| Westco Glass & Door INC | Eddy August Deniz | — | (707) 217 9341 | Windows, patio, painters | Rohnert Park · Sonoma County | — | — |
| Westech Roofing | Laurin Robert Hunt | — | (510) 719 0317 | Other roofers | Petaluma · Sonoma County | — | — |
| Western Builders | Cantu Robert | — | (707) 542 3213 | GC, remodel, ADU | Santa Rosa · Sonoma County | — | — |
| Western Built | Western Built | — | (707) 888 9565 | GC, remodel, ADU | Santa Rosa · Sonoma County | — | — |
| Western Construction Enterprises INC | Michael James Sr Hammer | — | (707) 544 0100 | Other | Rohnert Park · Sonoma County | — | — |
| Western Fiberglass INC | Michael Edward Lewis | — | (707) 523 2050 | Tree | Santa Rosa · Sonoma County | — | — |
| Western Floor Service INC | Bruce Konda Adams | — | (707) 938 9024 | Other | Sonoma · Sonoma County | — | — |
| Western Hills Construction | Garry Dee Elliott | — | (707) 874 1298 | Electricians | Sebastopol · Sonoma County | — | — |
| Western Water Constructors INC DBA Western Water | Roger Kenneth Kreischer | — | (707) 540 9640 | Other | Santa Rosa · Sonoma County | — | — |
| Westfall Construction | Blaine Patrick Westfall | — | (707) 235 3757 | GC, remodel, ADU | Fulton · Sonoma County | — | — |
| Westpac Construction | Adam Nathaniel Felix | — | (707) 806 9370 | Other | Healdsburg · Sonoma County | — | — |
| Westshores Construction | Carlos Alfredo Santos Estrada | — | (415) 336 1296 | GC, remodel, ADU | Rohnert Park · Sonoma County | — | — |
| Westside Mechanical Incorporated | Bruce Reinhold Fleischmann | — | (707) 795 9606 | HVAC | Cotati · Sonoma County | — | — |
| Westwood Builders | Martha Stella Evans | — | (707) 888 8099 | GC, remodel, ADU | Sonoma · Sonoma County | — | — |
| Wge Electric | Nathan George Ballou | — | (707) 490 2595 | Electricians | Petaluma · Sonoma County | — | — |
| Whalen Flooring | Whalen Flooring | whalenflooring@gmail.com | (707) 393 0080 | Other | Sebastopol · Sonoma County | — | — |
| Wharton Building | Wharton Building | — | (415) 933 7316 | GC, remodel, ADU | Petaluma · Sonoma County | — | — |
| White Grape Painting INC | Landeros Armando | whitegrapepainting@gmaill.com | (707) 570 9762 | Windows, patio, painters | Sonoma · Sonoma County | — | — |
| Whitfield Construction | Robert Michael Whitfield | — | (707) 888 4367 | GC, remodel, ADU | Santa Rosa · Sonoma County | — | — |
| Whiting Construction | Jack Joseph Whiting | — | (707) 478 2624 | GC, remodel, ADU | Santa Rosa · Sonoma County | — | — |
| Whs Appliance Installations | Whs Appliance Installations | — | (707) 332 1146 | Other | Sebastopol · Sonoma County | — | — |
| Wib & Associates INC | William Irvin Baker | — | (925) 575 0110 | GC, remodel, ADU | Santa Rosa · Sonoma County | — | — |
| Wiegner Construction Company | Terence Vaughan Wiegner | — | (707) 393 0330 | GC, remodel, ADU | Santa Rosa · Sonoma County | — | — |
| Wielder Construction INC | Stephan David Mosier | wielderconstruction@gmail.com | (707) 400 8353 | GC, remodel, ADU | Sebastopol · Sonoma County | — | — |
| Wiggins Electric INC | Dean Allen Wiggins | — | (707) 545 7869 | Electricians | Santa Rosa · Sonoma County | — | — |
| Wights Construction | Dale Melvin Wights | — | (707) 975 4837 | Other | Santa Rosa · Sonoma County | — | — |
| Wikiup Design & Construction | Carlos M Guevara | — | (707) 321 0591 | GC, remodel, ADU | Santa Rosa · Sonoma County | — | — |
| Wild Earth Art | Kelsi Maureen Anderson | — | (707) 217 5634 | Windows, patio, painters | Sebastopol · Sonoma County | — | — |
| Wildcat Engineering | Chad Eric Aanenson | — | (707) 762 5500 | Other | Petaluma · Sonoma County | — | — |
| Wildfire Tree Services | Gary Phillip Warner | — | (707) 401 0773 | Tree | Windsor · Sonoma County | — | — |
| Wildland Overwatch Remodeling | Geoffrey Spencer Eich | — | (805) 410 0122 | GC, remodel, ADU | Santa Rosa Valley · Sonoma County | — | — |
| Wildman Farms Landscaping | Wildman Farms Landscaping | — | (707) 321 8120 | Windows, patio, painters | Santa Rosa · Sonoma County | — | — |
| Wiljen INC DBA Valley Builders | John Garrick Desbiens | — | (707) 889 3775 | GC, remodel, ADU | Santa Rosa · Sonoma County | — | — |
| Will Will Construction Corp | Wilfrido Francisco Sanchez Pasos | — | (415) 246 6513 | GC, remodel, ADU | Petaluma · Sonoma County | — | — |
| Willems Construction | Andrew Dirk Willems | — | (707) 321 6355 | GC, remodel, ADU | Santa Rosa · Sonoma County | — | — |
| William Albright | William Albright | — | (707) 858 9613 | GC, remodel, ADU | Sebastopol · Sonoma County | — | — |
| William Botieff Contractor | William Botieff Contractor | — | (707) 343 7366 | GC, remodel, ADU | Sonoma · Sonoma County | — | — |
| William C Fethon | William C Fethon | — | (707) 484 7716 | GC, remodel, ADU | Forestville · Sonoma County | — | — |
| William C Johnson | William C Johnson | — | (707) 889 3678 | Windows, patio, painters | Santa Rosa · Sonoma County | — | — |
| William Cutler Flooring | William Charles Ii Cutler | — | (707) 529 0084 | Other | Sebastopol · Sonoma County | — | — |