Preparing ‘as-built’ drawings and models is certainly one of the most crucial requirements of any design-build project. These final sets of construction assets validates how the contractor built the structure including all the changes and modifications that were made in the process. The finalised drawings and models are passed on from the contractors to the building owners and property managers.
The set of as-built drawings and models, though underestimated and neglected, broadly serve a dual purpose. Firstly, the as-built drawings and models act as a guidebook to the AEC (architecture, engineering, and construction) firms that are contracted for renovation and refurbishment of an existing structure. So, the time, cost, and resources that would have been utilised during pre-renovation survey are saved. Secondly, they help owners and facilities managers to conveniently undertake maintenance and refurbishment activities besides helping them during emergency situations e.g. for rapid evacuation.
Whereas data-rich as-built 3D building information models have obvious benefits over 2D drawing sets, the decision to choose one over the other mainly involves factors, such as the scale of the project, owner’s preference, and the design-build teaming structure. The owners of relatively small building projects may prefer 2D as-built drawings of an existing building, prepared by a technician after collecting accurate data on site. On the contrary, large-scale design-build and renovation projects may require BIM-driven as-built 3D models.
Assuming that the project in question has not had a BIM model for the design process which is then updated during the as-built stage of the project, there are two typical ways of preparing as-built BIM models. Firstly, using the as-built drawings and other construction drawing sets as the starting point, 3D BIM models can be prepared using applications such as Autodesk Revit. The second method involves the Scan to BIM technique where point cloud data of the structures. This point cloud data is then converted into an intelligent BIM model using tools such as Cloudworx and Scan to BIM applications such as Revit.
The as-built drawings and BIM models serve as a comprehensive reference tool for owners and property managers. They benefit from these as-built drawings and models in the following ways:-
• The finalised as-built construction assets make future project planning, including renovations, extensions, and redevelopments, convenient and cost effective for the owners.
• Since the as-built drawings and BIM models contain complete details related to dimensions, fabrication, erection, elevations, sizing, materials, location, and mechanical/electrical/plumbing utilities, the owners can use this data and conveniently manage facilities within budget.
• The owners can use these as-built assets to resolve disputes regarding insurance claims. In case of a massive loss due to extreme disasters, the insurance company will require extensive documentation, including the as-built drawings and models to support your claims.
As the as-built drawings and models are prepared by combining the drawings/models of all the building services, the owners and property managers can schedule maintenance operations of the building’s MEP (M&E) systems in a timely manner.