| Juneau Fed Building | Seattle | WA |
| Kadlec Hospital | Richland | WA |
| Kaiser Aluminum & Chemical | Seattle | WA |
| Kaiser Aluminum & Chemical | Vancouver | WA |
| Kaiser Aluminum & Chemical | Spokane | WA |
| Kaiser Aluminum & Chemical | Wenatchee | WA |
| Kaiser Aluminum & Chemical | Mead | WA |
| Kaiser Aluminum & Chemical | Tacoma | WA |
| Kaiser Cement & Gypsum | Seattle | WA |
| Kaiser Shipyard | Vancouver | WA |
| Kaiser Steel | Vancouver | WA |
| Kalama Chemical | Kalama | WA |
| Kenai Packers - Airedale & Labrador | Seattle | WA |
| Kenite | Quincy | WA |
| Kennecott Copper | Seattle | WA |
| Kent Junior High | Kent | WA |
| Kentucky Building | Tacoma | WA |
| Kerley Chemical | Finley | WA |
| Kerley Chemical | Spokane | WA |
| Ketchikan Pulp | Seattle | WA |
| Keyport Torpedo Station | Keyport | WA |
| Key Services | Tacoma | WA |
| Kicwit Massart | Olympia | WA |
| Kimberly & Clark | Everett | WA |
| King County Hospital | Seattle | WA |
| Kiro Broadcasting House | Seattle | WA |
| Kitsap Company Pud #1 | Port Orchard | WA |
| K J Barnett | Mercer Island | WA |
| K. J. Barnett | Renton | WA |
| KJ Barnett | Seattle | WA |
| Klickitat Pine Box | Goldendale | WA |
| Klug & Smith | Tacoma | WA |
| Kodiak Alaska | Seattle | WA |
| Kraft Bleach Plant | Camas | WA |
| Kraft Pulp Division | Tacoma | WA |
| Kula Gulf | Tacoma | WA |
| Lafayette Elementary School | Seattle | WA |
| Lake Hills Sewage Treatment Plant | Seattle | WA |
| Lakeland Village State Hospital | Medical Lake | WA |
| Lakeside Sand & Gravel | Issaquah | WA |
| Lake Union Shipyard | Seattle | WA |
| Lake Washington Shipyard | Seattle | WA |
| Lamb Western | Quincy | WA |
| Landreth Timber | Tonasket | WA |
| Larson Air Force Base | Moses Lake | WA |
| Larson Lumber | Bellingham | WA |
| Latona Elementary School | Seattle | WA |
| Latter Day Saints Church | Mount Vernon | WA |
| L.C. Smith Building | Seattle | WA |
| Learning Resource Center | Wenatchee | WA |
