Problem
We have established in Thick Walls (197), how important it is for the walls of a building to have “depth” and “volume”, so that character accumulates in them, with time. But when it comes to laying out a building and constructing it, this turns out to be quite hard to do.
Solution
Mark all those places in the plan where seats and closets are to be. These places are given individually by Alcoves (179), Window Place (180), Thick Walls (197), Sunny Counter (199), Waist-High Shelf (201), Built-in Seats (202), and so on. Lay out a wide swath on the plan to correspond to these positions. Make it two or three feet deep; recognize that it will be outside the main space of the room; your seats, niches, shelves, will feel attached to the main space of rooms but not inside them. Then, when you lay out columns and minor columns, place the columns in such a way that they surround and define these thick volumes of wall, as if they were rooms or alcoves. For shelves and counters less than 2 feet deep, there is no need to go to these lengths. The thickening can be built simply by deepening columns and place shelves between them.
Related Patterns
… the arrangement of roof and floor vaults will generate horizontal outward thrust, which needs to be buttressed - Cascade of Roofs (116). It also happens, that in a sensibly made building every floor is surrounded, at various places, by small alcoves, window seats, niches, and counters which form “thick walls” around the outside edge of rooms - Window Place (180), Thick Walls (197), Sunny Counter (199), Built-in Seats (202), Child Caves (203), Secret Place (204). The beauty of a natural building is that these thick walls - since they need lower ceilings, always, than the rooms they come from - can work as buttresses.
Once the Roof Layout (209), and the Floor and Ceiling Layout (210) are clear these thick walls can be laid out in such a way as to form the most effective buttresses, against the horizontal thrust developed by the vaults.
In order to make an alcove or thick wall work as a buttress, build its roof as near as possible to a continuation of the curve of the floor vault immediately inside. Load the roof of the buttress with extra mass to help change the direction of the forces - Roof Vaults (220). Recognize that these thick walls must be outside the main space of the room, below the main vault of the room - Floor-Ceiling Vaults (219), so that they help to buttress the horizontal forces generated by the main vault of the ceiling. When you lay out columns and minor columns, put a column at the corner of every thick wall, so that the wall space, like other social spaces, becomes a recognizable part of the building structure - Columns at the Corners (212).
Alexander, Christopher. A Pattern Language: Towns, Buildings, Construction. Oxford University Press, 1977, p. 983.