| IBBOTSONS POTATOES | — | — | — | Open → |
| ID Planning | Leeds | — | — | Open → |
| Igenica Ltd | Bainton | — | — | Open → |
| ignore | Selby | — | — | Open → |
| Imran Qayum | Leeds | — | — | Open → |
| Imran Qayum | Leeds | imran.qayum@hotmail.co.uk | — | Open → |
| Inova Homes Ltd | Bradford | — | Midge Gaunt Managing Director INOVA Homes Ltd m: 07846 869412 a: 3 Greenfield Avenue, Bradford West Yorkshire BD18 2HS e: inova-homes@mail.com | Open → |
| INTERFACE LTD | — | — | — | Open → |
| Interloft Conversions Ltd | Tadcaster | info@interloft.co.uk | — | Open → |
| Interloft Conversions Ltd | Tadcaster | — | — | Open → |
| Inventive Design Associates Ltd | Greater Manchester | nigel@inventiveda.com | — | Open → |
| IPS PENSION BUILDER | — | — | — | Open → |
| Ipswich Borough Council | Ipswich | — | 01473 432966 | Open → |
| Ipswich Borough Council | Ipswich | — | — | Open → |
| Iran Khalfry | Bradford | — | — | Open → |
| Iroko Carpentry & Joinery | Leeds | — | — | Open → |
| ISHBEL JEUKEN | — | — | — | Open → |
| Isle of Anglesey County Council | Anglesey | BuildingControl@ynysmon.gov.uk | 01248 752222 | Open → |
| Isle of Wight Council | Newport, Isle of Wight | — | 01983 823585 | Open → |
| Isle of Wight Fire & Rescue Service | Newport, Isle of Wight | — | 01983 823194 | Open → |
| Islington Council | — | — | — | Open → |
| Islington Council | Islington | — | — | Open → |
| ISMA ALMA | — | — | — | Open → |
| ISMA ALMAS | — | — | — | Open → |
| ISMA ALMAS | — | — | — | Open → |