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    BIM requirements: know enough to be dangerous

    Day in and day out we receive calls from General and Trade Contractors asking for help. They find themselves bidding a job or even having an awarded contract, where it is specified by the Owner that Building Information Modeling will be required for the Coordination process, Shop Drawings creation, As-Builts, or other. 

    Facility Owners are recognizing that BIM lowers their construction risk, eliminating waste and ultimately reducing their final cost. The US contracting industry has embraced the vision and this has turbocharged its adoption. If the job is larger than 5 million in total construction cost, there is a big chance you will have BIM requirements. Especially if the project is Institutional (Education, Healthcare, Religious, Labs,…), Government/Publicly Owned, and even Commercial (Hotels, Offices, Retail). Residential is still behind in adopting BIM modeling.

    Most of the times the BIM requirements can be found on the Specs, on Division 01 under the general conditions or in the Project Management or Coordination section.

    You may already have BIM experience and even a BIM Manager on staff, and then this may not be an issue for you and this article may contain obvious concepts. But if you do not, don’t worry, you can still bid for the job and you can still win it and do it successfully. But to be able to do so, you need to learn enough of the main BIM concepts and processes. Not only to be able to maintain a conversation with your prospect Client (GC or the owner) and give them confidence you will handle the job correctly, but also to know how to request a quote to a BIM services consultant and later manage its deliverables. To make sure you comply with the requirements so that BIM doesn’t become the reason of delaying construction and payments to you and ultimately so that you take advantage of the efficiencies that it can bring you.

    The intent of the article is to point you in the right direction quickly. BIM solutions cannot be learned overnight, and this article is here to summarize the main points.

    Of course, unless you have an in-house BIM team, you will need to hire a BIM services provider that will perform the actual modeling and perhaps even represent you on all BIM aspects before the client and the rest of the stakeholders.

    In most of the cases, these BIM requirements will only ask for 3D Coordination and As-Builts. This will typically imply having to create the BIM Model/s of the disciplines you are building (that may or may not state a specific software i.e: Autodesk REVIT, Bentley AECOsim), Coordination including Clash Detection, coordination meetings and clash resolution (that may also require specific software i.e: Autodesk Navisworks, Bentley Navigator etc…), and finally once model is signed off, the extraction of the layout/install drawings from the coordinated model.

    In some more sophisticated clients, you may see BIM for FM requirements or Lifecycle Building Information management. Referred to the data this models need to incorporate during the design and construction to hand over a data-rich Building Information Model. This requirement is less often yet, but we are seeing it more and more. Within it you may find a “COBie” requisite (Construction Operations Building information Exchange). Which is a standard on how the data has to be structured, organized and completed through the Design and construction phases. More on COBie at http://www.wbdg.org/resources/cobie.php

    Here are 7 things you need to know to have a successful outcome:

    First of all, you need to be involved in the process, even if you outsource the entire scope. As contractor, you will be held accountable for the Model/s, that must be a virtual representation on how you will build it in real life. You are the one that ultimately knows exactly how you will install, and that knowledge has to be incorporated into the Building Information Model. You need to be an active participant in the Spatial Coordination process, so the clashes are resolved incorporating the criteria you would use in the field to resolve them.

    Beware of the existence of a standard for the Level of Development called “LOD”, that was initially created by the American Institute of Architects AIA, and further develop by the BIM Forum. This LOD described the precision of geometry and information the model needs to include. Including what elements have to be represented in this model. If you are a trade contractor, most likely you will need to create LOD 350 or 400 models. Which is a Construction/Fabrication level model. This critical that you pass it along your BIM consultant as a delivery requirement, and ideally you list the elements you want them to include in the Model. A good example are the hangers. A design model, LOD 300 has no hangers and that is ok for a design model. But to have a real construction coordinated model, you need hangers to be there because the take space and have a significant impact on the coordination.

    You can learn about it on the BIM Forum Level of Development Specification http://bimforum.org/lod/

    BIM is not CAD. The overall purpose of traditional coordination and BIM coordination is the same. The ultimate goal is to get those Layout/Install Drawings so that the field guys can install. But the way to get there is different, with BIM the process is different. You will not see drawings right away, the center of attention is the model initially, it needs to be created first, go through that iterative clash detection/clash resolution/visual checks process until coordinated and then drawings can be extracted. The most important difference is that BIM is a collaborative process. During the 3D BIM coordination all the stakeholders must work together on the model, incorporating everyone’s criteria, to resolve the issues before going to the field. The drawings set up can be done lot earlier, and once Coordinated model is approved, drawings are ready to be dimensioned and tagged.  Bear in mind that these drawings are parametric 2D views of that 3D model, so you can do a significant amount of the work before the final model is signed off.

    What if a Design MEP Model exists? If designers provide, let’s say a REVIT MEP model and designers have performed a design coordination effort. It will definitely serve as a guide, and you can probably consider that the coordination process can be somewhat easier, because you can assume more has been thought through than if it would be just 2D CAD. But unfortunately, you will probably need to remodel. In real word it’s a nightmare trying to transform a designer’s model into a construction model. No fault of the designer, because it is not his scope. For example, consider that at design stage there are no material transmittals, so there are no specific fittings, and the models will be created with generic pieces. If you only take that in account, replacing all fittings is most of the times more work that creating a new model with the right fittings. Additionally, these actual manufacturers fittings may force changes in the layout.

    Who will be the “BIM Manager”? You need to find out who will take the BIM manager role, that includes gathering all other discipline models, combining the into a federated model, running clash detection, and then leading the weekly coordination meetings. This role is most of the cases from the GC, but we have seen many times the Mechanical Contractor taking this role, and in some cases even the architect or a BIM consultant hired directly by the owner, but this is more unusual. If you will take this role, you need to take it in account when you price the job, whether you do it internally or hiring a BIM consultant to do it on your behalf. If you are not going to be the BIM Manager, you need to still do your internal clash analysis among your own disciplines, and you will still be responsible of adjusting the model when modifications of your discipline are required.

    What is the requirement for Handover? Be careful on this aspect, because each owner is different, and the requirement can go from just 2D As-Built Drawings, As-Building the BIM you used for Coordination according to as constructed conditions, to delivering a Data-Rich BIM, which can include a full COBie delivery. Also, lately we have seen several projects requiring Laser Scanning the completed areas, taking the point cloud generated by this scanning and matching it with the BIM model geometry.

    Select the right BIM Partner. Price is obviously an important aspect, and I am not saying to ignore it, but do not make it your main selection criteria. BIM will not be just another requisite your need to comply with. We have seen many cases where clients hold payments, where construction is on hold because for example, model is not yet clash free, signed off and drawings cannot be extracted and signed off. So cheap may end up been very expensive. The right BIM partner is a company that has the experience and enough qualified manpower to move at the paste the project needs to.

    This document intent to give basic tips to those, especially Contractors and Subs that are not yet BIM experts but are starting to get BIM requirements or decided to move a step forward into adopting this technology.

    Also, the National BIM Standard – United States – Version 3, that can provide clarification on scope, roles and process: https://www.nationalbimstandard.org/

    Feel free to contact us for any question at 949-432-4204 or at axel.kruger@engbim.com.

    Axel Kruger - ENG
    Axel Kruger – ENG Founder & CEO

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