A Pattern Language

Floor and Ceiling Layout (210)

Problem

Again, the basic problem is to maintain the integrity of social spaces in the plan.

Solution

Draw a vault plan, for every floor. Use two-way vaults most often; and one-way barrel vaults for any spaces which are more than twice as long as they are wide. Draw sections through the building as you plan the vaults, and bear the following facts in mind:

  1. Generally speaking, the vaults should correspond to rooms.
  2. There will have to be a support under the sides of each vault: this will usually be the top of a wall. Under exceptional circumstances, it can be a beam or arch.
  3. A vault may span as little as 5 feet and as much as 30 feet. However, it must have a rise equal to at least 13 percent of its shorter span.
  4. If the edge of one vault is more than a couple of feet (in plan) from the edge of the vault below it—then the lower vault will have to contain an arch to support the load from the upper vault.

… Efficient Structure (206) tells us that the spaces in the building should be vaulted so that the floors and ceilings can be made almost entirely of compression materials. To lay out the floor and ceiling vaults, we must fit them to the variety of ceiling heights over individual rooms - Ceiling Height Variety (190) and, on the top story, to the layout of the roof vaults - Roof Layout (209).

Put a Perimeter Beams (217) on all four sides of every vault, along the top of the bearing wall, or spanning openings. Get the shape of the vaults from Floor-Ceiling Vaults (219) and as you lay out the sections through the vaults, bear in mind that the perimeter beams get lower and lower on higher floors, because the columns on upper stories must be shorter (top floor columns about 4 feet, one below top 6 feet, two below top 6 to 7 feet, three below top 8 feet) - Final Column Distribution (213). Make sure that variations in floor level coincide with the distinctions between quiet and more public areas - Floor Surface (233). Complete the definition of the individual spaces which the vaults create with Columns at the Corners (212). Include the smallest vaults of all, around the building edge, in Thickening the Outer Walls (211)

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