| # | Company name | Role | # of projects |
|---|---|---|---|
| 1 | Z & H Engineering | Consultancy | 0 |
| 2 | Zajicek Engineering & Surveying | Consultancy | 0 |
| 3 | Zakalak Associates | Consultancy | 11 |
| 4 | Zavala County Couthouse | Consultancy | 0 |
| 5 | ZEF UK Ltd. | Consultancy | 0 |
| 6 | Zen Reprographics | Consultancy | 0 |
| 7 | Zenkner & Handel | Consultancy | 5 |
| 8 | Zentra Grundstücksgesellschaft mbH | Consultancy | 1 |
| 9 | Zeuthen og Sørensen | Consultancy | 1 |
| 10 | Ziona Strelitz Associates | Consultancy | 0 |
| 11 | Zoller Najjar & Shroyer Inc | Consultancy | 6 |
| 12 | Zook Moore & Associates | Consultancy | 1 |
| 13 | Zussman Bear Partnership | Consultancy | 0 |
| 14 | Zvi Hemly Engineers Ltd. | Consultancy | 52 |