| Rorabaugh Earthmoving | Rorabaugh Earthmoving | — | (707) 485 2692 | Other | Hopland · Mendocino County | — | — |
| Roscoe Construction | Branden Scott Roscoe | — | (707) 409 4366 | GC, remodel, ADU | Fort Bragg · Mendocino County | — | — |
| Rose Engineering | Gary Eugene Rose | — | (707) 813 7144 | Other | Mendocino · Mendocino County | — | — |
| Rosenthal Tree Service | Scottie Joe Rosenthal | — | (707) 489 7315 | Tree | Leggett · Mendocino County | — | — |
| Ross Mayfield Iii | Ross Mayfield Iii | — | (707) 485 4320 | Other | Redwood Valley · Mendocino County | — | — |
| Rosskopf Engineering | Rosskopf Engineering | — | (415) 515 9432 | Other | Caspar · Mendocino County | — | — |
| Round Tree Glass INC | Thomas James Rountree | — | (707) 459 6163 | Windows, patio, painters | Willits · Mendocino County | — | — |
| Rouse Masonry INC | Thaddeaus Robert Rouse | — | (707) 485 8726 | Other | Ukiah · Mendocino County | — | — |
| Rowan Construction | Port Joseph Rowan | — | (707) 964 4511 | Other | Fort Bragg · Mendocino County | — | — |
| Ruff And Associates INC | Richard Paul Ruff | — | (707) 472 0525 | GC, remodel, ADU | Hopland · Mendocino County | — | — |
| Rugg's Construction Service | Steven Webster Rugg | — | (707) 972 0500 | GC, remodel, ADU | Redwood Valley · Mendocino County | — | — |
| Rural Communities Construction LLC | Ryan Karl Larue | — | (707) 463 1975 | GC, remodel, ADU | Ukiah · Mendocino County | — | — |
| Russian River Builders | Jungan Lee Stewart | — | (707) 367 2550 | GC, remodel, ADU | Willits · Mendocino County | — | — |
| S C Excavating INC | Samuel Molyneaux Cookson | — | (707) 354 4492 | Other | Redwood Valley · Mendocino County | — | — |
| S E A Construction | Steven Eric Anderson | — | (707) 489 6606 | GC, remodel, ADU | Ukiah · Mendocino County | — | — |
| S G Huber Equipment Rental | S G Huber Equipment Rental | — | (707) 292 4902 | Other | Albion · Mendocino County | — | — |
| Sack Concrete Construction | Robert Donald Sack | — | (707) 462 0575 | GC, remodel, ADU | Ukiah · Mendocino County | — | — |
| Sagehorn Builder INC | Jedidiah Owen Sagehorn | — | (707) 472 1484 | GC, remodel, ADU | Talmage · Mendocino County | — | — |
| Saldana Power | Saldana Power | — | (707) 813 9032 | Electricians | Fort Bragg · Mendocino County | — | — |
| Sam Halstad Plumbing | Sam Halstad Plumbing | — | (707) 391 5615 | Other | Ukiah · Mendocino County | — | — |
| Sam Rangel Construction LLC | Samuel Robert Rangel | — | (707) 889 3903 | GC, remodel, ADU | Gualala · Mendocino County | — | — |
| Samuel Parsons Contracting INC | Samuel Taylor Parsons | — | (707) 684 0098 | GC, remodel, ADU | Gualala · Mendocino County | — | — |
| San Diego Grab Bars INC | Gabriel Minoru Beddoes | dave@sandiegograbbars.com | (619) 840 7844 | Other | Fort Bragg · Mendocino County | — | — |
| Sangiacomo Landscape | Sangiacomo Landscape | — | (707) 468 0747 | Windows, patio, painters | Ukiah · Mendocino County | — | — |
| Santacruz Construction | Santacruz Camarena Gerardo | — | (707) 262 2327 | GC, remodel, ADU | Ukiah · Mendocino County | — | — |
| Satterwhite Excavating | Satterwhite Excavating | — | (707) 621 2388 | Other | Redwood Valley · Mendocino County | — | — |
| Saul Estrada Painting Company | Estrada Resendiz Saul | — | (707) 755 1618 | Windows, patio, painters | Gualala · Mendocino County | — | — |
| Scanlon Contracting | Joseph Kevin Scanlon | — | (707) 367 3555 | GC, remodel, ADU | Fort Bragg · Mendocino County | — | — |
| Schaap Excavating | Schaap Excavating | — | (707) 479 5670 | Other | Gualala · Mendocino County | — | — |
| Schluter Construction | Ben Lyle Schluter | — | (707) 373 1501 | GC, remodel, ADU | Ukiah · Mendocino County | — | — |
| Scott B Anderson | Scott B Anderson | — | (707) 477 0570 | GC, remodel, ADU | Mendocino · Mendocino County | — | — |
| Scott Duval Const | Scott Duval Const | — | (707) 964 6193 | Other | Fort Bragg · Mendocino County | — | — |
| Scott Kile Construction | Glenn Scott Kile | — | (707) 513 7504 | GC, remodel, ADU | Potter Valley · Mendocino County | — | — |
| Scottish Stained Glass | Scottish Stained Glass | contact@scottishstainedglass.com | (866) 846-5758 | Windows, patio, painters | Mendocino · Mendocino County | — | — |
| Scotty Gingell | Scotty Gingell | — | (707) 367 4072 | Electricians | Fort Bragg · Mendocino County | — | — |
| Scramaglia & Hayes Construction INC | William James Jr Hayes | — | (707) 964 0300 | Electricians | Fort Bragg · Mendocino County | — | — |
| Seaside Electric | Jason Richard Friscia | bridget@seaside-electric.com | (707) 409 4691 | Electricians | Fort Bragg · Mendocino County | — | — |
| Seefeldt Construction | Seefeldt Abers | — | (707) 322 8858 | GC, remodel, ADU | Gualala · Mendocino County | — | — |
| Seefeldt INC | Seefeldt Emani | — | (707) 884 1839 | Tree | Gualala · Mendocino County | — | — |
| Selzer Realty INC | Richard Paul Selzer | — | (707) 468 0411 | GC, remodel, ADU | Ukiah · Mendocino County | — | — |