| # | Company name | Role | # of projects |
|---|---|---|---|
| 1 | K & S Automatic Spklrs Inc | Fire protection engineering | 1 |
| 2 | Karina Design, Consultancy and Training Service Co. Ltd. | Fire protection engineering | 1 |
| 3 | Kaufman Fire Protection Systems | Fire protection engineering | 0 |
| 4 | Keene Fire Protection | Fire protection engineering | 1 |
| 5 | Kelly-son & Assoc | Fire protection engineering | 1 |
| 6 | Kennedy Mechanical Plumbing & Heating Inc | Fire protection engineering | 5 |
| 7 | Kersken & Kirchner GmbH | Fire protection engineering | 7 |
| 8 | Key Fire Protection and Piping Co. | Fire protection engineering | 0 |
| 9 | King & Co. Inc. | Fire protection engineering | 1 |
| 10 | KK-Palokonsultti Oy | Fire protection engineering | 9 |
| 11 | Knight Fire Protection | Fire protection engineering | 1 |
| 12 | Kolde Engineering Inc. | Fire protection engineering | 0 |