| Innovative Landscapes | Innovative Landscapes | — | (707) 502 8562 | Windows, patio, painters | Eureka · Humboldt County | — | — |
| Inter-county Flooring | Inter-county Flooring | — | (707) 444 2158 | Other | Eureka · Humboldt County | — | — |
| Island State Construction | Ewan Horace Mclean | — | (707) 362 9093 | GC, remodel, ADU | Eureka · Humboldt County | — | — |
| J & G Lawn & Garden | Jeremy Edward Sisson | — | (707) 725 2731 | Windows, patio, painters | Fortuna · Humboldt County | — | — |
| J & M Builders | Matthew Wyatt Lang | — | (707) 273 8658 | GC, remodel, ADU | Eureka · Humboldt County | — | — |
| J Bailey Electrical | Jacob David Bailey | — | (707) 601 2533 | Electricians | Willow Creek · Humboldt County | — | — |
| J C Adams Construction | John Colby Adams | — | (707) 616 3277 | GC, remodel, ADU | Eureka · Humboldt County | — | — |
| J C Wilson Construction | Jared Cole Wilson | — | (707) 496 1193 | GC, remodel, ADU | Rio Dell · Humboldt County | — | — |
| J Kidd Construction INC | Kidd Jason | contact@jkiddconstruction.com | (707) 498 3351 | GC, remodel, ADU | Bayside · Humboldt County | — | — |
| J L Campbell Construction | John Lee Campbell | — | (707) 672 5544 | GC, remodel, ADU | Mc Kinleyville · Humboldt County | — | — |
| J L F Construction INC | Pedro Narcisameto Furtado | — | (707) 839 0137 | GC, remodel, ADU | Mc Kinleyville · Humboldt County | — | — |
| J L G Construction | Justin Liam Gaffney | — | (707) 296 8807 | GC, remodel, ADU | Trinidad · Humboldt County | — | — |
| J M H Real Estate & Construction Services INC | Jeffrey Mark Hildreth | — | (707) 616 8843 | GC, remodel, ADU | Whitethorn · Humboldt County | — | — |
| J M Hardcastle Fencing | J M Hardcastle Fencing | — | (707) 444 2377 | Other | Arcata · Humboldt County | — | — |
| J P Construction | Jeffrey Keel Porter | — | (714) 329 4740 | GC, remodel, ADU | Redway · Humboldt County | — | — |
| J P Construction | Preciado Jesse | — | (707) 834 2940 | GC, remodel, ADU | Eureka · Humboldt County | — | — |
| J R H Construction | Joshua Robert Hiscox | — | (707) 498 1605 | GC, remodel, ADU | Eureka · Humboldt County | — | — |
| J R Stephens Company | Jim Ray Stephens | — | (707) 825 0100 | Other | Arcata · Humboldt County | — | — |
| J Roley Construction | John Ramsey Roley | — | (707) 498 7774 | GC, remodel, ADU | Mc Kinleyville · Humboldt County | — | — |
| J Stark Construction | Josha Ocean Stark | — | (707) 813 0029 | GC, remodel, ADU | Blue Lake · Humboldt County | — | — |
| J T A Construction | Jon Tracy Adams | — | (707) 499 6190 | GC, remodel, ADU | Mc Kinleyville · Humboldt County | — | — |
| J V Floors | J V Floors | — | (707) 296 6949 | Other | Fortuna · Humboldt County | — | — |
| J W Construction | Jon Charles Williams | — | (707) 498 3427 | GC, remodel, ADU | Eureka · Humboldt County | — | — |
| Jack Biondini Construction INC | Jack Joseph Biondini | — | (707) 499 1705 | GC, remodel, ADU | Hoopa · Humboldt County | — | — |
| Jack Lamb Plumbing | Jack Lamb Plumbing | — | (707) 601 9039 | Other | Eureka · Humboldt County | — | — |
| Jackson Construction | Erik Allen Jackson | contact@sansoxygen.com | (707) 599 2608 | GC, remodel, ADU | Mc Kinleyville · Humboldt County | — | — |
| Jacob Kadle Construction | Jacob Walter Kadle | — | (707) 498 1991 | GC, remodel, ADU | Mc Kinleyville · Humboldt County | — | — |
| Jacobs Building | Jacobs Building | — | (707) 496 4391 | GC, remodel, ADU | Mc Kinleyville · Humboldt County | — | — |
| James Bernard Parker | James Bernard Parker | — | (707) 362 9024 | GC, remodel, ADU | Arcata · Humboldt County | — | — |
| James L Parra | James L Parra | — | (714) 853 3273 | HVAC | Blue Lake · Humboldt County | — | — |
| James Stretch General Contractor | James Stretch General Contractor | — | (707) 845 2751 | GC, remodel, ADU | Ferndale · Humboldt County | — | — |
| James William Bass Jr | James William Bass Jr | — | (707) 786 4829 | GC, remodel, ADU | Ferndale · Humboldt County | — | — |
| Jamesons Screen Company | Jamesons Screen Company | jameson707@gmail.com | — | Windows, patio, painters | Mckinleyville · Humboldt County | — | — |
| Jason Besanceney Ag | Jason Besanceney Ag | — | (707) 672 2629 | GC, remodel, ADU | Ferndale · Humboldt County | — | — |
| Jay Giordano Construction | Jay Whitman Giordano | — | (707) 362 5749 | GC, remodel, ADU | Loleta · Humboldt County | — | — |
| Jaymes Refrigeration Service | Jayme Javier Gonzales | — | (707) 382 6978 | HVAC | Fortuna · Humboldt County | — | — |
| Jcs Builder | Jcs Builder | — | (707) 497 8554 | GC, remodel, ADU | Eureka · Humboldt County | — | — |
| Jds Construction INC | Daniel Edward Salinger | — | (707) 616 4425 | GC, remodel, ADU | Eureka · Humboldt County | — | — |
| Jeff Drywall | Jeff Drywall | — | (707) 362 4777 | Other | Rio Dell · Humboldt County | — | — |
| Jeff Noga Construction | Jeff Michael Noga | — | (707) 845 5628 | GC, remodel, ADU | Arcata · Humboldt County | — | — |