| Jr's Plumbing & Drain | Cedric William Johnson | — | (707) 373 2003 | Other | American Canyon · Napa County | — | — |
| Jre Heating And Air | Jre Heating And Air | — | (707) 287 2457 | HVAC | Napa · Napa County | — | — |
| Js Construction Services | Jacob John Songer | — | (707) 477 8946 | GC, remodel, ADU | Napa · Napa County | — | — |
| Judy Schindler Design & Build INC | Brian Rhodes Dodd | — | (707) 257 2815 | GC, remodel, ADU | Napa · Napa County | — | — |
| Jvc Steel | Jvc Steel | jcv@jvcsteel.com | (510) 447 9255 | Other | American Canyon · Napa County | — | — |
| Jvg Cooling & Heating Solutions LLC | Jesus Victor Garcia Ceballos | — | (707) 332 8188 | HVAC | Napa · Napa County | — | — |
| Jws Fire Protection | Jws Fire Protection | — | (707) 337 7971 | Other | American Canyon · Napa County | — | — |
| K B Diversified | K B Diversified | — | (707) 260 4034 | Electricians | Napa · Napa County | — | — |
| K G B Kirk Geyer Built | Kirk Richard Geyer | — | (707) 337 3025 | GC, remodel, ADU | Napa · Napa County | — | — |
| K M R Builders INC | Kevin Michael Roche | kevin@kmrbuilders.com | (707) 815 8077 | GC, remodel, ADU | Napa · Napa County | — | — |
| K Trekkor Wills Tile | K Trekkor Wills Tile | — | (707) 321 3234 | Other | Napa · Napa County | — | — |
| K V Construction | Kirt Thomas Vsetecka | — | (916) 996 0598 | GC, remodel, ADU | Napa · Napa County | — | — |
| K&s Asphalt Solutions INC DBA K&s Asphalt Sealing Solutions | Jessica Lizet Kite | — | (707) 307 9240 | Other | Napa · Napa County | — | — |
| Ka Construction INC | Kurtis Andrew Andersen | — | (707) 227 6259 | GC, remodel, ADU | Napa · Napa County | — | — |
| Kaiser Construction INC | Alan Maurice Kaiser | — | (707) 478 9782 | GC, remodel, ADU | St Helena · Napa County | — | — |
| Kanfoush Custom Concrete | Kanfoush Custom Concrete | — | (415) 741 4437 | Other | Napa · Napa County | — | — |
| Kashani Construction Company | Amir Mirza Kashani | — | (707) 287 4323 | GC, remodel, ADU | Napa · Napa County | — | — |
| Kaufman Building & Management INC | Jeffrey Alan Kaufman | — | (707) 732 3770 | GC, remodel, ADU | Napa · Napa County | — | — |
| Kb Construction And Design LLC | Kathleen Bennett | — | (208) 720 0007 | GC, remodel, ADU | Calistoga · Napa County | — | — |
| Kellebrew Construction Services | Donald Carl Kellebrew | — | (707) 363 6339 | GC, remodel, ADU | Napa · Napa County | — | — |
| Kelley Construction INC | Richard Elvis Kelley | — | (707) 302 5959 | GC, remodel, ADU | Napa · Napa County | — | — |
| Kelly Construction Co | Gerard Joseph Kelly | — | (650) 922 0210 | GC, remodel, ADU | Napa · Napa County | — | — |
| Kelly's Tree Service INC | Kelly Eugene Burr | — | (707) 363 0038 | Tree | Napa · Napa County | — | — |
| Ken Johns Plumbing | Ken Johns Plumbing | — | (707) 252 3582 | Other | Napa · Napa County | — | — |
| Ken Mays Plumbing INC | Raymond Montgomery Welch | maysplumbing@att.net | (707) 226 9232 | Other | Napa · Napa County | — | — |
| Kennedy Construction | David Ray Kennedy | rekconst@gmail.com | (707) 257 3267 | GC, remodel, ADU | Napa · Napa County | — | — |
| Kent Drescher Builder INC | Kent Steven Drescher | — | (707) 942 2234 | GC, remodel, ADU | Calistoga · Napa County | — | — |
| Kevin M Ahtty General Contractor | Kevin M Ahtty General Contractor | — | (707) 337 3954 | GC, remodel, ADU | Napa · Napa County | — | — |
| Keystone Woodworking | Victor Manuel Martinez | victor@keystonewoodworking.com | (707) 254 1955 | GC, remodel, ADU | Napa · Napa County | — | — |
| Keystone Yards | Owen Lynn | — | (415) 535 4856 | GC, remodel, ADU | Napa · Napa County | — | — |
| King Compactor Services | Oscar Ignacio Salas | — | (707) 266 1478 | Other | Napa · Napa County | — | — |
| Kirk De Alba Construction | Kirk Alan De Alba | — | (707) 479 3602 | GC, remodel, ADU | St Helena · Napa County | — | — |
| Kitfield Carpentry LLC | Scott Kitfield | — | (513) 616 5774 | Other | Napa · Napa County | — | — |
| Klimenko Construction | Peter Christopher Klimen | — | (510) 928 1359 | GC, remodel, ADU | Napa · Napa County | — | — |
| Klingbeil Plumbing | Klingbeil Plumbing | — | (707) 290 0063 | GC, remodel, ADU | Angwin · Napa County | — | — |
| Klopka Enterprises | Michael Otto Klopka | — | (610) 400 6601 | GC, remodel, ADU | Calistoga · Napa County | — | — |
| Knittel Construction INC | Gregory Scott Knittel | — | (707) 259 0321 | GC, remodel, ADU | Napa · Napa County | — | — |
| Knm Properties Inc. | Knm Properties Inc. | — | (707) 335-8700 | Property managers | Napa · Napa County | — | — |
| Korte's Backhoe Service | David Hubert Korte | — | (707) 942 0233 | Other | Calistoga · Napa County | — | — |
| Krueger Bros Builders INC | David Mendenhall Krueger | — | (707) 252 6688 | GC, remodel, ADU | Napa · Napa County | — | — |