| 1 Haro 1 LLC | Ruben Terriquez | — | (408) 464 4564 | HVAC | San Jose · Santa Clara County | — | — |
| 1 Hour Drain Hotshot Restoration | Robert John Gallaher | — | (408) 825 1362 | HVAC | San Jose · Santa Clara County | — | — |
| 1 Master's Shop Construction INC | Aguayo Mario Escobedo | — | (818) 523 3884 | GC, remodel, ADU | Agoura Hills · Los Angeles County | — | — |
| 1 N 7 General Construction | Zhong Jinfan | — | (415) 370 9822 | GC, remodel, ADU | Oakland · Alameda County | — | — |
| 1 N Done Roofing Services INC | Octavio Rosas Gonzalez | — | (530) 933 8272 | Other roofers | Marysville · Yuba County | — | — |
| 1 Nation Construction INC | Robert Anthony Shea | — | (209) 406 4632 | GC, remodel, ADU | Stockton · San Joaquin County | — | — |
| 1 Oak Construction LLC | Dominique Haritzalde | — | (559) 206 3665 | Other | Clovis · Fresno County | — | — |
| 1 Oak Remodeling | Joshua Navid Keshmir | — | (877) 448 1625 | GC, remodel, ADU | Encino · Los Angeles County | — | — |
| 1 Of A Kine Wood Construction | Goodman Jason | — | (530) 638 6954 | GC, remodel, ADU | Cottonwood · Shasta County | — | — |
| 1 Original Construction INC | George Vladimir Troosh | interested@domainmarket.com | (415) 420 5509 | GC, remodel, ADU | San Francisco · San Francisco County | — | — |
| 1 Smart Build INC | Isaac Sade | — | (866) 419 8840 | GC, remodel, ADU | Woodland Hills · Los Angeles County | — | — |
| 1 Solorio INC | Solorio Alex | — | (714) 578 4709 | GC, remodel, ADU | Orange · Orange County | — | — |
| 1 Source Electric | Jeffrey Ryan Vickland | — | (916) 844 8811 | Electricians | Cameron Park · El Dorado County | — | — |
| 1 Source Electrical INC | Carl Joseph Pizzuto | — | (760) 739 1987 | Electricians | San Marcos · San Diego County | — | — |
| 1 Source Material Handling INC | John M Howard | — | (818) 838 1688 | Other | Glendale · Los Angeles County | — | — |
| 1 St California Construction INC | Zamani Alireza | — | (626) 533 5673 | GC, remodel, ADU | Pasadena · Los Angeles County | — | — |
| 1 St Choice Energy Builders INC | Maor Tziun Knafo | — | (818) 277 0514 | GC, remodel, ADU | Tarzana · Los Angeles County | — | — |
| 1 St Choice Restoration LLC | Allen Danilof | — | (818) 912 3232 | GC, remodel, ADU | Porter Ranch · Los Angeles County | — | — |
| 1 Step By Step Construction | Tony D'arcy Muir | — | (925) 597 4648 | GC, remodel, ADU | Vallejo · Solano County | — | — |
| 1 Stop Builders | Rahlin Yaaqov | — | (877) 220 5575 | GC, remodel, ADU | Mission Hills · Los Angeles County | — | — |
| 1 Stop Building Construction | Angel Villegas Gonzalez | — | (562) 318 7515 | GC, remodel, ADU | Long Beach · Los Angeles County | — | — |
| 1 Stop Electric | Aaron Austin | — | (559) 636 0595 | Electricians | Visalia · Tulare County | — | — |
| 1 Stop Kitchen & Bath LLC | Mike Amin Arid | — | (818) 708 7777 | GC, remodel, ADU | Reseda · Los Angeles County | — | — |
| 1 Struct | 1 Struct | info@struct.com | (831) 975 9248 | Electricians | Salinas · Monterey County | — | — |
| 1 Superior Electric INC | Rick Daniel Sullivan | info@superior-electric.com | (949) 933 2749 | Electricians | Newport Beach · Orange County | — | — |
| 1 Teamwork Fire Protection | Christopher Alan Cronin | — | (714) 309 2869 | Other | Newport Beach · Orange County | — | — |
| 1 Teamwork Fire Protection LLC | Austin Allen Holmes | — | (909) 390 8392 | Other | Rancho Cucamonga · San Bernardino County | — | — |
| 1 Tom Plumber Anaheim / Brea | Rickie Machie Moore | — | (714) 769 6300 | Other | Anaheim · Orange County | — | — |
| 1 Tom Plumber Concord | Dennis Earl Debenham | — | (925) 922 0594 | Other | Concord · Contra Costa County | — | — |
| 1 Up Construction INC | Roger Arlen Mills | — | (925) 503 7024 | GC, remodel, ADU | Brentwood · Contra Costa County | — | — |
| 1+ | Kenneth William Akiyoshi | — | (323) 316 4812 | GC, remodel, ADU | Monterey Park · Los Angeles County | — | — |
| 1-800 Plumber + Air Of Monterey | David Charles De Cato | — | (831) 277 7258 | HVAC | Seaside · Monterey County | — | — |
| 1-800 Water Damage Of Solano County | 1-800 Water Damage Of Solano County | info@1800waterdamage.com | (800) 928-3732 | Restoration | Fairfield · Solano County | — | — |
| 1-800 Water Damage Of West San Jose And Sunnvale | Bahram Nosrati Shamlou | — | (408) 859 5559 | GC, remodel, ADU | San Jose · Santa Clara County | — | — |
| 1-800-coolness | Phillip Robert Paquin | — | (800) 266 5637 | HVAC | Fullerton · Orange County | — | — |
| 1-877 Appliance Repair INC | Ayriyan Gary | 1877appliance@gmail.com | (858) 222 9542 | HVAC | La Mesa · San Diego County | — | — |
| 1-888-heat-pumps | John Linus Grimsich | — | (888) 432 8786 | HVAC | Berkeley · Alameda County | — | — |
| 1-888-wow-1 Day! Painting | Zachary Von Strehl Jaggers | — | (619) 955 0071 | Windows, patio, painters | San Diego · San Diego County | — | — |
| 1-stop Integrated Solutions LLC | Luis Alberto Reyna Gaytan | — | (760) 705 5639 | Other | Escondido · San Diego County | — | — |
| 1-take Electrical | Victor Alexander Gonzalez | — | (559) 213 4337 | Electricians | Madera · Madera County | — | — |