The section as relato makes immediately visible what the plan obscures: whether a void in a building is a light well or an interior courtyard. The proportions — height relative to width and length — determine the spatial experience, the amount of daylight that reaches adjacent rooms, and whether the void is habitable outdoor space or purely a functional aperture. In residential design, the distinction carries significant consequences for how the house performs and what it costs to build.
The Proportional Threshold
The clearest way to define the distinction is through the section drawing. A light well and an interior courtyard are both vertical voids penetrating through the building mass. What differentiates them:
Light well:
- Width: typically 0.8-2 m
- Height-to-width ratio: often 3:1 or higher
- Function: delivers sky light and passive ventilation to interior rooms; not designed for entry or occupation
- Ground condition: paved or planted, with a drain — but no occupancy intended
Interior courtyard:
- Width: minimum 3 m, typically 4-8 m in residential work
- Height-to-width ratio: 1:1 to 2:1 for residential
- Function: outdoor living space — seating, planting, water elements; rooms open directly to it
- Ground condition: designed as an outdoor floor with furniture, landscape, and defined circulation
The section drawing to scale is the test. If the void looks like a shaft — narrow, tall, with a small patch of sky visible at the bottom — it is a light well. If it looks like a room without a roof, with walls and floor that invite occupation, it is a courtyard.
How Each One Delivers Daylight
The daylight factor — the ratio of interior illuminance to exterior illuminance — changes dramatically with the proportions of the void.
For a light well 1.5 m wide and 5 m deep:
- The adjacent room receives 0.5-1% daylight factor — adequate for a corridor or bathroom, insufficient for a living room or bedroom
- Direct sun enters the well for only a brief period each day (when the sun is directly above), if at all
For a courtyard 5 m wide and 4 m tall:
- Adjacent rooms receive 2-4% daylight factor — adequate for living, dining, and bedroom use
- Direct sun enters the courtyard for several hours each day, depending on orientation
- The sky visible from a seated position in the courtyard is generous
This difference in daylight quality is the primary reason to choose a wider courtyard over a deeper light well when the program and footprint allow. The section proportions set the light budget for every room that faces the void.
What a Light Well Can Solve
A light well is the right solution when:
- The building footprint is too small to accommodate a full courtyard
- The program only needs to illuminate a corridor, bathroom, or secondary room
- The architectural expression calls for a contained, dramatic vertical element rather than a generous outdoor space
- Budget is a constraint — a light well requires significantly less perimeter construction than a full courtyard
In a dense urban building with a 6 x 20 m lot, a full courtyard may not be feasible at the front or back. A 1.2 m light well at the center of the plan provides daylight to the kitchen and a secondary bathroom without requiring the lot area that a full courtyard would consume.
The Structural Implication in Section
Both light wells and courtyards interrupt the structural grid. In a reinforced concrete frame building, this means a void in the slab at every level. The void is surrounded by beams and columns. The section drawing shows where these structural elements land and whether they conflict with the program.
A narrow light well (1.5 m) can typically be accommodated within a standard structural bay without additional columns. A wide courtyard (5 m) requires columns at the four corners of the void — which appear as visual elements in the courtyard and should be designed accordingly.
Materialidad honesta: in MÉTODO, the structural columns around a courtyard are not clad or hidden. They are concrete, dimensioned to carry the actual load, and treated as the courtyard's vertical rhythm. The column is the finish.
Section-Driven Light Well Design
When a light well is the right solution, the section design must still be deliberate. Variables to resolve:
- Top opening: completely open to sky (maximum light, direct sun possible, requires drainage and bird protection); or covered with a diffusing element (glass, polycarbonate) that provides consistent north light without direct sun
- Reflectance: light-colored walls at the top of the well and dark or planted surfaces at the bottom maximize light distribution. A white-painted light well delivers three times the daylight of the same geometry with dark masonry walls.
- Water and drainage: the bottom of any light well must drain without any standing water risk. The detail at the base — drain, slope, junction with the wall waterproofing — must be resolved in the construction drawings.
- Planting: shade-tolerant plants (ferns, moss, small palms) at the base of a light well add life without requiring the sun hours unavailable in a narrow void
Próximos pasos
The decision between a light well and a full interior courtyard belongs in the first week of schematic design — not in the construction documents. Once the structural frame is set and the slab penetrations are fixed, the proportions are locked. The section drawing, produced early and at scale, is the tool that makes this decision visible and testable before it is irreversible.
Conoce el método de MÉTODO to understand how we use section drawings as primary design instruments from the start of every project.