Poche in architecture is the filled area of a plan or section where the cutting plane passes through solid material, usually walls, columns and floor slabs. Rendering that mass in black or a dense tone pushes it into the background, so the rooms left between it read instantly as usable space rather than as empty paper.
What Poche Means in a Plan Drawing
Every plan is a horizontal slice, normally taken about 1.2 metres above the floor. Whatever it passes through gets cut, and poche is the decision about how to render those cut faces so a reader can tell mass from space without a single label.
The effect is an inversion. Fill the walls and your eye stops seeing them as objects; they become the ground, and the rooms become figures sitting on it. That is the plan version of the solid and void reading architects use at every scale. Without it a plan is parallel lines the reader decodes one by one, which is why line weight in architectural drawing and poche are taught together.
The word is French, from pocher, to block in or sketch roughly, and it is often written with an accent as poché. It names a job rather than a style: separate what is cut from what is merely seen.
Where the Word Came From
Poche entered architectural vocabulary through the ateliers of the École des Beaux-Arts in nineteenth century Paris, where students inked the cut walls of their competition plans in black wash. In masonry construction the walls really were that thick, so the convention matched the building.
Those plans used wall mass for more than structure. A plan had to hold a strict axial parti on an awkward city site, and the leftover geometry got absorbed into the thickness: stairs, closets, light wells and odd triangular gaps disappeared into the poche so the main rooms stayed pure. Our guide to Beaux-Arts architecture covers the movement behind that logic.
📌 Did You Know?
Modernists spent decades dismissing Beaux-Arts drawing as academic decoration. The reversal came when the Museum of Modern Art gave the school a full exhibition, The Architecture of the École des Beaux-Arts, from 29 October 1975 to 4 January 1976 under Arthur Drexler.
Poche vs Hatch: What Each One Does
Students often use the two words as if they named one tool. Poche answers "is this cut?" while hatch answers "what is this made of?" A drawing can carry both, and at working drawing scale it usually has to.
Poche and Hatch Compared
| Aspect | Poche | Material Hatch |
|---|---|---|
| Question answered | Is this element cut? | Which material is this? |
| Typical fill | Solid black or dense grey tone | Coded pattern of lines or dots |
| Usual scale | 1:500 to 1:100, concept and presentation | 1:50 to 1:5, technical and detail sets |
| Governed by | Office or school graphic convention | Standards such as ISO 128-3:2022 |
Rules for representing cuts in technical documents sit in ISO 128-3:2022, Views, sections and cuts, which covers hatching of cut areas alongside section types. Presentation poche is looser, deliberately, because its job is communication rather than fabrication.
How Thickness and Tone Change the Reading
Poche is where a drawing declares whether the building is carved or assembled. A 400 mm stone wall filled solid black reads as mass with rooms hollowed out of it. A 90 mm stud partition drawn as two hairlines reads as a screen in open space. Same technique, opposite claim.
Scale sets the limit. A 300 mm wall measures 6 mm on a 1:50 sheet, 3 mm at 1:100 and only 1.5 mm at 1:200. Below roughly 1 mm a hatch collapses into grey mush, which is why small scale plans move to solid fill. Check the fill against the drawing's architectural drawing scale before you commit and you save a replot.
Tone is the second dial. Pure black gives the hardest figure ground separation and suits a single presentation plan, while a 60 to 70 percent grey keeps that reading and still leaves room for a darker line marking structure inside the wall.
Rooms That Live Inside the Wall
Thick poche is not dead material. The solid mass carried structure in masonry buildings and also held buffer zones, stairs and concealed servant corridors, a point argued in the 2023 MIT Department of Architecture thesis What's in a Poché? Once steel and concrete removed the need for depth, inhabited thickness became a choice.
Louis Kahn made that choice explicit by splitting a plan into served and servant spaces. Laboratories, reading rooms and galleries were served. Stairs, ducts, shafts and toilets were servant, and he gave them their own volumes instead of burying them in leftovers.
🎓 Expert Insight
"I conceived its design in recognition of the realizations that science laboratories are studios and that the air to breathe should be away from the air to throw away." Louis I. Kahn, on the Alfred Newton Richards Medical Research Building (1957 to 1965)
Kahn pulled the shafts out of the wall and stacked them into brick towers, so the servant zone older plans hid inside poche became the building's public face.
