The wall between inside and outside: a concept

The French architect Henri Ciriani used to tell the parable of Michelangelo’s square (an imaginary square that he might draw to start off a design). It stated that when Michelangelo drew a square, all sorts of decisions and conditions were already known and decided. michelangeloplan1aThat is, as soon as you know the length of one side of the square, you knew how high you could go because you know what it was being made of – stone or marble, for example. It also suggested mass, the amount of light that came in, how open or closed it was, and so on. This was given by the limitations and knowledge of available building materials and construction technologies. When Mies van der Rohe drew a square, nothing was decided. That is, with modern building technologies the height, density, character, transparency, etc., are all up in the air. Mies-50-01For Mies, even the fact that he might place steel columns at the corners meant very little. The proposed space could still be very high, or low, very open, or closed, massive or light. In this sense, for Ciriani, modern architecture requires that you decide everything, or put another way, that you determining everything. Pre-modern space was of considerably different character than modern space. The expectations of exterior space (generally public) where well-known as were those of interior space. I would add that Michelangelo’s square determines its walls or piers which in turn determine the relationship between interior and exterior – and it did this with a single gesture. The material was often the same on each side. Modern space is less clear about inside and outside. Picture here any canonical modernist project breaking the box with flowing exterior and interior space together here (Wright, Schindler, Rietveld, Mies). The modernist wall then had to qualify an increasingly uncertain and abstract exterior while qualifying an increasingly polyvalent and abstract interior. I have it from a good source that Herzog and de Meuron choose to privilege the inside or the outside. For example, when they want an exquisite flat and abstract exterior surface this means the details on the interior are often horrid (and vice versa). David Adjaye supposedly demands that both interior and exterior work equally well. This makes things much harder for the designers, detailers, builders and clients. It is not a question of a right or wrong approach; this is simply to say that there is a choice, and if there is a choice there is an issue, there must be something at stake.

It then occurs to me that Louis Kahn understood this problem and came up with an interesting solution. Knowing the differing demands of the inside versus the outside and the difficulty of reconciling these Kahn decided to make the wall spatial. More precisely he doubled most dividing surfaces (as did Michelangelo). salk_sectionFloor and ceiling become two planes rather than one. Exterior walls are doubled – one responds to the exterior, the other to the interior. It’s there in the Adler house, the Esherick house, the Bryn Mawr dormitories, Unitarian Church, Hurva Synagogue, Yale Art Gallery (in section), Salk Institute (see above image), Exeter Library, Kimball Museum (you’ll have to use you imagination with this one), Richards Medical Laboratories, and many of his unrealised projects. By the time he gets to Dacca he’s transformed this idea into something of great complexity – somehow entire buildings are treated as thicknesses. kahn daccaIn one swift move (but remember this took him years to develop), Kahn engages with the problem of modern space, the interior/exterior conflict, and with the multitude of choices brought on by modern technologies. That is, the technology of the outer skin does not have to impinge on the resolution of the inner skin. No compromise is necessary. This is, again, in no way meant to say that Kahn’s solution is best – Adjaye and H&M have taken different positions on this. What all of them recognise is a conceptual understanding of the problem of reconciling inside and outside space. This idea was speculative until I thought of Kahn. The clarity and rigor with which he articulates this notion of the wall and pier turned the hunch into a concept.

Michelangelo had it easy.

Centred, Peripheral and Dispersed Plan Types

Modernist discourse on space often proposes an opposition between spatial organisations that emphasise the centre versus those that emphasise the periphery. Classically planned buildings nearly always put the emphasis on the geometrical centre of the plan (see 1 square, 4 square, 9 square). Modern architects, in their attempt to link interior and exterior space, put the emphasis on peripheral spaces often eliminating a central space altogether. Since the middle of the last century another plan type, dispersed, did away with emphasis on either centre or periphery. This plan type reinforced the idea of networks, nets or labyrinths rather than fixed geometrical figures. For a time these inflections reflected cultural and social belief systems of their time.

Today we can plan as we like; there is no longer a dominant or shared ‘universal’ spatial order.  If anything, our pluralist contemporary values suggest that we must employ a variety of approaches rather than enforce any single one. In addition, we no longer see centralised plans and its implied hierarchy as inherently bad. It therefore becomes more important to understand the effects and implications of centralised, peripheral or dispersed organisations. For example, we should not see these as just geometrical ‘games’ but as different types of spatial intentions. Although modernist plans often avoided centralised spaces they often reinforced a non-geometrical centre or focus. In the work of Frank Lloyd Wright this was often the hearth; for Le Corbusier it was the double height space, designed as the social heart of a project but located peripherally. Read this was we can see that modernist plans had their own hierarchy even while displacing the symbolic centralised space of classical planning. Dispersed plans might be said to privilege movement rather than any particular space or object.

