Quantity Take-offs from BIM Models


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As the Building Information Model has the information about all the objects in the building & their dimensions the quantity take-off to a great extent can be speeded up. BIM by itself not enable automatic take-off as the estimating process is more complex than simply getting a list of objects and their sizes. It also enables analyzing the building design, grouping objects into appropriate assemblies for construction, setting assembly and item variables, and then pricing the objects by taking off these assemblies or items. Thus, unless the BIM model was developed such that the objects are derived directly from construction assemblies, the assembly takeoff is still a substantial process in cost estimating. Currently, however, BIM applications do not model construction assembly details, for example, the nails, studs, drywalls, etc. for a wall object.

Tekla Structures is the first completely integrated 3-D solution for precast concrete. Modeling tools, such as automated and intelligent parametric adjustments, have been added to the software, while enhanced intelligence and modeling automation

For precasters, immediate benefits are realized in the reduction of casting and construction errors; rapid quantity takeoffs; and fast, accurate and consistent drawing creation. Other precasters using the Tekla system include High Concrete Structures, Blakslee Prestress and Coreslab Structures.

It also helps to create stair geometry and brick pattern with the architect. It also was used to solve lift-hook and erection issues with the precaster. All shop drawings and erection layouts were created with and maintained in Tekla Structures.

3D models have become regular process for industrial facilities like power plants, chemical plants or refineries. The clash detection capabilities help reduces costly interferences during construction, providing significant cost and time savings. The 3D modeling also provides more precise information to subcontractors to allow for better understanding of the scope of the project and more accurate bidding of construction. Owners and designers also are able to better visualize the spaces around equipment to ensure maintenance access requirements are met.