How to Read an Architectural Drawing: Plan, Section and Elevation

An architectural drawing shows a building in plan, section and elevation, at a set scale and with standardised symbols. The plan is a horizontal cut seen from above, the section a vertical cut and the elevation a view from outside. Together they give a complete picture of the building’s rooms, heights and appearance.

Facts

Three basic views

Architects describe a building with three kinds of drawing. The plan shows how the rooms lie in relation to each other; imagine sawing the house off a little above the floor and looking down. The section shows a vertical cut, for example through the nave of a church, and reveals heights, vaults and load-bearing parts. The elevation is a view from outside without perspective, showing windows, doors and roof shape.

The drawings belong together. One reads the plan first to understand the rooms, then the section to understand the heights and finally the elevation. Read more about the parts of a building under the façade and roofs, and about how to look at buildings in the section on seeing architecture.

Scale, lines and symbols

The scale tells how much the drawing is reduced. 1:100 means that one centimetre on the paper is one metre in reality, and 1:50 gives more detail. Site plans are often drawn at 1:500 or 1:1000. Dimensioning with figures and dimension lines gives exact measurements. Always check the scale bar if the drawing has one.

The lines have different meanings. Thick lines show cut walls, thin lines are what is seen beyond the cut and dashed lines show hidden parts or what lies above. Doors are drawn with a quarter circle showing which way they swing, windows as thin double lines in the wall. Stairs have an arrow pointing up, and a north arrow gives the compass points. The rooms have names or numbers, and heights are given in metres above a zero level, for example +0.00.

Reading some famous plans

The Pantheon in Rome has a simple plan: a round hall with a rectangular porch with columns. The section shows that the height of the hall equals its width, so that a sphere would fit inside; the dome is a hemisphere. The Parthenon is a rectangle with columns around a cella; read about the columns in the guide to the classical orders and about the temple.

Villa Rotonda by Palladio is square with four identical porches and a round hall in the middle. The plan shows the symmetry that is otherwise hard to grasp; see the guide to Palladio. Chartres Cathedral has a cross-shaped plan with nave, transept and choir, described in the guide to the parts of a church and under the church.

Baroque and modern plans

In the Baroque the plan becomes a composition of curves. San Carlo alle Quattro Fontane by Borromini has an undulating plan in which the walls swing in and out, and the section shows an oval dome covered with geometric coffers. The interplay between plan and section becomes especially important when the vaults are complex; read about the technique in the guide to vaults and arches.

Villa Savoye by Le Corbusier shows modernism’s free plan. The plan is an almost square box with columns in a regular grid, and the walls can be drawn freely. A ramp in the middle leads upwards through the house, which is best seen in the section. Read more in the guide to functionalism. Remember that perspective drawings and axonometrics are illustrations, whereas plans are exact; compare linear perspective and composition.

How to recognise it

Exercise

What does a section drawing show?