| Trimble Construction | Daniel Harold Trimble | — | (415) 453 0600 | GC, remodel, ADU | San Anselmo · Marin County | — | — |
| Trimmerfish Building & Repair | Trimmerfish Building & Repair | — | (415) 755 0595 | GC, remodel, ADU | San Rafael · Marin County | — | — |
| Trinidad Builders | Trinidad Builders | — | (415) 302 1500 | GC, remodel, ADU | Novato · Marin County | — | — |
| Trinity Property Management | Trinity Property Management | — | (760) 487-1130 | Property managers | Cardiff · Marin County | — | — |
| True Blue Builders | True Blue Builders | — | (415) 517 6953 | GC, remodel, ADU | San Rafael · Marin County | — | — |
| True North Construction INC | Stephen Layne Crutchfield | info@truenorthconstruction.com | (415) 850 3405 | GC, remodel, ADU | San Rafael · Marin County | — | — |
| Truegreen Landscape INC | Giovanni Edsel Rodriguez Mendoza | — | (707) 495 9240 | Windows, patio, painters | Greenbrae · Marin County | — | — |
| Tuatagaloa Contracting | Gerardus Mauritius Na Tuatagaloa | — | (415) 370 9699 | Other | San Rafael · Marin County | — | — |
| Turley Construction | Turley Shannon | — | (415) 305 9761 | GC, remodel, ADU | Novato · Marin County | — | — |
| Turnbull Tile | Turnbull Tile | — | (415) 456 2917 | Other | San Anselmo · Marin County | — | — |
| Turnd INC | Tod Dimov Jordanov | — | (415) 279 7385 | GC, remodel, ADU | Novato · Marin County | — | — |
| Turnd Socal INC | Tod Dimov Jordanov | — | (415) 279 7385 | GC, remodel, ADU | Novato · Marin County | — | — |
| Twing Incorporated | Michael Jerome Twing | — | (415) 380 1988 | GC, remodel, ADU | San Rafael · Marin County | — | — |
| Twins Landscaping | Zulma Alondra Magana Cardenas | — | (415) 716 0631 | Windows, patio, painters | Novato · Marin County | — | — |
| Tww Associates | Thomas White Warrington | — | (415) 328 4450 | GC, remodel, ADU | Novato · Marin County | — | — |
| U S Glass & Shower Door | Khajehgani Bahman | wagner@usglassshowerdoor.com | (415) 722 1124 | Windows, patio, painters | Novato · Marin County | — | — |
| U S Pure Water Corp - California | Michael Alan Davis | — | (415) 883 9900 | Other | Novato · Marin County | — | — |
| Ubik Cabinetry & Fine Carpentry | Westlake Lawrence | — | (415) 798 4530 | GC, remodel, ADU | Mill Valley · Marin County | — | — |
| Unimax Construction | Dustin Ricardo Kudela | office@unimaxconstruction.com | (916) 308 0983 | GC, remodel, ADU | Novato · Marin County | — | — |
| Unique Land Construction | Carlos Alfonzo Castro | — | (707) 318 5246 | GC, remodel, ADU | San Rafael · Marin County | — | — |
| Unique Painting Services | Juan Carlos Hernandez-Vanzzini | — | (415) 635 1601 | Windows, patio, painters | Novato · Marin County | — | — |
| United Contractors | Patrick Musyoka Muithya | — | (415) 250 4787 | GC, remodel, ADU | San Rafael · Marin County | — | — |
| United V I Plumbing | United V I Plumbing | — | (415) 883 3900 | Other | Novato · Marin County | — | — |
| United Vi Plumbing INC | Ixmay Victor Vicente | — | (415) 320 9001 | Other | Novato · Marin County | — | — |
| Unlimited Construction | Ziai Alireza | unlimitedconstruction@mail.com | (415) 505 1127 | GC, remodel, ADU | San Rafael · Marin County | — | — |
| Upright Corporation | Lee Carlos Olibas | — | (650) 704 3904 | GC, remodel, ADU | Greenbrae · Marin County | — | — |
| Upscale Construction INC | Danny Joseph Bernardini | — | (415) 563 7550 | GC, remodel, ADU | San Rafael · Marin County | — | — |
| Urban Building Workshop INC | Kevin Michael Skiles | — | (415) 306 3431 | GC, remodel, ADU | Mill Valley · Marin County | — | — |
| Urban Crew Construction INC | Sarah Joanne Mccrystal | — | (415) 418 0471 | GC, remodel, ADU | Sausalito · Marin County | — | — |
| Urban Energy INC | Fergal Padraic Macdonnell | — | (415) 871 0395 | Electricians | San Rafael · Marin County | — | — |
| Urban Painting INC | Jeff | info@urbanco.com | (415) 302 6068 | GC, remodel, ADU | San Rafael · Marin County | — | — |
| Urban Waterproofing INC | Marshall O' Neil Johnson | info@urbanco.com | (415) 485 1134 | GC, remodel, ADU | San Rafael · Marin County | — | — |
| Urbano Painting Services | Manuel Francisco Paredes Rodriguez | — | (628) 238 9063 | Windows, patio, painters | San Rafael · Marin County | — | — |
| Utah Stsf LLC | Thomas Benjamin Casey | — | (415) 601 2369 | GC, remodel, ADU | Fairfax · Marin County | — | — |
| Utopia Property Management | Novato Ca | Utopia Property Management | Novato Ca | northbay@utopiamanagement.com | (707) 532-1111 | Property managers | Novato · Marin County | — | — |
| V L Kacer Construction | Kacer Lukas | — | (415) 305 6528 | GC, remodel, ADU | Novato · Marin County | — | — |
| V R H Drywall INC | Hernandez Viridiana Razo | — | (415) 755 7943 | Other | Novato · Marin County | — | — |
| V Reyes Tile & Stone | V Reyes Tile & Stone | — | (903) 268 3354 | Other | San Rafael · Marin County | — | — |
| V Studio INC | Vincent Lawrence Espinoza | — | (510) 846 0970 | Other | San Rafael · Marin County | — | — |
| Va Tile Concepts | Va Tile Concepts | — | (415) 314 3413 | Other | Novato · Marin County | — | — |