| Hudson Electric | Boston Tyler Bradfo Hudson | anapbm@gmail.com | (530) 902 2023 | Electricians | Montague · Siskiyou County | — | — |
| Ian Perry Construction | Ian Miles Perry | — | (541) 961 6826 | GC, remodel, ADU | Weed · Siskiyou County | — | — |
| Inline Fence Construction | Kenneth Michael King | inlineking@sbcglobal.net | (530) 905 0097 | Other | Yreka · Siskiyou County | — | — |
| J & J Construction & Electric INC | Jason Jacob Apodaca | — | (530) 925 0491 | Electricians | Gazelle · Siskiyou County | — | — |
| J Burn Construction | Joshua Karl Bernstein | — | (530) 643 0021 | GC, remodel, ADU | Yreka · Siskiyou County | — | — |
| J Cota Forestry | J Cota Forestry | — | (530) 459 3546 | Other | Montague · Siskiyou County | — | — |
| J G Flooring | J G Flooring | jonathan@jgflooring.com | (805) 423 2933 | Other | Weed · Siskiyou County | — | — |
| J L D Group INC | Darrel Wesley Collins | — | (530) 340 3103 | GC, remodel, ADU | Yreka · Siskiyou County | — | — |
| J M Solomito Builder | J M Solomito Builder | — | (831) 345 8140 | GC, remodel, ADU | Montague · Siskiyou County | — | — |
| J R Mathwig Builders | J R Mathwig Builders | — | (425) 512 4432 | GC, remodel, ADU | Weed · Siskiyou County | — | — |
| J S Construction | Jason David Schalow | — | (530) 339 1859 | GC, remodel, ADU | Yreka · Siskiyou County | — | — |
| J S E Courts LLC | Steve Estle Sluss | — | (808) 658 0005 | Other | Weed · Siskiyou County | — | — |
| J. Graff's Custom Floors | J. Graff's Custom Floors | — | (541) 539 1478 | Other | Bray · Siskiyou County | — | — |
| Jack Kelly Plumbing | Jack Kelly Plumbing | — | (530) 966 4345 | Other | Dunsmuir · Siskiyou County | — | — |
| Jackson Construction | Walter Jackson Phillips | contact@sansoxygen.com | (530) 918 9129 | GC, remodel, ADU | Mt Shasta · Siskiyou County | — | — |
| Jake's Construction Company | Jason Gary Gress | — | (307) 690 2440 | GC, remodel, ADU | Mt Shasta · Siskiyou County | — | — |
| James A Walton | James A Walton | — | (530) 468 2901 | GC, remodel, ADU | Greenview · Siskiyou County | — | — |
| Jardin - Complete Landscaping Service | Lisa Ann Bouchez | — | (530) 938 2106 | Windows, patio, painters | Weed · Siskiyou County | — | — |
| Jay Gregory Construction INC | Jay Thomas Gregory | — | (530) 925 4799 | GC, remodel, ADU | Weed · Siskiyou County | — | — |
| Jd's North State Building | Jd's North State Building | — | (530) 519 9021 | GC, remodel, ADU | Greenview · Siskiyou County | — | — |
| Jed Faulkner Electric | Jedidiah David Faulkner | — | (530) 598 6418 | Electricians | Fort Jones · Siskiyou County | — | — |
| Jefferson State Water LLC | Christopher Bryden Von Tickner | — | (530) 598 2362 | Other | Yreka · Siskiyou County | — | — |
| Jerome Walker Plumbing | Jerome Walker Plumbing | — | (530) 925 9239 | Other | Weed · Siskiyou County | — | — |
| Jesse Ramirez Welding INC | Jesus H Jr Ramirez | — | (530) 859 3500 | Other | Mt Shasta · Siskiyou County | — | — |
| Joe's Mid Valley Electric LLC | Joe Ray Sisk | — | (530) 905 0838 | Electricians | Montague · Siskiyou County | — | — |
| John Burrone Construction | John Allen Burrone | — | (530) 468 4336 | GC, remodel, ADU | Fort Jones · Siskiyou County | — | — |
| John Hammond Construction & Design | John Earle Hammond | — | (530) 355 8252 | GC, remodel, ADU | Montague · Siskiyou County | — | — |
| John Hopkins Electric | John Schofield Hopkins | — | (619) 261 1414 | Electricians | Tulelake · Siskiyou County | — | — |
| John L. Scott Real Estate | Siskiyou | John L. Scott Real Estate | Siskiyou | — | (530) 842-7319 | Property managers | Yreka · Siskiyou County | — | — |
| John Pauza Const | John Pauza Const | — | (831) 278 0107 | GC, remodel, ADU | Mt Shasta · Siskiyou County | — | — |
| Johnny Callahan Wood Working | Johnny Callahan Wood Working | — | (530) 301 0733 | GC, remodel, ADU | Callahan · Siskiyou County | — | — |
| Jon Purvis DBA Benson And Sons Roofing | Jonathan Wayne Purvis | — | (530) 926 4700 | Other roofers | Dunsmuir · Siskiyou County | — | — |
| Julian's Tile & Stone | Julian's Tile & Stone | — | (530) 261 1274 | Other | Mt Shasta · Siskiyou County | — | — |
| K W L Builders | K W L Builders | — | (530) 598 7078 | GC, remodel, ADU | Yreka · Siskiyou County | — | — |
| Katstruction | Keith Alan Taylor | — | (530) 598 5556 | GC, remodel, ADU | Etna · Siskiyou County | — | — |
| Keen Built LLC | Jeremy Dale Keen | — | (530) 925 2525 | GC, remodel, ADU | Weed · Siskiyou County | — | — |
| Kegg's Kreation | Kegg's Kreation | — | (530) 842 2360 | GC, remodel, ADU | Yreka · Siskiyou County | — | — |
| Ken Mills Construction | Kenneth William Mills | — | (707) 372 5125 | GC, remodel, ADU | Mc Cloud · Siskiyou County | — | — |
| Kenny Construction | Frank Jerard Kenny | — | (415) 349 9333 | GC, remodel, ADU | Yreka · Siskiyou County | — | — |
| Kenny's Lock Shop | Kenny's Lock Shop | — | (530) 643 3765 | Other | Montague · Siskiyou County | — | — |