| 360 Windows And Doors | Zachary Kayem Morrison | buildzoomsupport@blockrenovation.com | (619) 331 5246 | GC, remodel, ADU | San Diego · San Diego County | — | — |
| 361 Construction INC | Sasa Saratlija | — | (415) 881 8787 | Electricians | Oakland · Alameda County | — | — |
| 365 Cleaning & Restoration | Leif Aaron Riley | jamil@symonsfp.com | (858) 652 9927 | GC, remodel, ADU | San Diego · San Diego County | — | — |
| 365 Construction INC | Mickey Carl Bearden | — | (626) 599 2002 | GC, remodel, ADU | Irwindale · Los Angeles County | — | — |
| 365 Demolition INC | Ohad Maloul | — | (818) 356 1731 | GC, remodel, ADU | Woodland Hills · Los Angeles County | — | — |
| 365 Electric INC | Jose Martin Huerta | — | (424) 420 3277 | Electricians | Carson · Los Angeles County | — | — |
| 365 Furniture Assembly | 365 Furniture Assembly | — | (415) 699 4556 | Other | Concord · Contra Costa County | — | — |
| 365 Plumbing & Rooter | 365 Plumbing & Rooter | — | (415) 368 3450 | Other | Daly City · San Mateo County | — | — |
| 365 Plumbing INC | Fares Belanteur | — | (619) 724 8550 | Other | La Mesa · San Diego County | — | — |
| 365 Pros Pools INC | Fernando Ramirez | — | (661) 313 0870 | Pool | Paramount · Los Angeles County | — | — |
| 365 Restoration Services INC | Samantha Meltz | — | (661) 287 9717 | GC, remodel, ADU | Santa Clarita · Los Angeles County | — | — |
| 3677 Columbia LLC | Ahmed Samih Eldahmy | — | (619) 313 1061 | GC, remodel, ADU | San Diego · San Diego County | — | — |
| 369 Construction Co INC | Qi Hua| Zhao Qi-hua Zhao | — | (415) 828 1131 | GC, remodel, ADU | Daly City · San Mateo County | — | — |
| 38 Degrees North Latitude Builders INC | Paul Flores Blickman | — | (415) 456 0937 | GC, remodel, ADU | San Rafael · Marin County | — | — |
| 38th Parallel LLC | Hojin Lim | — | (213) 601 3486 | Windows, patio, painters | Los Angeles · Los Angeles County | — | — |
| 395 Electric INC | John Michael Jr King | — | (714) 876 7023 | Electricians | Mammoth Lakes · Mono County | — | — |
| 395 Engineering | Eric Magana | — | (951) 529 1204 | Other | Jurupa Valley · Riverside County | — | — |
| 396 Roofing | Francisco Javier Diaz Acosta | — | (818) 913 1248 | Other roofers | Arleta · Los Angeles County | — | — |
| 3:10 Timber Services | Anthony Joseph Minaldi | kingslynn@timberservices.com | (559) 580 0091 | Other | Mariposa · Mariposa County | — | — |
| 3:16 Plumbing INC | Israel Joel Vasquez | — | (669) 206 7177 | Other | Los Banos · Merced County | — | — |
| 3:23 Metal Works INC | Christopher Robert Keys | support@metalworks.com | (442) 320 3237 | Other | Fallbrook · San Diego County | — | — |
| 3:23 Mountain Men | Jordan Alexander Esquivel | — | (831) 220 4552 | Windows, patio, painters | Mariposa · Mariposa County | — | — |
| 3A Construction & Maintenance INC | Alan Lee Hance | — | (661) 979 2765 | Electricians | Bakersfield · Kern County | — | — |
| 3A Genius Remodeling Corp | Eli Shalom Itshak | — | (818) 267 7607 | GC, remodel, ADU | West Hills · Los Angeles County | — | — |
| 3B Construction | Gutierrez Gustavo Balderas | — | (916) 955 7703 | GC, remodel, ADU | Sacramento · Sacramento County | — | — |
| 3B Construction Company LLC | Brandon Gene Madeira Wilcox | guy@infinitydesignbuild.com | (760) 473 7125 | GC, remodel, ADU | Encinitas · San Diego County | — | — |
| 3B Group LLC | Celso Barcena | — | (323) 397 1776 | Electricians | Los Angeles · Los Angeles County | — | — |
| 3B Investors INC | Jiri Kocian | — | (831) 444 5348 | GC, remodel, ADU | Salinas · Monterey County | — | — |
| 3B T's Construction Company | Raymond Jin Song Tan | — | (415) 859 9289 | GC, remodel, ADU | San Francisco · San Francisco County | — | — |
| 3C Construction INC | Juan Carlos Acosta | — | (626) 625 4626 | GC, remodel, ADU | Mira Loma · Riverside County | — | — |
| 3C Controls | Christopher D Lewis | — | (805) 540 3363 | Electricians | San Luis Obispo · San Luis Obispo County | — | — |
| 3C Electric Company | Zachariah James Crofoot | — | (805) 245 2464 | Electricians | Lompoc · Santa Barbara County | — | — |
| 3C Fencing INC | Cesar Omar Cuenca Camacho | info@3cfencing.com | (805) 621 3264 | Other | Santa Maria · Santa Barbara County | — | — |
| 3c's Refinishing & Painting | 3c's Refinishing & Painting | — | (714) 366 4159 | Windows, patio, painters | Anaheim · Orange County | — | — |
| 3cab Electric INC | Juan Miguel Cerna Aguilar | — | (323) 901 5243 | Electricians | Los Angeles · Los Angeles County | — | — |
| 3cm Corporation | Alexander Harvey Watts | — | (909) 534 1548 | GC, remodel, ADU | Loma Linda · San Bernardino County | — | — |
| 3D Builders | 3D Builders | — | (805) 698 2940 | GC, remodel, ADU | Santa Barbara · Santa Barbara County | — | — |
| 3D Building Company | Romero Antonio Navarro | 3dbuildingeurope@gmail.com | (650) 826 7763 | GC, remodel, ADU | Santa Rosa · Sonoma County | — | — |
| 3D Built | Omar Mohammad Abu Afifeh | — | (916) 399 3575 | Electricians | Roseville · Placer County | — | — |
| 3D Coating And Painting | Israel Rios | — | (714) 727 7799 | Windows, patio, painters | Tustin · Orange County | — | — |