Spatial experience is fundamental to architecture, and that experience is dominated by the vertical rather than the horizontal: the shape and height of ceilings, the definition of space by walls and planes, the light through doors and windows. 

We are far more cognisant of height than area, from a Petit and Sevitt Split Level J, to the sloping roof in Ken Woolley’s Mosman house, to the woven beams in the dome of the Griffins’ Newman College, to the drama of the three big galleries of Col Madigan’s Australian National Gallery (NGA).  We are creatures of the vertical.

Verticality and space are best shown in the drawing of a section, yet the plan is the common drawing in architecture, the horizontal. Both plan and the section have the same basis: a cut made through the building at a chosen point to illustrate organisation.  The convention is that a plan is a cut at eye level so you can see spatial arrangements, furniture layouts and it picks up the position of windows and doors. A section is a vertical cut chosen to illustrate the volume of space, doors, windows and wall finishes.

The default to plan over section is somehow ingrained. Most clients bring a sketched plan as part of their brief, not just for houses but for all nature of buildings. It is a way of understanding what they are asking for: allocating spaces and names in order to understand the relationship of its parts.  In 40 years of studio practice, I have received many of these amateur plans, but never a section.

The section is the domain of the professionally-trained as it examines the more difficult concepts of a building – the shape of space, the width to height ratio, the manner of light and air, the structure for holding it up, and so on.  It is the hallmark of professional training, often seen in the difficulty of getting students in the early years at architecture school to draw a section with every plan.

Moreover, the section is the basis of sustainable thinking.  Everything about passive and active building design - thermal comfort, sun and light, shade, fresh air and ventilation, services delivery - is far more redolent in section than in plan. 

What is the angle of the sun entering the building; how far into the building; what thermal mass does it land on; what material does it strike; what is the overhang or shading – pergola, eave, roof structure?  What natural light comes in; where are the windows, skylights or fanlights; what is the throw of light; the dark and light spaces?

What are the possibilities for cross or stack ventilation; for night flushing or diurnal cooling with air running across high thermal mass ceilings? How will that air come in or be exhausted, naturally or mechanically, through vent shafts (or a Malqaf)? What materials enclose the spaces, what structure, what spans? What is the haptic sense of the surfaces; of floors, walls and ceilings? 

The answer to these, and more, is only found in the section.

Many council approvals now require answers to the questions of sustainability to be shown in a diagram filled with arrows and notes, even though the sun and wind don’t always come from the ‘right’ directions, or follow the convoluted paths, on an architect’s drawing. Indeed, some diagrams are hilariously silly. Nevertheless, the three essentials of architectural science: heat, light and sound, are always best explored and demonstrated in a section.

An architect’s plan may resemble the client’s, may even follow it literally, but that doesn’t make a building. It is the development of that plan into a section - the varying heights, materials, qualities of light into a variety of rooms and spaces - that ultimately creates the architectural experience that the client has commissioned.  Amateurs may draw plans, but it is for professionals to uphold and explain the qualities of their architecture through the section.

It is for all those reasons – space, sense and sustainability – that the section is the key drawing in a presentation or competition. From an open house to the Opera House and everything in between.

Architecture is designed space. And that space is designed in section.

Tone Wheeler is principal architect at Environa Studio, Adjunct Professor at UNSW and is President of the Australian Architecture Association. The views expressed here are solely those of the author and are not held or endorsed by A+D, the AAA or UNSW. Comments can be posted here or addressed to [email protected]