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A planimetric survey captures the position, shape and dimensions of buildings or building components on a two-dimensional plane. For existing buildings, it is primarily used to document floor plan geometry, outlines and areas and to derive reliable 2D drawings for planning, refurbishment and area analysis.
Why is a planimetric survey important?
- Capture floor plans reliably: Walls, openings and room outlines are documented with accurate dimensions.
- Determine areas reliably: The captured geometry provides the basis for area calculations and room books.
- Update as-built drawings: Actual building geometry can be compared with existing plans and corrected where necessary.
- Simplify planning: Up-to-date 2D data provides a reliable basis for alterations, refurbishment and tendering.
- Enable digital processing: Results can be transferred directly into CAD, BIM or CAFM workflows.
How does a planimetric survey work?
1. Define the reference plane
The first step is to define the plane to be surveyed. In a building, this is typically the horizontal floor plan plane of a storey.
2. Capture the relevant geometry
The survey may include:
- Wall layouts
- Internal and external corners
- Doors and windows
- Columns
- Stairs
- Room boundaries
- Building and façade outlines
Depending on the project, the geometry can be captured using distance meters, total stations, laser scanners or other digital surveying methods.
3. Transfer the geometry to the plane
The measurement data is combined into a two-dimensional representation. This can be used to create room outlines or building floor plans, for example.
4. Derive areas and dimensions
Lengths, perimeters and areas can be calculated from the closed geometry and assigned to the relevant rooms or usage areas.
5. Process the results
The data can be provided as a floor plan, as-built drawing or CAD file and used for area surveys, planning, refurbishment or building operations.
Typical applications
- As-built floor plans: Planimetric surveys provide up-to-date room and building geometry when existing plans are unavailable or no longer reflect the actual condition.
- Area calculations: Closed room and building geometries provide the basis for calculating floor areas and usable areas in accordance with the relevant standard.
- Alterations and refurbishment: Current wall layouts, openings and room dimensions reduce uncertainty when planning work in existing buildings.
- Room books and facility management: Planimetric geometry can be linked to room numbers, uses and other property data and then used in CAFM systems.
Quality criteria
- Clearly defined reference plane and measurement specifications
- Complete capture of all relevant room and building boundaries
- Closed and geometrically consistent outlines
- Documented measurement accuracy
- Consistent units and references
- Traceable allocation of rooms and areas
For existing buildings, it is particularly important not to automatically idealise actual deviations. Walls that are not perpendicular or irregular room outlines may be relevant to planning and area calculations.
Common errors and misconceptions
- Planimetric does not automatically mean “manual”: Data obtained through laser scanning or other digital methods can also be evaluated planimetrically.
- Capturing dimensions instead of geometry: Individual lengths are often insufficient for complex room shapes.
- Assuming perpendicular walls: Existing buildings frequently deviate from idealised floor plans.
- Unclear area calculation rules: Capturing geometry and calculating areas are two separate steps. The applicable standard must be defined separately.
- Using old plans without verification: Existing drawings should be checked against current measurement data.
Planimetric survey vs. tachymetric survey
The terms describe different aspects of a survey.
Planimetric survey
- Focuses on two-dimensional position and geometry
- Typically produces a floor plan, outline or area geometry
- Can be created using different surveying methods
- Describes a specific surveying method using a total station
- Captures angles and distances
- Provides spatial point coordinates in 2D or 3D
A tachymetric survey can therefore provide data for a planimetric representation. The terms are not direct opposites: “planimetric” primarily describes the geometric plane under consideration, while “tachymetric” describes the measurement method.
Planimetric survey vs. area survey
A planimetric survey captures the two-dimensional geometry and position of areas and outlines.
An area survey focuses more closely on the resulting area values and their calculation in accordance with a defined standard.
In practice, a planimetric survey frequently provides the geometric basis for an area survey.
FAQ
What data does a planimetric survey produce?
Typical results include wall and room outlines, building footprints, dimensions, area geometry and the resulting 2D floor plans or as-built drawings.
Is a planimetric survey always two-dimensional?
Yes. Planimetry fundamentally refers to geometry on a plane. However, the underlying measurement data may have been captured using three-dimensional methods such as laser scanning or tachymetric surveying.
When is a planimetric survey suitable?
It is particularly suitable for producing as-built floor plans, calculating areas, planning alterations and refurbishment, and creating or updating room books and as-built drawings.