Whether a BIM model is considered a Contract Document required to be followed is a matter for agreement among the project participants. Depending on how the parties agree on the protocols for and the extent of permissible reliance on shared BIM in constructing a project, BIM models can run the gamut from serving as a check on accuracy of traditional 2D plans to replacing those plans as the official project drawings, or anything in between. The AIA’s newly released E201-2022, for use when at least some BIM version will become a Contract Document, and E202-2022, for use when that will not be the case, facilitate establishing these protocols.
Whether reliance on BIM models is proper ought not be left to interpretation, and the E201-2022 and E202-2022 strive to ensure that it is not, confining permissible reliance to designated uses, beyond which any reliance will be at the user’s own risk. In the absence of agreement on the point, ordinary contract principles will determine whether a party’s reliance on a BIM model furnished by the other party is reasonable. In general, reliance on information provided by one party to the other for use in his contract performance will, in the absence of a disclaimer, be deemed justified. In such a case, errors in the BIM or undisclosed changes to the BIM can come back to haunt the provider.
Sometimes actual field conditions differ from what was expected based on the BIM, and a clash not modeled is nevertheless encountered during installation. Adjustments made in the field to accommodate those differences can spawn what look very much like Type I differing site condition claims. And if the finished product does not perform as expected, those same field adjustments can take on all the trappings of a dispute over whether a design defect or a construction defect is present. Ideally, any disparity between what was modeled and what was encountered should be promptly raised with the architect or owner’s rep for instruction and potential redesign, implementing the change order process if the BIM is a Contract Document. But in the heat of battle, such command decisions are not always made at the highest levels; installers encountering something that, per the BIM, should not have been in their way often simply work around it and move on. That can have ripple effects for the next trades working on the project.
While the BIM may demonstrate how the plumbing, HVAC, electrical and anything else can all fit in a given space without clashes, the tighter the space the more important each trade’s means and methods will become in order to make it all fit. Coordination and sequencing of trades is key here; the last trade to perform, who must work around prior trades’ work, will need a different plan of attack than the first trade in. If the work sequence is altered after a contractor’s or subcontractor’s reliance on a time-simulated 4D BIM showing no obstructions to its work, the financial consequences of dealing with unanticipated obstructions can be huge. For a cautionary tale, North American Mechanical Inc. v. Walsh Construction Company II LLC, 132 F.Supp.3d 1064 (E.D.Wis. 2015), is worth a read.