A section drawing is a drawing representing a building or building element as if cut through at a particular plane, so that its internal layout, heights and connections become visible. Sections, together with plans and elevations, form the basic drawings of any construction project.
What a section shows
A good section drawing communicates at least:
- Storey heights — clear height between floor and ceiling
- Build-up of floors and roof — structure, insulation, finish
- Structural elements — beams, columns, foundations
- Connections — windows, eaves, expansion joints
- Levels — relative to datum (zero)
- Slopes — falls of roofs and gutters
Types of section
In construction drawings several types are distinguished:
Longitudinal section
A cut along the long axis of the building, often through the main axis or central corridor.
Cross section
A cut along the short axis, usually placed where as many different rooms as possible are crossed.
Detail section
A partial section at a larger scale (1:5, 1:10) showing a specific connection such as an eaves or window detail.
Principle section
A schematic section that makes the structural concept clear, without full detailing.
Applications
Section drawings are used by everyone on a project:
- Architect — for design and communication with the client
- Structural engineer — for working out calculations
- Contractor — to understand how to build the work
- Building authority — for permits and approvals
- Services engineers — for routing pipes, ducts and heating
Points to consider when drawing
- Section line on plan — clearly indicate where the cut is made
- View direction — arrows show which way you are looking
- Scale — usually 1:50 for overall sections, 1:20 or 1:10 for details
- Connections — all floor, roof and façade junctions fully detailed
Related terms
- Plan
- Elevation
- Working drawing
- Detail
- Structure
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