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Architectural sections and elevations are 2D representations of a building: sections show a vertical cut through the structure as a building section, including heights, assemblies and floors. Elevations show the visible sides of a building as an exterior view, or facade elevation. Ideally, both are based on current survey and model data.
Why are sections and elevations important?
- Reliable basis: Heights, layer assemblies, openings and details become clearly readable, reducing planning errors and change orders.
- Derivations and quantities: Consistent sections and elevations provide the basis for details, bills of quantities and facade developments.
- Interoperability: Clean drawings flow directly into CAD/BIM, tendering, approvals and documentation.
- Evidence and quality: Dimension chains, tolerances and references to standards support acceptance and eligibility for funding.
How sections and elevations are created in practice
- Data basis: Digital measurement, such as TLS, SLAM or photogrammetry, produces a point cloud or orthophotos. Alternatively, an existing building model can be used, for example from scan-to-BIM.
- Quality assurance: Registration, check points, documented tolerances in mm/cm and RMS error are recorded. The coordinate system and units, such as m/mm, are defined.
- Derivation:
- Section: A cutting plane is placed in the point cloud or model. Components are modeled, and elevation markers, layer assemblies, stairs, slabs and penetrations are added.
- Elevation: Generated from an orthographic projection or model. Openings, facade grids, materials and joint patterns are shown.
- Structure: Layers/styles, line weights, symbols, dimensions and legends are kept consistent. The scale is selected to match the level of detail.
- Delivery: DWG/DXF/PDF for 2D. For BIM, IFC is also provided for geometry and attributes, together with metadata on version, date and accuracy.
Types and use cases
- Building sections, including longitudinal and cross sections, as well as detail and construction sections.
- Exterior elevation for each side of the building according to orientation; facade development or orthographic projection for precise dimension chains.
- Approval, construction and revision drawings, including as-built plans.
Common errors and misunderstandings
- Old plans instead of as-built condition: Historical drawings are not evidence. Current measurement data should be used.
- Unclear units/references: Confusing m and mm or missing a zero point creates follow-on errors.
- Inconsistency between floor plan, section and elevation: Different layers, dimension chains or component statuses confuse trades.
- Only geometry, no information: Missing elevation markers, layers, materials and detail notes slow down construction.
- Missing QA: Without check points/RMS and a version log, traceability is reduced.
Sections and elevations vs. Orthographic projection
- Orthographic projection: Distortion-free representation of the facade from point clouds/photos, ideal for precise dimensioning and facade development.
- Elevation: Drafted representation with symbols, materials and legends according to planning standards.
- Best practice: Use the orthographic projection as the basis and derive standard-compliant elevations from it.
FAQ
How do I derive reliable sections or building sections from scans?
Reference the point cloud, for example E57/LAS/LAZ, define cutting planes and model the components. QA is carried out using check points/RMS and documented tolerances.
When should I use orthographic projections for elevations?
When high accuracy is required for facade dimension chains, opening schedules and developments. Orthographic projections provide a distortion-free basis.
Which formats should sections/elevations be delivered in?
DWG/DXF/PDF for 2D plans. For BIM, IFC should also be provided for geometry and attributes, always with metadata on version, units, coordinates and accuracy class.