| Interactive Resources INC | Thomas King Butt | — | (510) 236 7435 | GC, remodel, ADU | Point Richmond · Contra Costa County | — | — |
| Intercept LLC | Arnaud Silvarelli | — | (510) 424 3984 | Other | Moraga · Contra Costa County | — | — |
| Interiors Of California INC | Roimoshe Levi | info@interiorsofcalifornia.com | (510) 833 8395 | GC, remodel, ADU | Walnut Creek · Contra Costa County | — | — |
| Interlink Tiling Company | Michael Jason Dwinell | — | (510) 325 9237 | GC, remodel, ADU | Lafayette · Contra Costa County | — | — |
| Interlock Pavers Incorporated | Brian Joseph Schmidt | — | (925) 407 4757 | Other | Walnut Creek · Contra Costa County | — | — |
| Interlock Plumbing | Anthony David Lorencillo | — | (510) 932 0391 | HVAC | Antioch · Contra Costa County | — | — |
| Interlocking Pavers By The Bay | Saira Jasmin Corona-Villanueva | — | (510) 830 8179 | Other | Richmond · Contra Costa County | — | — |
| International Fire Equipment Co Incorporated | Duerigen Peter | — | (510) 237 5000 | Other | Richmond · Contra Costa County | — | — |
| Intrepid Electronic Systems INC | Heather Lynn Lent | — | (510) 774 1551 | Electricians | Crockett · Contra Costa County | — | — |
| Ippolito Renovations INC | Rick Lee Ippolito | — | (415) 286 0104 | GC, remodel, ADU | Oakley · Contra Costa County | — | — |
| Ira Hastings | Ira Hastings | — | (925) 324 8663 | GC, remodel, ADU | Walnut Creek · Contra Costa County | — | — |
| Iri Landscape INC | Milic Djordje | — | (476) 554 8289 | Windows, patio, painters | Walnut Creek · Contra Costa County | — | — |
| Iron Horse Concrete | Iron Horse Concrete | jason@ironhorseconcrete.com | (925) 595 3951 | Other | Concord · Contra Costa County | — | — |
| Iron Horse Door Company | Gregory Andrew Napolitano | — | (925) 324 1301 | Other | Clayton · Contra Costa County | — | — |
| Iron Horse Windows And Glass Showers | Justin Dalton Miller | — | (925) 238 9039 | Windows, patio, painters | Concord · Contra Costa County | — | — |
| Iron Leaf Pros LLC | Robert James Powell | — | (925) 546 8121 | Windows, patio, painters | Concord · Contra Costa County | — | — |
| Ironcrest Development Group LLC | Payam Hashemi | — | (925) 486 9591 | GC, remodel, ADU | Danville · Contra Costa County | — | — |
| Ironedge Builders | James S Lee | — | (510) 478 4309 | GC, remodel, ADU | Richmond · Contra Costa County | — | — |
| Ironrock Builders | Ian Frederick Chapman | — | (925) 788 1827 | GC, remodel, ADU | Martinez · Contra Costa County | — | — |
| Ironwood Commercial Builders INC | Victoria Marie Brinkerhoff | — | (925) 609 8356 | GC, remodel, ADU | Concord · Contra Costa County | — | — |
| Ironwood Construction Company | Thomas Culbertson Iii Clark | — | (510) 524 8058 | GC, remodel, ADU | Kensington · Contra Costa County | — | — |
| Irrigation Sources | Irrigation Sources | — | (415) 518 6569 | Windows, patio, painters | San Ramon · Contra Costa County | — | — |
| Isaac Nathaniel Excavating & Paving | Isaac Nathaniel Excavating & Paving | — | (925) 325 7834 | Other | Antioch · Contra Costa County | — | — |
| Isaiah's Remodeling | Isaiah's Remodeling | — | (510) 409 3451 | GC, remodel, ADU | Richmond · Contra Costa County | — | — |
| Isidro Ibarra | Isidro Ibarra | — | (510) 499 3433 | Other | San Pablo · Contra Costa County | — | — |
| Isidro Martinez Construction | Christopher Robert Lopez | — | (415) 532 9859 | GC, remodel, ADU | Richmond · Contra Costa County | — | — |
| Iskra Electrical Services LLC | Andrii Yuzko | — | (424) 380 8157 | Electricians | El Cerrito · Contra Costa County | — | — |
| Isla Pools Service | Christopher Bryan Aldan | islapoolsllc@gmail.com | (925) 490 4655 | Pool | Concord · Contra Costa County | — | — |
| Islander Concrete | Islander Concrete | — | (925) 915 5240 | Other | Pittsburg · Contra Costa County | — | — |
| Israa Plumbing | Israa Plumbing | — | (925) 978 7196 | Other | Antioch · Contra Costa County | — | — |
| Italian Heritage Tile And Stone INC | Santangelo Salvatore | — | (925) 822 7037 | GC, remodel, ADU | Clayton · Contra Costa County | — | — |
| Ivan Sharp's Painting | Ivan Sharp's Painting | — | (925) 639 4826 | Windows, patio, painters | Concord · Contra Costa County | — | — |
| Ivs Fences & Iron Works | Vargas Ignacio Velasquez | — | (510) 230 4655 | Other | Richmond · Contra Costa County | — | — |
| J & A Whirlow Painting And Renovation | Jimmy Ray Whirlow | — | (925) 813 1131 | GC, remodel, ADU | Concord · Contra Costa County | — | — |
| J & B Fence | Matthew Dennis Julian | matt@jbfence.com | (510) 339 6371 | Windows, patio, painters | Pleasant Hill · Contra Costa County | — | — |
| J & C Bath Reglazing INC | Cristian Geovany Amaya Turcios | — | (925) 250 5385 | Other | Concord · Contra Costa County | — | — |
| J & C General Engineering | Jason Kimmick Carstairs | — | (925) 382 4307 | Other | Brentwood · Contra Costa County | — | — |
| J & D Roofing Services INC | Rocha Alejandro Juarez | info@jdroofingservices.com | (510) 426 2213 | Other roofers | Richmond · Contra Costa County | — | — |
| J & J's Final Coat Painting INC | Gary Joseph Sabel | — | (925) 687 5849 | Windows, patio, painters | Antioch · Contra Costa County | — | — |
| J & K Morga Construction | Jonny Francisco Carlos Diaz | jkmorga2004@gmail.com | (415) 505 9788 | GC, remodel, ADU | Richmond · Contra Costa County | — | — |