In Plain English
Quick Answer
A smart 3D computer model of a building that stores all design, construction, and operational data in one place.
Definition
Definition
Building Information Modeling (BIM) is a digital process for creating and managing intelligent 3D models that contain geometric, functional, and data-rich information about a building or infrastructure project throughout its lifecycle. BIM enables coordination between design disciplines, clash detection before construction, quantity takeoff, scheduling (4D), and cost management (5D). The level of development (LOD) defines how detailed and reliable the model information is.
Context
Why It Matters in Bidding
BIM directly affects estimating accuracy by enabling model-based quantity takeoff and early clash detection that reduces field rework and change orders. On bids requiring BIM coordination, contractors must price modeling labor, software, and coordination meetings as real scope, and a low LOD can leave quantities unreliable for hard-bid pricing.
Example
Example
A GC's preconstruction team runs a 5D BIM takeoff on a hospital model to pull steel tonnage and ductwork quantities, then flags HVAC-versus-structure clashes during coordination so subs price clean routing instead of carrying field-fix contingencies.
See Also
Related Terms
Resources
Related Tools & Templates
FAQ
Questions Contractors Ask
Does a contract require BIM, and who pays for it?
When the specifications or a BIM execution plan mandate modeling, the cost of coordinators, software, and clash-detection meetings becomes biddable scope. Contractors should read division specs carefully, because assuming the design team owns all modeling can leave coordination labor uncovered and erode margin after award.
How does LOD affect using BIM for a takeoff?
Level of development signals how reliable model quantities are. A low LOD shows approximate geometry suitable for early budgeting only, while higher LOD supports detailed quantity extraction. Estimators must verify LOD before trusting model counts; pulling quantities from an underdeveloped model risks underbidding material.
Is BIM the same as a 3D CAD model?
No. A 3D CAD model is geometry only, while BIM embeds data such as material type, dimensions, and performance attributes into each element. That data layer is what lets estimators extract quantities, link costs, and detect conflicts, making BIM far more useful for preconstruction than visualization alone.
Need more than definitions?
Get AI-powered bid alerts, automated form filling, and proposal drafting.
Start Free Trial