The as-built model records the final state of a construction project and serves as a fundamental document for facility management, maintenance, and potential future renovations. Building Information Modeling (BIM) could assist in creating this from the very first minute, but if that didn’t happen, it can be refined retroactively using laser scanning and digital data collection methods. This article explains why an as-built model is necessary, how BIM relates to it, and what mistakes can be avoided.
In this article:
- What is an As-Built Plan?
- Why is an As-Built Model Necessary?
- The Importance of As-Built Models Often Only Becomes Apparent at the End of Construction
- Why Would BIM Be Ideal From Day One?
- If BIM Wasn’t Used From the Start, How Can It Help Retroactively?
- Why is the Use of As-Built BIM Models Becoming Increasingly Common?
What is an As-Built Plan?
An as-built plan is a collection of technical drawings and documentation that records the changes made during construction, reflecting the final completed facility.
Its Content:
- Geometric information: The exact locations of structures, doors, windows, and MEP (Mechanical, Electrical, and Plumbing) systems.
- Technical data: Installed materials, structural elements, manufacturers, and part numbers.
- Documentation: Permits, maintenance manuals, and technical specifications.
Its Format:
- Traditional: 2D drawings or paper-based documentation.
- Modern version: BIM-based digital models.
Why is an As-Built Model Necessary?
Throughout a building’s lifecycle, facility management and maintenance can only be efficient if accurate and up-to-date data is available—something an as-built BIM model provides. Continuously and accurately tracking the actual condition of the building is crucial for optimizing operational processes, planning maintenance in advance, and accurately executing potential renovations. A well-documented as-built model ensures that every element of the building—structural components, MEP systems, and materials—can be precisely identified and tracked, thus avoiding information gaps during operation.
Regulatory requirements also dictate the importance of the as-built model. In Hungary, Government Decree 191/2009 (IX. 15.) mandates that if deviations from the original plans occurred during construction, the preparation of an as-built plan is compulsory and must be uploaded to the electronic construction log (e-napló). This ensures that authorities and facility managers receive an accurate picture of the building’s true state, which is essential for transparency and legal compliance.
Future modifications and renovations also require the existence of accurate documentation. If the building is expanded or undergoes internal structural alterations, architectural and engineering design can become exceedingly difficult without a well-structured as-built model. Missing data makes the construction process slower, more expensive, and far riskier, as unforeseen problems can arise without precise knowledge of the building’s structural characteristics.
An accurate as-built model also plays a key role in clarifying warranty and liability issues; without it, tracing the origin of potential defects becomes significantly harder. If a problem arises in the building later—for example, a built-in system fails or a structural issue emerges—the model allows professionals to trace exactly what was built, how it was built, and with what materials. This makes life easier not only for contractors and facility managers but also for investors and property owners, as liability questions become much clearer and better documented.
Therefore, an as-built model is not merely an administrative obligation or piece of construction documentation. It is an operational and strategic tool that ensures efficient operation, transparency, and long-term sustainability throughout the building’s entire lifecycle.
The Importance of As-Built Models Often Only Becomes Apparent at the End of Construction
Many contractors and investors only realize they need an as-built model at the very end of the project. It frequently happens that modifications made during construction are not properly documented, meaning the actual state deviates from the original plans. Consequently, upon building handover or the start of operations, the crucial data required for efficient maintenance and future modifications is missing.
This late realization can have several severe consequences. One of the biggest problems is retroactive reverse-engineering, where changes that were omitted or poorly recorded during construction must be reconstructed. This is an extremely time-consuming and costly process, requiring professionals to conduct separate on-site surveys, which can delay or complicate facility management.
Inaccurate or unsearchable information poses another issue. If the exact parameters of a given structural element or MEP system are unavailable, it will cause problems during operation and maintenance. Due to a faulty or undocumented installation, future alterations can become more expensive and riskier; without precise technical data, demolition or extra work may be required.
All of this could be avoided if the as-built model were continuously updated during construction. BIM-based solutions allow every modification to be recorded in real time, so upon handover, the model accurately reflects the finished building’s state and can be utilized effectively in later operational processes.
Why Would BIM Be Ideal From Day One?
One of the biggest advantages of BIM is that information generated during the construction process can be recorded immediately and updated continuously. Thanks to this, the as-built model does not become a retroactive, time-consuming documentation task, but develops organically as an integral part of construction.
If BIM is applied right from the design phase, changes and modifications can be tracked in real time and are automatically incorporated into the model. This means that modifications arising during construction can be tracked with minimal effort by adjusting the existing design model. Thus, the final model always reflects the current state, and at the end of construction, updated plan documentation can be generated based on this actual state.