The studio lesson is practical. Before you fill a wall black, ask what is inside it, and if a 600 mm zone carries risers, a wardrobe and an acoustic gap, show that with a thin outline inside the fill.
Poche at City Scale: The Nolli Map
The same logic scales up. A figure ground plan treats built mass as poche and streets as void, which turns urban grain into something readable in a second. Giambattista Nolli pushed the idea further in his 1748 plan of Rome by leaving church interiors, courtyards and colonnades white wherever the public could walk in.
🏗️ Real-World Example
Nuova Pianta di Roma (Rome, 1748): Nolli hatched private building mass and drew accessible interiors as rooms continuous with the street. The interactive Nolli map from Stanford's Spatial History Project lets you switch layers such as buildings, fountains and the rioni on and off, then export a view for your own site analysis.
Borrowing the move is easy. Poche what the public cannot enter, leave white what it can, and the site plan starts arguing about access instead of listing footprints.
How to Draw Poche in CAD and BIM
In CAD, put the fill on its own layer and colour so you can swap solid for pattern without touching geometry. Solid fill is the safer default at 1:100 or smaller, and a pattern earns its place only when a reader can count the lines.
In Revit or ArchiCAD the cut pattern lives in the material or wall type rather than the view, so overriding it view by view is how a set drifts out of agreement. Set it once at material level and let every drawing inherit it.
💡 Pro Tip
Print a test A3 before committing a sheet to solid black. Toner and inkjet both spread, and a fill that looks crisp on screen can close the 1 mm gap between a wall and its column on paper. Many offices drop to about 80 percent black for large areas and keep pure black for the cut line at the wall face.
Two habits keep a set consistent. Draw the cut outline heavier than the fill edge so walls hold shape when reduced, and never let poche appear on anything the plane does not cut.
Poche in Competitions and Portfolios
Juries read plans at speed, often reduced on a screen, and black mass survives that compression while thin linework does not. The same holds for portfolio plan pages, where a reviewer may give a sheet ten seconds.
Use it as an editing tool: one tone for cut mass, a lighter tone for ground or context, white for the spaces you want noticed. Our guide to architecture competitions for students covers how boards are judged, and the drawings in 50 section drawings worth studying show how far the technique goes vertically. To start from prepared fills, our architecture graphics collection and pattern sets cover what most studio sheets need.
Common Poche Mistakes to Avoid
Too much black is the frequent one. When walls, context and shadow all go solid, the plan loses its figure ground reading, so keep filled mass as the minority of the sheet. Close behind is drawing walls at a thickness you never checked, since a line offset by an arbitrary amount produces a plan nobody can build.
The rest are consistency errors: fill that changes tone between floors, a hatch scale that shifts with the view scale, and fills applied to uncut elements. Each one tells a reader the drawings were assembled rather than designed as one set.
Putting It All Together
Poche outlived the masonry walls that produced it because it was never really about stone. It decides what a drawing treats as background and what it treats as subject, and that decision is architectural before it is graphic.
Frequently Asked Questions
What does poche mean in architecture?
Poche means the filled representation of anything the plan or section cut passes through, most often walls, columns and slabs, usually as solid black or a dark tone. Its purpose is to separate cut mass from visible surfaces so the plan reads as space rather than lines.
How is poche different from hatching?
Poche marks that an element is cut, while hatching says what it is made of. Poche is generally a solid or near solid tone used at presentation scales. Hatching is a coded pattern used in technical drawings where material identification matters, following conventions such as ISO 128-3:2022.
Should poche be pure black?
Not always. Pure black gives the strongest contrast and suits a single hero plan, but large solid areas can clog on paper and leave no room to show structure inside the wall. Many offices use 60 to 80 percent grey for the fill and keep pure black for the cut outline.
How thick should the poche wall be?
Draw the real thickness of the assembly rather than a fixed graphic offset. A typical interior stud partition sits near 100 mm, a masonry cavity wall near 300 mm, and a Beaux-Arts stone wall often passed 600 mm. Set the wall type first, then apply the fill.
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