| Let's Dig INC | James Vernon Easterday | — | (925) 812 4771 | GC, remodel, ADU | Crockett · Contra Costa County | — | — |
| Letts Plumbing | Shane Russell Letts | — | (925) 687 1884 | Other | Concord · Contra Costa County | — | — |
| Level 7 Construction INC | Walter Obdulio Gomez Garcia | office@level7construction.net | (925) 383 0283 | Other roofers | Brentwood · Contra Costa County | — | — |
| Level A Solutions INC | Jonathan Charles Taylor | — | (925) 228 8709 | Other | Martinez · Contra Costa County | — | — |
| Level Contractor | Level Contractor | — | (818) 297 2920 | GC, remodel, ADU | San Ramon · Contra Costa County | — | — |
| Level Five Painting | Level Five Painting | — | (510) 685 8432 | Windows, patio, painters | Richmond · Contra Costa County | — | — |
| Level Up Construction Service | Toan Van Pham | — | (925) 788 9849 | HVAC | San Ramon · Contra Costa County | — | — |
| Level Up Floors | Level Up Floors | — | (925) 914 9603 | Other | Concord · Contra Costa County | — | — |
| Levi's Construction INC | Samuel Levi Lopez | — | (510) 543 1182 | GC, remodel, ADU | El Sobrante · Contra Costa County | — | — |
| Lewis & Lewis Carpets | Lewis & Lewis Carpets | contact@sansoxygen.com | (925) 939 2145 | Other | Concord · Contra Costa County | — | — |
| Lewkowicz & Associates INC | James Morrison Lewkowicz | — | (925) 890 3632 | GC, remodel, ADU | Danville · Contra Costa County | — | — |
| Lexi Development & Construction | William Edward Bucher | — | (925) 366 5201 | GC, remodel, ADU | Lafayette · Contra Costa County | — | — |
| Lg Concrete INC | Lino Gomez-Canales | info@lgconcrete.com | (925) 698 4813 | Other | Pittsburg · Contra Costa County | — | — |
| Lg Engineering | Lg Engineering | — | (510) 932 8212 | Other | Richmond · Contra Costa County | — | — |
| Lg Plumbing | Lg Plumbing | — | (925) 374 2863 | Other | Concord · Contra Costa County | — | — |
| Lh Construction | Thet Su Lynn Htut | — | (510) 685 9766 | GC, remodel, ADU | Richmond · Contra Costa County | — | — |
| Liaison Concrete Construction | Markus Paul Don Czirban | — | (559) 580 3860 | Windows, patio, painters | Concord · Contra Costa County | — | — |
| Liaison Hardscapes | Shawn Daniel Czirban | — | (415) 805 3404 | Windows, patio, painters | Concord · Contra Costa County | — | — |
| Lian's Well Built Construction LLC | Yontao Lian | — | (510) 229 0065 | GC, remodel, ADU | San Pablo · Contra Costa County | — | — |
| Liberato's Landscaping | Liberato's Landscaping | — | (510) 860 5826 | Windows, patio, painters | San Pablo · Contra Costa County | — | — |
| Liberty Pavers Stones INC | Frederico Quintino Siqueira | — | (510) 779 8932 | Other | Richmond · Contra Costa County | — | — |
| Liedstrand Landscape Construction INC | Timothy Roy Liedstrand | — | (925) 324 0535 | Windows, patio, painters | Walnut Creek · Contra Costa County | — | — |
| Life Line Painting | Life Line Painting | — | (925) 727 9478 | Windows, patio, painters | Antioch · Contra Costa County | — | — |
| Lifesaver Plumbing And Rooter | Lifesaver Plumbing And Rooter | — | (510) 810 2788 | Other | Pinole · Contra Costa County | — | — |
| Lifestyle Fiberglass Pools | Ralph Brian Galvond | — | (925) 378 5752 | Pool | Brentwood · Contra Costa County | — | — |
| Lift & Transfer Specialists INC | Craig John Coogan | — | (925) 240 8474 | Other | Brentwood · Contra Costa County | — | — |
| Light House Electric | Ryan Michael Bidwell | — | (925) 639 8698 | Electricians | Walnut Creek · Contra Costa County | — | — |
| Lighthouse Painting Co | Kratsas Nikolaos | — | (209) 221 5491 | Windows, patio, painters | Pittsburg · Contra Costa County | — | — |
| Liko Industries INC | Steve John Klouvidakis | — | (510) 867 1928 | Other | Walnut Creek · Contra Costa County | — | — |
| Lilais Electric | Artem Andreevych Lelaisromant | — | (424) 541 8421 | Electricians | San Ramon · Contra Costa County | — | — |
| Lili Construction LLC | Dvir Brakha | — | (510) 333 2272 | GC, remodel, ADU | Kensington · Contra Costa County | — | — |
| Lilypad Ev LLC | Jeffrey Lynn Nelson | hello@lilypadev.com | (800) 772 2300 | EV chargers | Martinez · Contra Costa County | — | — |
| Lima Construction | Yenci Yomar Lima Hernandez | — | (650) 465 0976 | GC, remodel, ADU | Brentwood · Contra Costa County | — | — |
| Limelite Painting | Limelite Painting | — | (415) 235 9692 | Windows, patio, painters | Richmond · Contra Costa County | — | — |
| Limitless Building Concepts | Mehmedic Salih | — | (925) 575 1531 | GC, remodel, ADU | Concord · Contra Costa County | — | — |
| Limitless Excavating And Grading | Limitless Excavating And Grading | — | (925) 766 1233 | Other | Concord · Contra Costa County | — | — |
| Limon Construction | Armando Mendoza Limon | — | (510) 913 6003 | Electricians | El Sobrante · Contra Costa County | — | — |
| Limon Electric & Construction | Juan Antonio Jr Limon | — | (510) 938 1960 | Electricians | Antioch · Contra Costa County | — | — |
| Linares Construction INC | Edgar Edenilson Linares | — | (415) 574 9092 | GC, remodel, ADU | Richmond · Contra Costa County | — | — |
| Linares Electric INC | Nestor Rigoberto Linares | — | (925) 234 3222 | Electricians | Brentwood · Contra Costa County | — | — |