Fewer Errors and More Cost-Effective Construction Through Clash Detection One of BIM’s key functions is clash detection, which enables the coordination of architectural, mechanical, and electrical system plans long before construction begins. Thanks to this, errors and conflicts that typically surface during execution—such as an improperly planned HVAC duct or a structural element blocking an electrical cable pathway—can be filtered out during the design phase. Identifying and correcting these clashes before breaking ground leads to significant time and cost savings by preventing retroactive modifications, eliminating the need for redesigns, and minimizing material waste and schedule delays.
A Shared Database and Accurate Documentation for Transparency Another benefit of BIM-based design and construction is that project participants work from a common database, where all necessary information is available up-to-date and in a standardized format. In traditional documentation systems, information is often fragmented across different files and platforms, leading to communication errors, data loss, and misunderstandings. In contrast, BIM stores all relevant data in a central digital system, ensuring that all stakeholders—designers, contractors, and facility managers—see and use the same information. This guarantees transparency throughout the construction process, reduces the risk of human error, and significantly improves project management efficiency.
BIM-Based As-Built Models Support Facility Management and Maintenance A BIM-based as-built model contains not only the building’s spatial data but also detailed information about materials, structural elements, and installed systems. This is particularly important for building operation and maintenance, as the BIM model enables the optimization of energy consumption, the advance planning of maintenance work, and the reduction of operational costs. The detailed and structured data provided by BIM ensures that reliable, up-to-date information is available at every stage of the building’s lifecycle, supporting efficient and sustainable operations.
If BIM Wasn’t Used From the Start, How Can It Help Retroactively?
If BIM was not utilized at the beginning of a construction project, creating an as-built model can still be achieved later through various data collection and digitalization methods. Recording the building’s actual condition is crucial for facility management and maintenance, as the resulting digital model accurately maps the building’s true geometry, materials, and structural elements. Several technologies are available for constructing a retroactive BIM model, depending on the type of documentation available and the required level of precision.
- Laser Scanning During Construction (LIDAR): Laser scanning allows for the rapid and precise digitalization of a building. From the point cloud generated by laser beams, a 3D BIM model can be created that reflects the existing state. This is especially useful if changes occurred during construction or if accurate documentation of the building is missing. This method is extremely precise and fast, minimizing manual measurement errors and providing a reliable foundation for facility management.
- Digitizing and Integrating Existing 2D Documentation into BIM: If only 2D blueprints were created during construction, they can be transformed into a BIM model. Original paper-based or digital plan files are converted into BIM software and then supplemented with on-site surveys. This solution enables existing plans to be brought up to date and integrated into the facility management system in digital form. It is a quick and cost-effective solution when the necessary documents are available.
- Other Photo-Based Data Collection Methods: If neither accurate plan documentation nor laser scanning is an option, photogrammetry and drone photography can also assist in digitizing the building. Based on high-resolution images, a 3D model can be built that visually documents the building’s condition. While less precise than laser scanning, this method can be a cost-effective solution for condition assessments or digitizing hard-to-reach areas.
Retroactive BIM modeling can help make up for missed digitalization efforts, ensuring the building’s actual state is precisely recorded for facility management and maintenance.
Why is the Use of As-Built BIM Models Becoming Increasingly Common?
For investors, the facility management model is one of the most vital tools for managing a building’s entire lifecycle, as it ensures transparent and efficient operation while helping to optimize operational costs. However, the success of facility management heavily depends on the database it is built upon. Consequently, a growing number of stakeholders are realizing that an accurate, up-to-date as-built BIM model is indispensable for supporting operational processes.
The as-built BIM model forms the foundation of the facility management model by recording the modifications executed during construction, along with the actually installed materials, structures, and systems. Because of this, facility management is based on real data, rather than potentially outdated or inaccurate information from the design phase. Increasingly, investors expect not just an as-built plan during construction, but a comprehensive, digital BIM model that can be utilized directly in facility management systems. This enables the precise tracking of MEP, electrical, and structural elements, and provides a solid basis for maintenance and development decisions.
A BIM-based as-built model is therefore not simply construction documentation; it is the cornerstone of facility management. A well-prepared as-built BIM model guarantees that the building can be easily sustained, operated, and maintained over the long term, all while helping reduce operating costs and increase sustainability. As a result, the use of digital building models is rapidly becoming a baseline requirement, as accurate and structured data is essential for efficient property management and long-term investment protection.
We Can Help You Create BIM-Based Digital Models
Whether you need an as-built model or BIM-based documentation, our team is ready to help. If you want an accurate, up-to-date as-built model that supports facility management, maintenance, and future developments, contact us and discover how you can make your projects more efficient by applying BIM!
