| 40 Plus Home Improvement INC | Sun Yuan | — | (626) 525 1861 | HVAC | Corona · Riverside County | — | — |
| 40 Traffic & Construction INC | Steven Ray Forde | — | (530) 639 9987 | Other | Anderson · Shasta County | — | — |
| 405 Drywall Co | Hugo Herrera | — | (323) 228 1551 | Other | Bell · Los Angeles County | — | — |
| 405 HVAC | Hossein Barekatain | — | (703) 899 0047 | HVAC | Irvine · Orange County | — | — |
| 408 Builders INC | Inderjeet Singh | — | (408) 609 1643 | GC, remodel, ADU | San Jose · Santa Clara County | — | — |
| 408 Electric | Shawn Aaron Moore | — | (408) 688 6840 | Electricians | San Jose · Santa Clara County | — | — |
| 408 Real Estate | 408 Real Estate | — | (408) 316 5954 | GC, remodel, ADU | Campbell · Santa Clara County | — | — |
| 41 Painting | 41 Painting | — | (916) 595 3422 | Windows, patio, painters | Rancho Cordova · Sacramento County | — | — |
| 411 Heating & AC LLC | Mauluddi Said Opeyany | — | (925) 953 3007 | HVAC | Clayton · Contra Costa County | — | — |
| 411 Painting | 411 Painting | — | (707) 393 7750 | Windows, patio, painters | Santa Rosa · Sonoma County | — | — |
| 413 Builders | 413 Builders | — | (310) 207 1300 | GC, remodel, ADU | Los Angeles · Los Angeles County | — | — |
| 415 Construction & Electrical | Raul Del Campo Gonzales | — | (415) 260 0984 | Electricians | San Francisco · San Francisco County | — | — |
| 415 Design+build | Larry Ely Fonseca | — | (415) 347 5627 | GC, remodel, ADU | Brisbane · San Mateo County | — | — |
| 415 Drywall | 415 Drywall | — | (408) 722 2069 | Other | San Bruno · San Mateo County | — | — |
| 415 Electric | Gregory Leonard Barnes | — | (415) 578 6000 | Electricians | San Francisco · San Francisco County | — | — |
| 415 Remodeling INC | Aaron Lee Gordon | — | (415) 682 4242 | GC, remodel, ADU | San Francisco · San Francisco County | — | — |
| 415 Roofing Corp | Garcia-apantenco Manuel | — | (415) 637 3375 | Other roofers | San Francisco · San Francisco County | — | — |
| 4214 Fulton Builders INC | Ara Kevork Karajerjian | — | (818) 817 9300 | GC, remodel, ADU | Studio City · Los Angeles County | — | — |
| 425 General Engineering INC | Alonso Ojeda | info@general-engineering.com | (510) 342 8013 | Other | Vacaville · Solano County | — | — |
| 4291 Tree Services LLC | Evan William Jones | impallari@gmail.com | (844) 772 4291 | Other | Placerville · El Dorado County | — | — |
| 43five60 Construction Group INC | Steven Paul Barrera | — | (323) 708 0772 | GC, remodel, ADU | Covina · Los Angeles County | — | — |
| 444 Electric INC | Christopher Michael Lawley | — | (530) 321 9210 | Electricians | Durham · Butte County | — | — |
| 45 Degree Plumbing INC | Brandon Charles Sr Brickey | — | (805) 315 4056 | Other | Lompoc · Santa Barbara County | — | — |
| 45 Degrees Finish Carpentry INC | Miguel Angel Adame | — | (323) 810 0993 | Other | Alhambra · Los Angeles County | — | — |
| 457 Pool INC | Bradley Edward Stanley | — | (310) 457 7665 | Pool | Malibu · Los Angeles County | — | — |
| 4645 Gb LLC DBA Jem Construction & Development | James Moushoul | — | (310) 560 3700 | GC, remodel, ADU | Sherman Oaks · Los Angeles County | — | — |
| 47 Painting INC | Manuel Jr Villegas | — | (209) 658 6306 | Windows, patio, painters | Merced · Merced County | — | — |
| 47th Place Carpet One Floor & Home | Jhana Derooy Eddings | — | (559) 674 4621 | Other | Madera · Madera County | — | — |
| 481 Plumb | 481 Plumb | — | (858) 342 5796 | Other | Del Mar · San Diego County | — | — |
| 49 Plumbing | 49 Plumbing | — | (916) 825 5230 | Other | La Jolla · San Diego County | — | — |
| 49er Electric | Grahame Kenneth Tadman | info@49erelectric.com | (530) 913 6832 | Electricians | Nevada City · Nevada County | — | — |
| 49er Electric | Daron Kenneth Tadman | info@49erelectric.com | (530) 308 4660 | Electricians | Truckee · Nevada County | — | — |
| 49er Plumbing & Drain | Dillon Matthew Gunnels | — | (530) 271 1270 | Other | Grass Valley · Nevada County | — | — |
| 49er Rooter And Drain Service INC | Michael Anthony Pizzano | — | (831) 818 0519 | Other | Copperopolis · Calaveras County | — | — |
| 49er Water Services | Charles Thomas Burr | — | (530) 559 8089 | Electricians | Nevada City · Nevada County | — | — |
| 4:13 Gc Services | Michael Shawn Johnson | — | (714) 450 2367 | GC, remodel, ADU | Orange · Orange County | — | — |
| 4A Electric & Building | Brian Vale Foraker | — | (831) 332 3374 | Electricians | Santa Cruz · Santa Cruz County | — | — |
| 4A Landscape | Aldo Alejandro Vara Olivares | — | (949) 394 0356 | Windows, patio, painters | Costa Mesa · Orange County | — | — |
| 4B Electric INC | Michael Robert Barnett | — | (619) 723 0209 | Electricians | El Cajon · San Diego County | — | — |
| 4C Construction Systems LLC | Yonah Aharon Naftaly | — | (650) 200 3182 | GC, remodel, ADU | Hayward · Alameda County | — | — |