Although we are now free to use any plan type without the restrictions of a single cultural reading or technological constraint, locality and specificity of place can generate a meaningful choice of plan type. In addition, the plan type is no longer an automatic choice (based on the architect’s rigid belief system) but often evolved through a process of design investigations. Nevertheless, you are likely to eventually arrive at one of these plan types. The question to ask is whether the design intention is utilising the right tool (plan type) to be effective and communicable.

Source: Le Corbusier

Villa Rotunda, c.1580, Andrea Palladio. This is a classic nine-square plan following the geometrical schema quite closely. There are subtle adjustments worth noting: the circular central space emphasizing its importance; a non-symmetrical north-south versus east-west layout; achievement of four different scales in room sizes.

Villa Rotunda, c.1580, Andrea Palladio. Typical centralised and hierarchical plan

Frank Lloyd Wright, Martin House, 1906

Frank Lloyd Wright, Martin House, 1906. Peripheral plan with hearth at centre.

Le Corbusier, Maison Citrohan, 1919.

Le Corbusier, Maison Citrohan, 1919. Non-centralised plan with double height social space (at bottom).

Aldo van Eyck, Orphanage, 1962.

Aldo van Eyck, Orphanage, 1962. Example of dispersed or network plan with an emphasis on movement circuit.

Sanaa, Moriyama House, 2005.

Sanaa, Moriyama House, 2005. A contemporary dispersed plan. Note that this plan avoids reinforcing a centre, periphery or a movement system. In this case it is being used to neutralised as many aspects of space as possible.

Skin versus Wall

The vertical surface enclosing your project can be understood as either a membrane – a think veil separating inside and outside – or as a wall – a solid which requires mediation through windows, gaps or openings. The skin or membrane is generally a surface whose primary determinant is the exterior image. That is, it is a skin which wraps the building and whose articulation – joints, ribs, and pattern – is generally graphic in quality rather than directly determined by the interior.

The wall, by contrast, is articulated as a more solid and thicker surface that tends to act more as a mediator despite the fact that they are generally more opaque than skins (which tend to be transparent or translucent). Because the wall establishes an unambiguous limit (visual and physical) there is generally a tendency to be more considered about how connections are made between the interior and exterior. That is, windows are generally set with a greater concern for specific and framed views. Balconies or other punctures act specifically to join inside and outside. As such, although one may see less of the interior through a walled project than as with a skinned one, the relationship between inside and outside can be said to be more precise.

Paradoxically it can be suggested that skins, though often (but not always) permeable tend to draw attention to the surface as an object – a plane – and hence create a stronger barrier to interior/exterior relationships. Walls, through the more carefully and selective connections can act more as a connective surface linking inside and outside in a constructive manner.

Herzog & de Meuron’s Library for the Eberswalde Technical School. Skin. Note the graphical quality of the membrane.


Neutelings & Riedijk’s Veenman Printer building in Ede, Netherlands. Skin.

Neutelings & Riedijk, Apartment Building, Prinsenhoek. Wall. This project uses three different wall and opening articulations in the base, body and attic of the project to create different identities for each part.


MVRDV, Double House, Utrecht, Netherlands. Wall. This project might be seen to be ambigous, as technically the wall is a skin on a frame. However, the specifically created openings tend to render the solid surfaces as solids, and hence wall-like. The main distinction is in the opposition of open and closed surfaces as opposed to the continuous surface treatement of a skin or membrane.

Free Plan, Open Plan, Raumplan

In everyday usage ‘free plan’ and ‘open plan’ are often used interchangeably. They are, however, very distinct. A free plan comes into play when the role of structure is separated from that of enclosure of spaces. Generally, it arises through the use of columns that allow the partitioning of space to follow a logic other than that of the structural grid. In the best demonstrations of free plan (see Le Corbusier) the columns play a spatial as well as structural role, defining sub-zones, passage zones, or used sculpturally to create a greater sense of depth in space. An open span is a plan which is left largely unplanned, as in typical office towers or single space homes. In the first (free plan) there are always rooms, even if they are not entirely closed off, while in the second (open plan) there is only the perimeter.

A raumplan is a planning method based on discreet rooms and a dynamic section. This method places great emphasis on the scale of individual rooms and often requires steps into each room or cluster of rooms. The method largely belongs to the architect Adolf Loos and requires a high level of structural awareness and ability to model spaces.

