Expert article
BIM during construction: the model arrives on site
In design, BIM has arrived. The construction phase decides whether the model becomes a working tool or a file that nobody opens.
Expert article by Open Experience GmbH. · As of: September 2026
What does BIM deliver during construction?
On site, the BIM model delivers three things above all: a ready-made project structure, because storeys, rooms and building elements can be taken straight from the IFC file; precise positioning, because a defect hangs on a building element and a 3D coordinate instead of on a description of where it is; and a lossless exchange with the design team through the BCF format. What it does not deliver is the actual condition — that comes only from capture on site.
Legal framework: Germany (Civil Code BGB, construction contract rules VOB/B, fee schedule HOAI). Other countries have different rules, and contractual agreements take precedence over the standard periods named here.
The project structure comes out of the model
The first practical benefit has little to do with 3D. Every documentation system needs a structure — construction section, storey, apartment, room, building element. Creating that structure by hand costs days and produces deviations from the design. From an IFC file it can be exported, at whatever level of detail you want.
- Choose the level of detailDown to the storey, down to the room or down to the individual building element — depending on how precisely you want to position things later.
- Adjustable afterwardsConstruction sections change. The imported structure stays editable without losing its reference to the model.
- For every process at onceDefects, photos, inspections and diary entries then all hang on the same structure.
What the model achieves during construction — and what it does not
The most common disappointment arises where something is expected from the model that it does not contain.
| Task | Model on its own | Model plus capture on site |
|---|---|---|
| *Structure and positioning* | Fully derivable from IFC | Unchanged, plus a link to the capture |
| *Checking the intended state* | Shows what is planned | Also shows what was actually built |
| *Construction progress* | Not included | Readable from the series of captures |
| *Defects and deadlines* | Not included | As a process on the building element, exchangeable via BCF |
| *As-built record after completion* | Design status, not the condition as built | The history, including building elements already closed up |
A model describes the intent. The construction phase needs evidence of the result on top of that.
Locating defects in the 3D model
When a defect is placed in the 3D viewer, the system stores the 3D coordinate and the camera position — the view can be restored exactly later on. In the model overview all defects appear as spheres, coloured by status. What a list records as "bathroom, right-hand wall" becomes a point that everyone involved finds in seconds.
- Screenshot as a recordThe model view is attached to the defect as an image — in addition to the photo of the building element, not instead of it.
- Status at a glanceDefects that are open, in progress or signed off are distinguishable by colour in the model.
- 2D remains just as validNot every project has a model. Positioning on the floor plan achieves the same thing in two dimensions.
IFC and BCF — the way back into design
For anything from the site to reach the design team, vendor-neutral formats are needed. IFC carries the model itself and suits central storage; BCF carries the issues that go with it — defect, viewpoint, comment, responsibility — without sending the model along. It is exactly this separation that makes collaboration between site management and the design office workable.
In practice that means: site management sends neither a model file nor a PDF list, but a BCF file that opens in the design tool.
Where BIM fails on site
A model nobody maintains
A design status from eight months ago misleads — worse than no model at all.
The wrong level of detail
A model that contains every screw cannot be used on a tablet.
Office only
Whatever does not run on mobile and offline never gets opened on site.
Without actual data
An intended state without an actual state produces no comparison, only an assumption.
An island solution
A viewer with no connection to the defect process creates duplicate work.
Better
Structure from IFC, processes on the building element, exchange via BCF, actual condition from the site walk.
From research: robots and models
Open Experience has worked for years on the interface between the BIM model and the reality of the building site — including in publicly funded research projects. The MAROON project (started 1 October 2018, funded by the German Federal Ministry of Education and Research under its "KMU-innovativ: Produktionsforschung" programme) developed a mobile assistance robot system for the tiling trade: Open Experience was responsible for the interface to BIM — tile positions and laying patterns were extracted from the model, and the tiles actually laid were written back from the robot control system. The satellite project BIM-4-CARE within the SmartLivingNext initiative (started 7 February 2024, together with Darmstadt University of Applied Sciences) is about feeding practical experience from nursing care into building design; there, a digital building twin is created from 360° captures.
Frequently asked questions
Do I need BIM in order to document digitally?
No. Floor plans are enough for positioning and structure. A model makes the allocation more precise and saves time when setting a project up — it is an advantage, not a prerequisite.
What is the difference between IFC and BCF?
IFC carries the model, BCF the issues that go with it: viewpoint, comment, status and responsibility. BCF files are small and can be exchanged between different tools.
What level of detail should the model have for the construction phase?
Enough for building elements to be identified unambiguously — and no more. For locating defects, the level of the space-forming elements and the building services is usually sufficient.
Does the 3D viewer work without an internet connection?
Capture on site works offline and synchronises later. For large models the tablet in the office is still the more comfortable environment.
Is the model updated by the data from the site?
Not automatically. What is written back are issues and their status, via BCF; a geometric as-built model does not come out of that — measurement or scanning is the route for that.
Is BIM worthwhile during construction on small projects?
If a model exists anyway: almost always, if only for the project structure. Having a model produced specifically for the construction phase rarely pays off.
Sources and legal basis
The legal statements in this article are based on the primary sources listed below. The article is not a substitute for legal advice in an individual case.
From the model to the site — and back.
45 minutes with your IFC file: import the project structure, locate a defect in the model, export BCF.