One of the first questions we get is a very natural one:
“We already have the building’s drawings. Is there any point in scanning it?”
Sometimes, no.
If the drawings are recent, have been checked on site and the project does not need high accuracy on the existing condition, they may be enough.
The problem arises when nobody knows exactly how much of the drawing still matches today’s building.
A building does not necessarily stay identical to the documentation it started with.
Partitions appear. Openings are blocked or moved. Floors are raised. Ceilings are lowered. Small extensions. Local interventions. Some are documented. Others are not.
At that point, the question is no longer whether drawings exist.
The question is how much you can trust them.
Are the existing drawings wrong?
Not necessarily. It would be simplistic to assume that every old drawing should be thrown away. Some documentation is very good. It can be enough for preliminary studies, administrative checks or concept discussions.
But a drawing represents the building at a particular moment. If the current project involves work on the existing building, small differences can start to matter.
A wall a few centimetres out may be irrelevant at concept stage. In a construction detail, it can become awkward. A façade slightly off-axis can go unnoticed in a general plan. It becomes important when you start coordinating openings, joinery, structure and finishes.
That is why existing documentation should not be viewed with suspicion. It should be checked against the purpose of the project.
A real case: Casa Albă Băneasa
An interwar villa. Drawings existed. The building also had interventions made over time, without a permit and without appearing in any documentation.
For regularisation and restoration, the question was not whether the drawings were good. It was what in today’s building did not appear in them.
The scan gave the real geometry of the whole building, including the undocumented interventions. The old drawings remained useful for understanding what was designed. The difference between the two became the subject of the project.
Project details: Casa Albă Băneasa.
When are the drawings you already have enough?
For some projects, scanning does not add enough value to justify the cost.
A simple apartment. Regular geometry. No structural work. No complex façades. No BIM requirement. No complicated coordination with visible services or existing elements.
Here a well-made conventional survey can be perfectly reasonable. The same applies when the documentation is recent and comes from a survey you trust. Not every building needs a point cloud and a three-dimensional model.
The decision should be tied to risk. If an error of a few centimetres changes nothing important in the project, it may not be worth paying for more detailed documentation. If the same centimetres can affect façades, structure, fitted furniture, services, joinery or quantities, the situation changes.
What 3D scanning checks that drawings don’t always show
First, the relationship between elements. Not just the length of a wall. But its position relative to the other walls. To the columns. To the openings. To the floor slab. To the level above.
Then come the things a real building does without asking the drawing’s permission.
Walls are not always perfectly parallel. Openings are not always centred. Floor slabs can have level differences. Façades can deviate.
Older buildings are even less willing to respect the elegant geometry software prefers.
That does not mean the model should be “straightened”. If the purpose is design on an existing building, the real geometry is the useful information.
Why small differences matter in a large project
Because they add up.
A medical clinic in Bucharest. A 30 cm deviation that appeared in no documentation. The medical furniture was custom-made, already in the design. The scan caught the difference before the order. The amount avoided: about 30,000 EUR.
Nothing dramatic on its own. A wall, a few centimetres. Except that, in that spot, the centimetres had a price.
For a developer, this is the key point. Scanning is not valuable because it produces a spectacular point cloud on screen. It is valuable if it reduces the number of unknowns that design pushes further down to construction.
Elias Hospital: checking without stopping activity
At Elias Hospital, the existing drawings could not be checked with a tape measure among patients. The building was scanned in operation, without interrupting medical activity, and the resulting BIM model became the base for designing the extension.
The existing drawings remained useful. They explain the history of the documentation and provide information that geometric measurement cannot deduce on its own. The scan added verification of the visible situation on site. The two sources do not exclude each other. They complement each other.
The same principle applies to a house, a hotel or an office building. Only the level of complexity differs.
Does scanning replace the old drawings?
Not always. It is more accurate to say it checks and complements them.
Existing drawings can contain information about the structure, earlier phases, uses or elements that are no longer visible. Scanning documents what can be observed and measured at the time of the survey. It does not see through walls. If a service is hidden in masonry or in a floor slab, it stays hidden.
For design, the combination of existing documentation and the measured situation can be the most valuable.
Is scanning worth it for a house, or only for large buildings?
Size is not the main criterion. Complexity matters more.
A 400 m² house with many levels, a complicated roof, a basement, irregular façades and successive interventions may need more careful documentation than a hall of several thousand square metres with simple geometry.
For an ordinary house, scanning on site takes at most one day. The important part comes after: registering the data, checking, modelling and extracting the required documentation.
When is it worth scanning even if you have the drawings?
It is worth considering scanning when:
- the project involves significant work on the existing building;
- the building has irregular geometry or many levels;
- the drawings come from different sources and do not overlap well;
- changes were made after they were drawn;
- you need precisely coordinated elevations and sections;
- the project will continue in a BIM workflow;
- an error discovered late would cost significantly more than checking at the start.
It is not a universal rule. It is a project decision.
What to ask before ordering a 3D scan
Do not compare quotes only on floor area and price. Ask what you will actually be able to do with the information you receive.
For an architect, what matters is whether the geometry is accurate enough for design and in which format it will reach the office. For a developer, the question is whether the documentation reduces later checks and uncertainty in the budget.
One more thing matters: the level of modelling. A simplified model and a model carefully built on the existing geometry can start from the same scan data, but they do not involve the same amount of work. That is why two quotes for the same floor area can be very different.
Frequently asked questions
If I have cadastral plans, do I still need a scan?
It depends on the project. Cadastral plans may be enough for some administrative purposes, but they are not always the right base for detailed design or BIM modelling.
Can scanning confirm whether walls are structural?
Not on its own. Scanning shows the visible geometry. Identifying the structural role must be done by the competent specialist, also using other information about the building.
Can old drawings be compared with the current situation?
Yes. That comparison is exactly what is useful when changes are suspected or when the documentation comes from several periods.
How long does scanning a house take?
On site, at most one day for an ordinary house. Final delivery includes processing and, if requested, modelling or drawing — the timeframe depends on the deliverables and complexity.
What to do next
If you already have drawings of a building, the first step is neither to throw them away nor to order a scan automatically. Check what decision you need to make based on them and what it would cost you if the information is insufficient.
For price ranges and examples of situations where scanning makes sense, see how much a 3D scan costs.