Source: Le Corbusier & Adolf Loos. See Raumplan versus Plan Libre by Max Risselada.

Opacity, Transparency & Translucency

These are basic qualities of surface. Considering these early on can help you avoid treating spaces as defined only by walls. Opaque surfaces separately two sides completely and fully. The result is physical and visual separation. Transparent surfaces allow full visual connection while creating physical separation. Translucent surfaces create partial visual separation with either full or partial physical separation. A frosted or sand-blasted glass wall allows light and some visual clues to communicate while preventing physical connection.  A mesh or other type of screen allows slightly more visual information while allow facilitating sound and air movement.

Relationships between two spaces can be made complex when you begin to combine these three qualities in a single space or single surface.

Windows: Light, View, & Air

Windows are too often treated as nothing more than rectangular openings in walls. The window establishes a relationship between inside and outside for a variety of reasons. Windows may be used for light, views or ventilation – and they may developed to deal with these aspects individually or in combination. The size and form of a window also frames the relationship between in inhabitant and the exterior. A small opening may be used to frame a specific view; a horizontal window may relate to the horizon; a vertical one may allow the entire body to feel connected to the exterior. Some windows may be used for nothing but light, placed above eye level.

The placement of the window within the thickness of the wall also has consequences. Windows flush with the surface of the exterior tend to flatten the exterior wall possibly making the wall feel like a membrane. A window set towards the inside of the thickness of the wall helps the mass of the wall to be sensed and hence gives the wall a greater sense of weight. The placement within the wall also has particular effects on the interior.

Conceptually windows can be treated as: punctures in walls, preserving the integrity of the wall surface; cracks or gaps that interrupt wall surfaces; horizontal strips that sever the verticality of wall surfaces; etc.


See Constructing Architecture, Materials Processes Structures, ed. Andrea Deplazes, Birkhauser. There is a section on ‘Opening’ (p.200) which includes a discussion of the debate between Le Corbusier and August Perret on the horizontal versus vertical window, plus an outline of window types based on their formal properties (opening as a hole, opening as a horizontal strip, opening as joint, opening as a transparent wall).

Zones Instead of Walls

Imagine the boundary between inside and outside or between one room and another to be a zone rather than a wall. This will alleviate a number of problems and open up design possibilities. The zone can be articulated as a double wall, thick wall, inhabited wall or thick threshold. This thickness can be used to house storage spaces, mechanical systems, or be inhabited with window seats, built in furniture or other amenities. In some cases you may even be able to house circulation within the zone. This thickness can also be used to allow for differing sizes among adjacent rooms while avoiding an irregular overall building outline. That is, you can allow for differently sized rooms while keeping to geometrical alignments that can help maintain the clarity of your scheme – a series of rooms as a bar or a cluster or spaces reading as single larger figure. The zone gives you breathing room to negotiate internal needs with external clarity. Working only with walls (and particularly with walls of a single thickness) will create problems when you get into larger scale resolution of your design.

In practice you will find that thicknesses are required for many practical reasons – mechanical systems, plumbing, structure, wiring, and so on. It’s a good habit to develop early on.

Student Plan 1: This is a typical early plan made to test layout, scale, use and organisation. The spaces are concieved as independent cells defined by walls that have no identity other than doubled lines separating spaces from each other.

Student Plan 2: This is a series of plans testing layout, use and organisation. Again the spaces are defined by walls which are seen only as boundary defining elements. This results in an overly simplified wall/space opposition that lacks ambiguity, thresholds, in-between spaces or spaces with multiple characteristics.

Esherick House, Louis Kahn: This plan demonstrates the use of zones rather than walls to help organise and bring clarity to the plan layout. Note the exterior walls top and bottom which are treated as thick boundaries with niches on the interior side. The two living spaces are separated by a thick threshold comprising the stair and inset entry vestibules. During the design process it is likely that these zones were adjusted to resolve the interior spatial dimensions against the desire to produce a clear rectangular external volume.

Bryn Mawr Dormitories, Louis Kahn: This composite plan shows three different levels of the dormitory complex. Each level demonstrates different uses of the ‘wall as zone’ or ‘thick wall’. The band of bedrooms, in themselves, can be seen as a thick inhabited wall zone. Note that Kahn’s spaces are rarely defined by 4 straight walls, but are nearly always articulated to create thresholds or occupiable spaces.


Spence R. Kass ‘The Voluminous Wall‘ describes how the walls of St. Peters in Rome is really a thick space that is sometime occupied or used to modulate light. The article focuses on this one project but makes links to Louis Kahn and Alvar Aalto.

Related Post: Six Conditions of a Cube