M&E services are more fragmented than architectural and structural disciplines. There is a two-tier design system in place. The MEP design contractor, also known as the MEP Designer Engineer, and the MEP contractor are the two key players in an MEP services project. 

This includes trade sub-contractors. MEP contractors and MEP design professionals have different responsibilities. 

The ideal situation is that the MEP Engineering Firm still develops the MEP design, while the contractor assumes the role of spatial coordination. This can be thought of as a detailed design in certain respects.

M&E BIM and conventional MEP CAD drafting methods, the design consultant receive both the architectural and structural drawings/models from each party during his design tenure. 

The industry's nature of the design means that multiple versions will be sent to the engineer while he continues with his design. 

Although the design intent is meant to work (spatially) with the structural and architectural drawings/models, the MEP consultant's drawings will not be sufficient detail to permit installation due to financial constraints and time constraints. The pre-fabrication details and the installation details. 

The MEP (M&E contractor) will use his/her technical product data and other data to create a service model that is conflict-free and allows for efficient installation, fabrication, and post-installation access.

MEP contractors will have MEP prefabrication drawings and layouts. These models/drawings will be sufficient to coordinate services within the allocated space. They will also prefabricate racks, modules, and assemblies inefficient runs and perform the installation without any on-field rework. MEP contractors will sometimes alter consultant-issued drawings to achieve this.