Making ground

We are asked, fairly often, why a studio with good computers still begins every project with a soft pencil and a roll of thin paper. The honest answer is speed. A line on paper costs nothing, so you draw fifty of them, and the forty-nine wrong ones teach you what the right one has to do.

A sentence can leave things out. “The living room opens to the garden” sounds finished. Draw it and you have to decide how wide the opening is, what holds up the wall above it, where the step goes and which way the door swings. The drawing asks every question the sentence avoided.

The section comes first

Most people start with a plan, because a plan looks like a map and maps are familiar. We start with the section. It shows the things that make a room feel the way it does: how high the ceiling is, where the light enters, how the floor meets the ground outside.

On Pedreira Terraces the first drawing that survived was a section about the width of a hand. It showed one roof, one window and one person. Everything that came later was an argument with that sketch, and the building that stands in Braga is still recognisably it.

What a drawing has to carry

A working drawing is an instruction to someone you may never meet. It has to survive being photocopied, folded, rained on and read at arm's length on a scaffold. That is why the conventions matter:

• What is cut is drawn heavy; what is seen beyond is drawn light.
• Dimensions run in chains, so nobody has to add up on site.
• Every grid line has a name, and every sheet uses the same ones.
• Levels are given from one datum, written on the drawing.

None of this is nostalgia. The same plan lives in a model on a server, and the contractor builds from that. But the model is where a decision is recorded. The pencil drawing is where it gets made.

On site

The test of a drawing is whether the building can be read the same way. Stand in the finished room with the section in your hand and you should be able to find the line you drew.

When that works, nobody notices. They just say the room feels right. We take that as the drawing doing its job.