Shared Knowledge

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Images Courtesy of Dahlin Group Architecture Planning

Building information modeling (BIM) is a three-dimensional (3D) computer-generated model that can incorporate design, time, system and location data into a single file. BIM digitally captures the physical and functional characteristics of a building, such as a home, and how they interact. The model serves as the single, shared library for both 3D and 2D information about the building. Using this shared library, project team members can make informed decisions during the building’s life cycle, which is defined as existing from earliest conception to demolition.

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BIM enables a virtual information model to be handed from the design team to the contractor and subcontractors, then to the building’s owner. Each professional inputs discipline-specific information into the shared model. The extracted information helps architects, designers, builders and operators make more informed design and construction decisions that result in better end products.

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Who uses BIM?

BIM is an increasingly used tool that helps facilitate integrated project delivery (IPD), a collaborative approach to the design and building process. IPD harnesses the talents of many individuals to enhance coordination and maximize efficiencies, from product design through construction, thus increasing value to the owner and reducing errors and waste.

BIM is used by architects, engineers, contractors/builders, subcontractors, fabricators and property owners. The U.S. General Services Administration, U.S. Department of Defense, the state of Wisconsin, and other governmental agencies require the use of BIM because of recognized performance benefits that result from its use. In addition, BIM is also being used in Canada, the United Kingdom, Norway, France and India.

Why is BIM beneficial?

In standard practice, a design change can require modifications to multiple independently constructed drawings. This disassociation between drawings introduces more opportunities for errors. For example, an architect could update floor plans with a change but miss updating the elevation.

With BIM, opportunities for errors are reduced since a single change is applied across the project. If the width of ‘window type A’ needs to be increased by 6 inches, a team member can change one ‘window type A’ in the computer model and the change will automatically be reflected in all other places and drawings in which ‘window type A’ occurs.

Objects that relate to the object being modified also change as necessary. For example, when the width of ‘window type A’ is increased by 6 inches, the trim, shutters, wall assembly and flashing associated with each occurrence of window type A are updated accordingly.

How can BIM help home builders?

BIM can be used for visualization, fabrication/shop drawing generation, code reviews, facilities management, construction sequencing and trade coordination. Teams that use BIM view it as a reliable basis for decision-making and believe it reduces redundancies by being the sole coordination point for a project. It can facilitate better communication, collaboration and coordination among building industry professionals and trades working on a project, whether the project is a roadway, office building, high-rise, or single-family home.

By incorporating time and location data into the model, BIM allows for accurate analyses of energy use, lighting and acoustics before anything is built. BIM also accommodates specific data for appliances, fixtures and systems. For example, an air conditioning unit placed in a model can also contain data about its supplier, operation and maintenance procedures, flow rates and clearance requirements.

Since an entire building and its systems and lifecycle can be modeled, cost estimates and material takeoffs can be more accurate. BIM can also check for spatial conflicts, leading to fewer errors and change orders.

Overall, BIM allows for better collaboration, consistent drawings, accurate cost estimating, and spatial conflict and system clash detection. BIM can increase construction efficiency and decrease costs if the project team embraces the collaboration required to make BIM work to its fullest potential. Because of these attributes, BIM is now used for infrastructure as well as buildings.

How has the use of BIM evolved?

In fall 2016, NAHB’s Economics and Housing Policy Group conducted a survey on NAHB members’ familiarity and usage of BIM, a follow-up to NAHB’s 2014 Building Information Modeling Survey. The survey included data from 4,756 and 4,573 respondents in 2016 and 2014, respectively. See the accompanying tables for summary results.

In 2016, most respondents who are familiar with BIM also said that they do or would use BIM for computer-aided design and drafting (94 percent), reviewing 3D plans (89 percent), project collaboration (86 percent), product specification (86 percent), integrated project delivery (84 percent) and trade coordination (84 percent). Other uses include code review/code checking, automated generation of shop drawings and energy and thermal modeling.

Overall, BIM familiarity and usage has increased among builders and architects over the past couple of years. NAHB will continue to track its usage and prevalence in the home building industry. For additional information, visit nahb.org/BIMToolkit.

The original article, written by Alexandra Isham, was published in the Summer 2017 Issue of Best in American Living.

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