1.2 The Problem BIM Solves in Construction

Introduction

BIM is often defined as a process for creating, managing, and exchanging information about a built asset throughout its lifecycle. That definition raises an obvious question. Why did construction need a new process at all?

The answer is not really about technology. It is about how information moved, or failed to move, between the people working on the same project.

How Construction Worked Before BIM

For most of the industry's history, a project existed as a stack of separate 2D drawings. The architect kept one set. The structural engineer kept another. Mechanical, electrical, and plumbing consultants each kept their own. These drawings described the same building from different angles, but they were rarely, if ever, checked against each other automatically.

There was no single source of truth. The same piece of information, a wall's location, a beam's size, a room's ceiling height, could exist in four or five different drawings, updated by four or five different people, on four or five different schedules. If one person changed a detail and forgot to tell everyone else, the drawings simply disagreed with each other and nobody knew until it mattered.

Coordination depended almost entirely on people. Someone had to lay drawings over each other, by hand or by eye, and manually spot where a duct ran through a beam that was not supposed to be there, or where a door swung into a wall that had since moved. This worked, up to a point, but it did not scale well as projects grew larger and more complex.

In 2004, the National Institute of Standards and Technology in the US studied exactly this problem. Their research found that inadequate interoperability, meaning the inability of different software and information systems to work together properly, was costing the US capital facilities industry an estimated $15.8 billion every year. Owners and operators carried the largest share of that cost, largely from re-entering and reconciling the same information across systems that could not talk to each other.

The Core Problems This Created

Fragmented information created a predictable pattern of failure. A clash between two building systems, say a structural beam and a mechanical duct occupying the same space, would go unnoticed on paper and get discovered on site, usually by whichever trade arrived second. At that point it was no longer a drawing problem. It was a demolition and rebuild problem.

This kind of rework is expensive, and it has been measured repeatedly. The Construction Industry Institute has found that direct field rework averages around 5 percent of total project cost, with individual projects ranging anywhere from 2 to 20 percent depending on how the work is delivered and tracked. A separate 2018 study by PlanGrid and FMI, surveying nearly 600 construction professionals, tied more than $31 billion a year in US rework specifically to poor communication and missing or incorrect project information, responsible for roughly half of all rework recorded.

Timing made the problem worse. There is a well known idea in construction called the MacLeamy Curve, first drawn by architect Patrick MacLeamy in 2004. It shows a simple but important relationship: the cost of changing a design increases sharply the later that change happens, while the ability of that change to actually improve the outcome decreases at the same time. A wall moved on paper during design costs almost nothing. The same wall moved after the concrete has been poured costs a great deal, in money, time, and trust between everyone involved.

Put simply, the traditional workflow tended to find its mistakes at the most expensive possible moment.

What BIM Changed

BIM did not eliminate errors. What it changed was where and when those errors got found.

Instead of separate 2D drawings maintained independently, BIM centers the project around a coordinated model, or set of coordinated models, carrying consistent information that every discipline works from and checks against. A clash between a beam and a duct can be seen on screen during design, while it still costs almost nothing to fix, rather than on site, once it costs a great deal.

This idea was significant enough that the UK Government built an entire construction strategy around it. In 2011, it required fully collaborative 3D BIM on all centrally procured public projects by April 2016, a requirement later known as BIM Level 2. The government's own Construction 2025 strategy, published in 2013, set out what it expected this shift to achieve: a 33 percent reduction in construction and whole-life costs, and a 50 percent reduction in delivery time, alongside targets for lower emissions and a smaller trade gap. It is worth being honest that later reporting found the industry fell short of most of these specific numbers. But the direction of travel was real. Industry survey data has consistently shown that firms using BIM report genuine coordination benefits. NBS's 2020 National BIM Report found that 85 percent of BIM users said it increased coordination of construction documents, and 72 percent said it reduced the risk of problems arising during construction.

None of this means a coordinated model is automatically correct. It only means the model gives everyone a shared, current picture to check problems against, instead of a pile of drawings that quietly disagreed with each other. Whether the information inside that model is actually reliable is a separate question, and it is one this series will return to directly.