Of course there are dozens of other ways to make a roof vault. Other versions include ordinary barrel vaults, lamella structures in the form of barrel vaults, elongated geodesic domes (built up from struts), vaults built up from plastic sheets, or fiberglass, or corrugated metal.
But, in one way or another, build your roofs according to the invariant defined below, remembering that it lies somewhere in between the Crystal Palace, the stone vaults of Alberobello, mud huts of the Congo, grass structures of the South Pacific, and the corrugated iron huts of our own time. This shape is required whenever you are working with materials which are in pure compression.
Obviously, if you have access to wood or steel and want to use it, you can modify this shape by adding tension members. However, we believe that these tension materials will become more
| 220 ROOF VAULTS |
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| Exferhnental roof vaults.and more rare as rime goes on and that the pure compression shape will gradually become a universal.Therefore: |
Build the roof vault either as a cylindrical barrel vault, or like a pitched roof with a slight convex curve in each of the two sloping sides. Put in undulations along the vault, to make the shell more effective. The curvature of the main shell, and of the undulations, can vary with the span; the bigger the span, the deeper the curvature and undulations need to be.
Leave space for dormers at intervals along the vault—dormer windows (231), and build them integral with it. Finish the roof with roof caps (232). And once the vault is complete, it needs a waterproof paint or skin applied to its outer surface—lapped outside walls (234). It can be painted white to protect it against the sun; the undulations will carry the rainwater. . . .
within the main frame of the buildingy fix the exact 'positions for openings—the doors and the windows —and frame these openings.
221. NATURAL DOORS AND WINDOWS
222. LOW SILL
223. DEEP REVEALS 2 24. LOW DOORWAY
225. FRAMES AS THICKENED EDGES
IO45
II LOCAL TRANSPORT AREAS
Noise
Danger
111 health
Congestion
Parking problem
Eyesore
The first two are very serious, but are not inherent in the car; they could both be solved, for instance, by an electric car. They are, in that sense, temporary problems. Danger will be a persistent feature of the car so long as we go on using high-speed vehicles for local trips. The widespread lack of exercise and consequent ill health created by the use of motor-driven vehicles will persist unless offset by an amount of daily exercise at least equal to a 20 minute walk per day. And finally, the problems of congestion and loss of speed, difficulty and cost of parking, and eyesore are all direct results of the fact that the car is a very large vehicle which consumes a great deal of space.
The fact that cars are. large is, in the end, the most serious aspect of a transportation system based on the use. of cars, since it is inherent in the very nature of cars. Let us state this problem in its most pungent form. A man occupies about 5 square feet of space when he is standing still, and perhaps 10 square feet when he is walking. A car occupies about 350 square feet when it is landing still (if we include access), and at 30 miles an hour, when cars arc 3 car lengths apart, it occupies about IOOO square feet. As we know, most of the time cars have a single occupant. This means that when people use cars, each person occupies almost 100 times as much space as he does when he is a pedestrian.
If each person driving occupies an area 100 times as large as he does when he is on his feet, this means that people are 10 times as far apart. In other words, the use of cars has the overall efect of spreading people out, and keeping them apart.
The effect of this particular feature of cars on the social fabric is clear. People are drawn away from each other; densities and corresponding frequencies of interaction decrease substantially. Contacts become fragmented and specialized, since they are localized by the nature of the interaction into well-defined indoor places—the home, the workplace, and maybe the homes of a few isolated friends.
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| IO46 |
22 1 NATURAL DOORS AND WINDOWS**
. . . imagine that you are now standing in the built-up frame of a partly constructed building, with the columns and beams in
place-BOX COLUMNS (216), PERIMETER BEAMS (2I7). You
know roughly where you want doors and windows from zen VIEW (134), STREET WINDOWS (164), WINDOW PLACE (l8o), WINDOWS OVERLOOKING LIFE (192), CORNER DOORS (196). Now you can settle on the exact positions of the frames.
Finding the right position for a window or a door is a subtle matter. But there are very few ways of building which take this into consideration.
In our current ways of building, the delicacy of placing a window or a door has nearly vanished. But it is just this refinement, down to the last foot, even to the last inch or two, which makes an immense difference. Windows and doors which are just right are always like this. Find a beautiful window. Study it. See how different it would be if its dimensions varied a few inches in either direction.
Now look at the windows and doors in most buildings made during the last 20 years. Assume that these openings are in roughly the right place, but notice how they could be improved if they were free to shift around, a few inches here and there, each one taking advantage of its own special circumstances—the space immediately inside and the view outside.
It is almost always a rigid construction system, combined with a formal aesthetic, which holds these windows in such a death grip. There is nothing else to this regularity, for it is possible to relax the regularity without losing structural integrity.
It is also important to realize that this final placing of windows and doors can only be done on site, with the rough frame of the building in position. It is impossible to do it on paper. But on the site it is quite straightforward and natural; mock up the openings with scraps of lumber or string and move them around until they feel right; pay careful attention to the organization of the view and the kind of space that is created inside.
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| Getting it just right. |
As we shall see in a later pattern—small panes (239), it is not necessary to make the windows any special dimensions, or to try and make them multiples of any standard pane size. Whatever dimensions this pattern gives each window, it will then be possible to divide it up, to form small panes, which will be different in their exact shape and size, according to the window they are in.
However, although there is no constraint on the exact dimension of the windows, there is a general rule of thumb, which will make window sizes vary: Windows, as a rule, should become smaller as you get higher up in the building.