanical INC | Scott Grant Sherry | — | (415) 531 4410 | HVAC | San Rafael · Marin County | — | — |
| Shady Window Coverings | Shady Window Coverings | — | (415) 595 2600 | Other | San Rafael · Marin County | — | — |
| Shamrock Compressor Service | James Anthony Malone | — | (650) 444 4770 | Other | Corte Madera · Marin County | — | — |
| Shamrock Electric | Paul John Kelly | — | (628) 310 6837 | Electricians | Sausalito · Marin County | — | — |
| Shandley Masonry | Shandley Masonry | — | (415) 407 8727 | Other | San Rafael · Marin County | — | — |
| Shapiro Plastering INC | Jack Nathan Iii Shapiro | — | (415) 382 9600 | Other | Novato · Marin County | — | — |
| Shasta Construction | Frank Anthony Cabezud | — | (530) 244 1413 | GC, remodel, ADU | San Rafael · Marin County | — | — |
| Shawn Tibbs | Shawn Tibbs | — | (415) 410 3494 | Other | Fairfax · Marin County | — | — |
| Sheppard's Tree Care | Sheppard's Tree Care | — | (415) 487 0267 | Tree | San Geronimo · Marin County | — | — |
| Shining Star Electric | Sean Kevin Mohan | — | (415) 459 4511 | Electricians | San Anselmo · Marin County | — | — |
| Shockey Enterprise | Shockey Enterprise | — | (415) 521 0771 | GC, remodel, ADU | Novato · Marin County | — | — |
| Shoshan Construction Services | Shoshan Michael | — | (415) 302 8734 | GC, remodel, ADU | Kentfield · Marin County | — | — |
| Siena Pacific INC | Michael Austin | info@sienapacific.com | (415) 730 7207 | GC, remodel, ADU | San Rafael · Marin County | — | — |
| Signor Landscape | Signor Landscape | — | (415) 305 7472 | Windows, patio, painters | San Rafael · Marin County | — | — |
| Sil E Cervantes | Sil E Cervantes | — | (415) 898 3246 | Other | Novato · Marin County | — | — |
| Silver Services | William Bernard Silver | — | (415) 741 4885 | Windows, patio, painters | Fairfax · Marin County | — | — |
| Silverhawk & Company INC | Jeffrey Harold Batt | info@silverhawkaviation.com | (415) 381 4295 | GC, remodel, ADU | Tiburon · Marin County | — | — |
| Simon Construction | Philip Louis Simon | — | (707) 291 3641 | GC, remodel, ADU | Corte Madera · Marin County | — | — |
| Singlepoint Builders | Brant Ryan Hill | bobby@spdesignbuild.com | (415) 789 7979 | GC, remodel, ADU | Mill Valley · Marin County | — | — |
| Sivar Land Construction | Diaz Demetrio Ventura | — | (415) 375 2113 | GC, remodel, ADU | Novato · Marin County | — | — |
| Sj Builders | Sj Builders | — | (415) 786 6649 | GC, remodel, ADU | Sausalito · Marin County | — | — |
| Skornicka Designs And Construction INC | Susan Catherine Skornicka | — | (415) 640 3637 | GC, remodel, ADU | Ross · Marin County | — | — |
| Slack Construction | Logan Andrew Slack | — | (707) 364 8904 | GC, remodel, ADU | San Rafael · Marin County | — | — |
| Slaughter Construction | Lee Taylor Slaughter | — | (415) 250 9517 | GC, remodel, ADU | Forest Knolls · Marin County | — | — |
| Slobodan Rosic | Slobodan Rosic | — | (415) 813 0177 | GC, remodel, ADU | Mill Valley · Marin County | — | — |
| Sm Builder | Sm Builder | — | (425) 214 3214 | GC, remodel, ADU | San Rafael · Marin County | — | — |