| Siskiyou Plumbing & Electrical Service INC | Emily Ann Vincent | — | (530) 842 4585 | Electricians | Yreka · Siskiyou County | — | — |
| Siskiyou Premier Realty | Siskiyou Premier Realty | — | (530) 408-3066 | Property managers | Weed · Siskiyou County | — | — |
| Siskiyou Realty Group Inc. | Siskiyou Realty Group Inc. | lemos2sell@gmail.com | (530) 841-7174 | Property managers | Yreka · Siskiyou County | — | — |
| Siskiyou Rentals | Siskiyou Rentals | — | (530) 572-5009 | Property managers | Yreka · Siskiyou County | — | — |
| Siskiyou Technical Services | John Leslie Mcgonigal | — | (530) 598 2388 | Other | Etna · Siskiyou County | — | — |
| Siskiyou Trees | Dennis Edward Lange | — | (530) 905 0855 | Windows, patio, painters | Montague · Siskiyou County | — | — |
| Siskiyou Valley Apartments | Siskiyou Valley Apartments | — | (530) 572-1662 | Property managers | Yreka · Siskiyou County | — | — |
| Siskiyou Window & Door | Siskiyou Window & Door | noah@siskiyouwindow.com | (541) 810-1144 | Windows, patio, painters | Yreka · Siskiyou County | — | — |
| Siskiyou-shasta Tree Pro LLC | Daniel John Link | — | (530) 859 3404 | Tree | Mc Cloud · Siskiyou County | — | — |
| Sky Smart Security LLC | Sky Smart Security LLC | — | (760) 335-4999 | Alarm and generators | El Centro · Siskiyou County | — | — |
| Smokey Dowling Construction | Paul Collord Kenn Dowling | — | (530) 598 0026 | GC, remodel, ADU | Etna · Siskiyou County | — | — |
| St Pierre Excavation | Cache Maxwell St Pierre | — | (208) 369 3812 | Other | Weed · Siskiyou County | — | — |
| Stearns Finish Carpentry | Stearns Finish Carpentry | — | (707) 951 3796 | Other | Somesbar · Siskiyou County | — | — |
| Stensether Painting | Stensether Painting | — | (530) 340 4507 | Windows, patio, painters | Yreka · Siskiyou County | — | — |
| Stephen Roger Benham | Stephen Roger Benham | — | (530) 488 9170 | Electricians | Mc Cloud · Siskiyou County | — | — |
| Steven A Lindborg | Steven A Lindborg | — | (925) 335 2289 | Other | Happy Camp · Siskiyou County | — | — |
| Steven Carl Kissler | Steven Carl Kissler | — | (530) 340 5084 | Other | Weed · Siskiyou County | — | — |
| Stone Heating & Air | Stone Heating & Air | office@stoneheatair.com | (541) 855-5521 | HVAC | Yreka · Siskiyou County | — | — |
| Stratton Construction | Thomas James Stratton | — | (530) 925 6533 | GC, remodel, ADU | Yreka · Siskiyou County | — | — |
| Swan Painting | Swan Painting | — | (530) 261 1333 | Windows, patio, painters | Weed · Siskiyou County | — | — |
| Swenson Excavation | Swenson Excavation | — | (530) 859 0305 | Other | Mt Shasta · Siskiyou County | — | — |
| Tagatz Painting Co | Thomas Edward Tagatz | — | (530) 351 1645 | Windows, patio, painters | Mt Shasta · Siskiyou County | — | — |
| Tari Lee And Paul Wright Interiors Drywall | Paul Jimmie Wright | — | (530) 351 3322 | Other | Etna · Siskiyou County | — | — |
| Ten Bear Builders | Ten Bear Builders | — | (530) 514 7923 | GC, remodel, ADU | Somesbar · Siskiyou County | — | — |
| Terry F Fraser | Terry F Fraser | — | (530) 598 1189 | GC, remodel, ADU | Yreka · Siskiyou County | — | — |
| The Hawk Plumbing Services | Vance Michael Hawk | — | (530) 340 9048 | Other | Etna · Siskiyou County | — | — |
| The Local Painting Company | Christian Daniel Bangert | — | (530) 308 7686 | Windows, patio, painters | Mc Cloud · Siskiyou County | — | — |
| Thomas Electric | Jeffery Scott Thomas | — | (530) 340 0180 | Electricians | Yreka · Siskiyou County | — | — |
| Thomas Henry | Thomas Henry | — | (530) 340 1841 | GC, remodel, ADU | Yreka · Siskiyou County | — | — |
| Tim Louie Construction | Timothy Patrick Louie | — | (530) 598 0235 | Other | Montague · Siskiyou County | — | — |
| Timber Gulch Construction INC | Bret Justus Ritter | info@timbergulchconstruction.com | (530) 926 9864 | GC, remodel, ADU | Mt Shasta · Siskiyou County | — | — |
| Timberworks | Harold John Knight | — | (530) 926 4093 | GC, remodel, ADU | Mt Shasta · Siskiyou County | — | — |
| Tom Ferrel | Tom Ferrel | — | (530) 926 4752 | GC, remodel, ADU | Mt Shasta · Siskiyou County | — | — |
| Tom L Clarkson | Tom L Clarkson | — | (530) 643 3248 | GC, remodel, ADU | Mount Shasta · Siskiyou County | — | — |
| Tom Mc Cullough | Tom Mc Cullough | — | (530) 351 8183 | GC, remodel, ADU | Yreka · Siskiyou County | — | — |
| Tom Russ Construction | Thomas Anthony Russ | — | (530) 356 6160 | GC, remodel, ADU | Mt Shasta · Siskiyou County | — | — |
| Tonozzi Built | Tonozzi Built | — | (530) 768 0077 | GC, remodel, ADU | Weed · Siskiyou County | — | — |
| Tribull Construction | Chris Oran Smith | — | (530) 238 5823 | GC, remodel, ADU | Yreka · Siskiyou County | — | — |
| Trooien Construction | Thomas William Trooien | — | (530) 859 2928 | GC, remodel, ADU | Mc Cloud · Siskiyou County | — | — |
| Trouette Construction | Justin Paul Trouette | — | (707) 484 1266 | GC, remodel, ADU | Weed · Siskiyou County | — | — |