| J D Lucas Builders | J D Lucas Builders | — | (925) 382 8579 | GC, remodel, ADU | Antioch · Contra Costa County | — | — |
| J D P Professional Painting | J D P Professional Painting | — | (925) 497 6305 | Windows, patio, painters | Pittsburg · Contra Costa County | — | — |
| J D S Construction | Jeffrey Dennis Schwarz | — | (925) 899 9180 | GC, remodel, ADU | Orinda · Contra Costa County | — | — |
| J Dicus Landscape Construction INC | Joseph Anthony Jr Dicus | — | (925) 260 5838 | Windows, patio, painters | Danville · Contra Costa County | — | — |
| J Dorantes Construction | Lopez Jesus Dorantes | — | (925) 349 9613 | GC, remodel, ADU | Concord · Contra Costa County | — | — |
| J E General Construction INC | Jose Agustin Sarria | — | (415) 424 5507 | GC, remodel, ADU | Pinole · Contra Costa County | — | — |
| J E Landscaping | J E Landscaping | — | (925) 206 7705 | Windows, patio, painters | Walnut Creek · Contra Costa County | — | — |
| J E O Construction | Jeff Edward Olson | — | (925) 595 5927 | GC, remodel, ADU | Pleasant Hill · Contra Costa County | — | — |
| J E S C O | J E S C O | — | (925) 383 5952 | Electricians | Concord · Contra Costa County | — | — |
| J F Nickels Construction | John Fredrick Nickels | — | (925) 932 2249 | GC, remodel, ADU | Walnut Creek · Contra Costa County | — | — |
| J Fidler Construction | James Andrew Fidler | — | (925) 818 8969 | GC, remodel, ADU | Martinez · Contra Costa County | — | — |
| J G Absolute Painting | J G Absolute Painting | — | (925) 305 7489 | Windows, patio, painters | Antioch · Contra Costa County | — | — |
| J G Construction | Jose Guadalupe Jr Aguirre | — | (925) 864 1074 | GC, remodel, ADU | Concord · Contra Costa County | — | — |
| J George Construction | John Edward George | jgconstructionllc2024@gmail.com | (925) 595 2877 | GC, remodel, ADU | Concord · Contra Costa County | — | — |
| J H Electric | Jorge Ivan Henning Garcia | — | (510) 472 5319 | Electricians | El Sobrante · Contra Costa County | — | — |
| J J Construction | Victor Nolasco Jr Pascua | — | (408) 849 2228 | Electricians | El Sobrante · Contra Costa County | — | — |
| J J Enciso Painting & Restoration INC DBA Enciso Painting | Jose De Jesus Enciso Mendoza | — | (510) 798 4470 | Windows, patio, painters | Richmond · Contra Costa County | — | — |
| J J Framing | J J Framing | — | (415) 717 5311 | GC, remodel, ADU | Richmond · Contra Costa County | — | — |
| J J H Construction Services INC | Mendez Heriberto Hernandez | — | (925) 639 8585 | GC, remodel, ADU | Concord · Contra Costa County | — | — |
| J J Pump Service | Juarez Jorge | — | (925) 260 7727 | Other | Oakley · Contra Costa County | — | — |
| J Jones Construction INC | Justin Christopher Jones | — | (510) 825 8082 | GC, remodel, ADU | Discovery Bay · Contra Costa County | — | — |
| J L Builders And Associates | John Henry Lucasey | — | (510) 774 8140 | GC, remodel, ADU | Alamo · Contra Costa County | — | — |
| J L Construction | Luong Jason | — | (310) 386 8438 | GC, remodel, ADU | Danville · Contra Costa County | — | — |
| J L Construction | Ioannis John Lazaridis | — | (510) 799 3232 | GC, remodel, ADU | Rodeo · Contra Costa County | — | — |
| J L Construction | Jorge Luis Lopez | — | (925) 363 4634 | GC, remodel, ADU | Pleasant Hill · Contra Costa County | — | — |
| J L Construction | Jose Felix Lozano | — | (925) 765 0925 | GC, remodel, ADU | Concord · Contra Costa County | — | — |
| J L Ford Const | J L Ford Const | — | (510) 693 2974 | GC, remodel, ADU | Richmond · Contra Costa County | — | — |
| J L Tile INC | Lascon Jesus | — | (925) 759 6297 | Other | Antioch · Contra Costa County | — | — |
| J L Yardscapes | J L Yardscapes | — | (925) 783 6070 | Windows, patio, painters | Antioch · Contra Costa County | — | — |
| J M Drummond Landscape Management | J M Drummond Landscape Management | — | (925) 783 6299 | Windows, patio, painters | Oakley · Contra Costa County | — | — |
| J M Drywall Dimensions | Jose Jaime Marquez-jauregui | micah@micahrich.com | (510) 222 1795 | GC, remodel, ADU | El Sobrante · Contra Costa County | — | — |
| J M Fire Systems | J M Fire Systems | josh@jmfiresystems.com | (925) 550 9928 | Other | Martinez · Contra Costa County | — | — |
| J M Insulation INC | Valdovinos Javier Medina | — | (925) 305 7682 | Other | Pittsburg · Contra Costa County | — | — |
| J M J Property Management | J M J Property Management | — | (925) 330 8265 | GC, remodel, ADU | Walnut Creek · Contra Costa County | — | — |
| J M L Construction | Robert Louis Pastor | brian@jmlconstruction.com | (573) 429-4962 | GC, remodel, ADU | Clayton · Contra Costa County | — | — |
| J M L Construction | Jason Mark Laub | brian@jmlconstruction.com | (573) 429-4962 | GC, remodel, ADU | Concord · Contra Costa County | — | — |
| J M Z Concrete INC | Alfredo Lara Jimenez | — | (925) 520 9673 | Other | Concord · Contra Costa County | — | — |
| J Monti Co INC | Danielle Louise De Pianto | — | (510) 527 2660 | Other | El Cerrito · Contra Costa County | — | — |
| J N Plumbing & Rooter INC | Jose Silverio Navarro | — | (510) 754 9360 | GC, remodel, ADU | Oakley · Contra Costa County | — | — |
| J O D R INC | Miguel Angel Del Rio | — | (415) 637 1986 | GC, remodel, ADU | Concord · Contra Costa County | — | — |