| Silva's Pipeline INC | James Albert Silva | — | (510) 786 2722 | Other | Hayward · Alameda County | — | — |
| Silver Maple Construction Corp | Javier Hernandez Velasco | — | (510) 733 5930 | GC, remodel, ADU | Hayward · Alameda County | — | — |
| Silver Planet Ornamental Fabrication | Silver Planet Ornamental Fabrication | — | (510) 461 2980 | Other | Alameda · Alameda County | — | — |
| Silverado Contractors INC | Joseph Martin Capriola | — | (510) 658 9960 | GC, remodel, ADU | Emeryville · Alameda County | — | — |
| Sima Construction Corp | Frazier Angel Goopar Bustamante | — | (510) 927 0203 | GC, remodel, ADU | San Leandro · Alameda County | — | — |
| Simon Yang Construction INC | Wusheng Yang | — | (341) 345 5797 | GC, remodel, ADU | San Leandro · Alameda County | — | — |
| Simonds Construction | Eric James Simonds | — | (925) 895 4142 | GC, remodel, ADU | Livermore · Alameda County | — | — |
| Simple Consulting Corporation | Jia Liang | — | (628) 333 9083 | GC, remodel, ADU | Berkeley · Alameda County | — | — |
| Simplisafe | Simplisafe | customer-support@simplisafe.co.uk | — | Alarm and generators | Alameda · Alameda County | — | — |
| Simply Better Remodels | Allan Ronald Odell | — | (925) 209 1166 | GC, remodel, ADU | Livermore · Alameda County | — | — |
| Simply Plumbing And Rooter | Simply Plumbing And Rooter | — | (310) 493 1648 | Other | Hayward · Alameda County | — | — |
| Simply Trees | Jason Logan Beeman | — | (925) 321 2421 | Tree | Livermore · Alameda County | — | — |
| Sinaloas Drywall INC | Jose Luis Martinez Calderon | — | (415) 583 4300 | Other | Oakland · Alameda County | — | — |
| Sincere Home Installation & Construction LLC | Shu Kei Chung | — | (510) 268 1167 | GC, remodel, ADU | Oakland · Alameda County | — | — |
| Sine Metu Services Corp | Kevin Scott Jameson | — | (925) 922 6195 | GC, remodel, ADU | Livermore · Alameda County | — | — |
| Singh Air Systems | Singh Air Systems | — | (408) 705 5594 | HVAC | Hayward · Alameda County | — | — |
| Singh Electrical Us LLC | Singh Gurbakhash | — | (510) 565 8452 | Electricians | Union City · Alameda County | — | — |
| Singh Signs | Rajinder Singh Bhachu | — | (510) 573 3162 | Other | Fremont · Alameda County | — | — |
| Singha Construction INC | Rhushantha Senaka Wanigatunga | — | (415) 658 5213 | GC, remodel, ADU | Alameda · Alameda County | — | — |
| Single Flush Plumbing INC | Cabrera Diaz Benito | — | (510) 390 0784 | Other | Hayward · Alameda County | — | — |
| Singlesource INC | Kirk Dennis Schenk | — | (510) 483 4800 | Other | San Leandro · Alameda County | — | — |
| Sinh Electric Co | Sinh A Truong | — | (415) 748 0707 | Electricians | San Leandro · Alameda County | — | — |
| Sisic Painting & Decorating | Sisic Painting & Decorating | — | (510) 967 7216 | Windows, patio, painters | Hayward · Alameda County | — | — |
| Situ Construction INC | Situ Ming | — | (510) 918 1682 | GC, remodel, ADU | Castro Valley · Alameda County | — | — |
| Sixth Dimenson Pmcm INC | Karl Jerome Schultz | — | (925) 408 1593 | GC, remodel, ADU | Pleasanton · Alameda County | — | — |
| Sjn Electric LLC | Sidney John Nielsen | — | (510) 867-8700 | Electricians | San Leandro · Alameda County | — | — |
| Sk Construction INC | Aziz Sher | — | (510) 298 8403 | GC, remodel, ADU | Fremont · Alameda County | — | — |
| Skb Electrical Services | Sean Kevin Koepp-Baker | — | (925) 667 1236 | Electricians | Livermore · Alameda County | — | — |
| Skuza Interiors INC | Skuza Karol | — | (510) 362 5979 | GC, remodel, ADU | Fremont · Alameda County | — | — |
| Sky Bridge INC | Ricardo Gabrielle Quintero | — | (415) 559 0673 | Electricians | Alameda · Alameda County | — | — |
| Sky Garage Door Repair | Dvir Meshulami | dvir.meshulami@gmail.com | (925) 453 0009 | Other | Pleasanton · Alameda County | — | — |
| Skybar Construction INC | Kelli Narwani | — | (818) 804 7516 | GC, remodel, ADU | Oakland · Alameda County | — | — |
| Skyblue Heating & Air Conditioning INC | Huan Xian| Deng Huanxian Deng | — | (510) 499 2638 | HVAC | Fremont · Alameda County | — | — |
| Skyfire Construction | Todd Israel Voyageur | info@skyfireconstruction.com | (510) 325 0509 | GC, remodel, ADU | Oakland · Alameda County | — | — |
| Skyline Electric LLC | Eduard Sandulyak | interested@domainmarket.com | (510) 470 0520 | Electricians | Hayward · Alameda County | — | — |
| Skyline Tree Surgeons INC | Scott Reid Tabler | — | (408) 998 0141 | Tree | Livermore · Alameda County | — | — |
| Skyway Electric Company | Julio Cesar Maceda | — | (510) 612 4256 | Electricians | Alameda · Alameda County | — | — |
| Slade Electric | David Alan Slade | — | (925) 373 9050 | Electricians | Livermore · Alameda County | — | — |
| Slater Custom Painting | Slater Custom Painting | — | (415) 424 9282 | Windows, patio, painters | Emeryville · Alameda County | — | — |
| Slats Blinds | Slats Blinds | — | (510) 769-7528 | Windows, patio, painters | Alameda · Alameda County | — | — |