Level of Accuracy is one of those vague terms that is often thrown around without any real consideration being given to what it means or how to achieve it. Defining accuracy can be complicated which is why most clients don’t know how to specify it properly. Since there are a number of approaches one can take to document a building, it is very important for the client to have a good accuracy specification so the desired outcome can be achieved without paying for more than is really necessary. It is also important for the service provider so there are no unmet expectations which could result in re-work or other liabilities.
For example, if a client asks for ¼” accuracy what does he/she really mean? Is that a relative accuracy or an absolute accuracy? Without it being specified one bidder may interpret it one way and the other bidder may interpret it another way. Both could be justified in their interpretation, yet the outcome of their work could be very different. If the client goes with the low bid which was based on the low bidder interpreting the accuracy specified allowing for a lower cost process, both parties could find themselves in an unpleasant situation when they both discover the true expectation wasn’t met.
A poorly specified Level of Development can have similar implications. There are many variables when it comes to representing the measured data. When the deliverables take on the form of a 3D model the number of variables increases greatly. How will the out-of-plumb conditions be represented with a modeling tool that prefers to work orthogonally? If an LOD 300 or greater is specified that means concealed assemblies must be defined and represented. If laser scanning is used to capture the existing conditions, how will the information about what is inside the wall or roof assembly be determined? Do custom families need to be created that are parametric or can modeled in place elements be used? These decisions can have significant time and cost implications.
As noted, to reduce our risk when dealing with a poorly defined LOA or LOD, ARC has decided to incorporate the USIBD’s LOA Specification and the BIM Forum’s LOD specification directly into our proposals. If we are in a bid situation, we can specify exactly what it is that we are going to provide. If that means an interpretation of accuracy that results in a lower cost process, at least we’ve been clear and have something to point to other than a bunch of verbal hand waiving. If we quote a higher cost process because we believe that is what is required to meet the client’s intent, then we’ve given the client a means to vet out the other proposals he/she receives and hold them to the same standard.
As service providers we should take the lead on educating our clients on tools that are available for specifying services such as the USIBD’s LOA and the BIM Forum’s LOD. When the client doesn’t provide a proper spec, then we should provide clarity in our proposals with the same. In the end, the goal is to meet both the needs of the project and the expectations of the client, reduce our risk and hopefully have a profitable project and happy client.
