| Louis Quality Construction | Louis Ruiyi Xie | — | (510) 410 2282 | GC, remodel, ADU | El Cerrito · Contra Costa County | — | — |
| Louis S Zocchi | Louis S Zocchi | — | (925) 685 9070 | GC, remodel, ADU | Concord · Contra Costa County | — | — |
| Louis Windhurst | Louis Windhurst | — | (925) 330 2102 | GC, remodel, ADU | Orinda · Contra Costa County | — | — |
| Loukos Construction INC | Themis Theocharis Loukos | — | (925) 263 2806 | GC, remodel, ADU | Danville · Contra Costa County | — | — |
| Lovett & Lovett Roofing Co INC | Jordon Holt Lovett | — | (510) 532 7663 | Other roofers | Martinez · Contra Costa County | — | — |
| Low Voltage | Bryan Ganal Bucao | — | (408) 658 7404 | Other | Brentwood · Contra Costa County | — | — |
| Low Voltage Dreams INC | Nelson Ivan Pavon | — | (925) 285 7766 | Other | Antioch · Contra Costa County | — | — |
| Loza Painting | Loza Painting | — | (925) 864 3722 | Windows, patio, painters | Clayton · Contra Costa County | — | — |
| Lozano Landscaping INC | Lozano Juan | — | (925) 595 3546 | Windows, patio, painters | Pittsburg · Contra Costa County | — | — |
| Lozano Tree Care INC | Brian Lozano | — | (925) 504 3294 | Other | Pittsburg · Contra Costa County | — | — |
| Lozano's Ornamental INC | Carrillo Ricardo Lozano | — | (925) 966 7185 | Other | Antioch · Contra Costa County | — | — |
| LP Electrical Contractor | Lee R Peneranda | — | (805) 332 0855 | Electricians | Antioch · Contra Costa County | — | — |
| Lpc Construction INC | Christopher Paul Leary | — | (925) 383 1112 | GC, remodel, ADU | Walnut Creek · Contra Costa County | — | — |
| Lrj Construction LLC | Luis Rafael Osorio Lopez | estimating@lrjconstruction.com | (510) 570 4972 | GC, remodel, ADU | Richmond · Contra Costa County | — | — |
| Lrl Builders INC | Frenkel Raz | info@lrlbuilders.com | (925) 905 9995 | GC, remodel, ADU | Walnut Creek · Contra Costa County | — | — |
| Lrv Builders INC | Luis Roberto Valdovinos Trejo | — | (408) 209 5138 | GC, remodel, ADU | Concord · Contra Costa County | — | — |
| Ltg Construction | Eduardo Manuel La Torre | — | (510) 472 6767 | GC, remodel, ADU | Danville · Contra Costa County | — | — |
| Lubomir Skokan DBA Delta Windows | Lubomir Skokan DBA Delta Windows | — | (415) 272 5690 | Windows, patio, painters | Brentwood · Contra Costa County | — | — |
| Lucas Construction | Steven Charles Lucas | — | (925) 234 2045 | GC, remodel, ADU | Bethel Island · Contra Costa County | — | — |
| Lucas Electrical | Cesar Augusto Lucas | — | (925) 813 8188 | Electricians | Antioch · Contra Costa County | — | — |
| Lucas Electrical INC | Cesar Augusto Lucas | — | (925) 813 8188 | Electricians | Antioch · Contra Costa County | — | — |
| Lucas Paving INC | Anthony Joseph Perez | — | (925) 808 0853 | GC, remodel, ADU | Martinez · Contra Costa County | — | — |
| Lucchese And Sons | Lucchese And Sons | — | (925) 672 8275 | GC, remodel, ADU | Clayton · Contra Costa County | — | — |
| Lucid Builders | Francisco Javier Jr Alcaraz | john@lucidbuilders.com | (510) 260 7324 | GC, remodel, ADU | El Cerrito · Contra Costa County | — | — |
| Luis Alvarez Construction | Luis David Alvarez | — | (925) 639 2808 | GC, remodel, ADU | Pittsburg · Contra Costa County | — | — |
| Luis F Vilchez | Luis F Vilchez | — | (925) 969 9932 | HVAC | Concord · Contra Costa County | — | — |
| Luis Preciado Construction | Luis Mario Jr Preciado | — | (925) 640 4634 | GC, remodel, ADU | Martinez · Contra Costa County | — | — |
| Luis Rafael Silva - Santisteban DBA Silva Contractor | Silva Contractor | — | (925) 381 8696 | HVAC | Pleasant Hill · Contra Costa County | — | — |
| Luis Rios Lopez | Luis Rios Lopez | — | (925) 400 5526 | Windows, patio, painters | Pacheco · Contra Costa County | — | — |
| Lujano Landscape | Lujano Landscape | — | (925) 768 1799 | Windows, patio, painters | Oakley · Contra Costa County | — | — |
| Luke Adam Morrison General Contractor | Luke Adam Morrison General Contractor | — | (949) 374 3897 | GC, remodel, ADU | Lafayette · Contra Costa County | — | — |
| Luke's Generators | Luke's Generators | — | (925) 871 9022 | Electricians | Concord · Contra Costa County | — | — |
| Luma Engineering Contractors INC | Xiomara Jaqueline Pfaff | — | (925) 499 2668 | Electricians | Oakley · Contra Costa County | — | — |
| Lumen Electric LLC | Robert David Ducote | — | (408) 313 9972 | Electricians | Alamo · Contra Costa County | — | — |
| Lumenati Electric | Castro Jimmy | — | (510) 375 8138 | Electricians | Pinole · Contra Costa County | — | — |
| Luminous Roofing | Jauregui Jesus | — | (510) 495 7265 | Other roofers | Hercules · Contra Costa County | — | — |
| Lusky Construction INC | Amiram Lusky | — | (510) 512 5066 | GC, remodel, ADU | Concord · Contra Costa County | — | — |
| Lutris Electric INC | Lewis Eleseo Lopez | — | (510) 418 7493 | Electricians | Orinda · Contra Costa County | — | — |
| Lux Custom Carpentry | Joshua Edwardo Gutierrez | — | (925) 658 2662 | Other | Concord · Contra Costa County | — | — |
| Lux Renovations | Lux Renovations | — | (510) 904 8535 | GC, remodel, ADU | Discovery Bay · Contra Costa County | — | — |