The building plan. The first task of an architect who sets out to design a house is to draw up a plan, i.e. a horizontal projection of the walls and the principal parts of the building. The plan must always give a clear picture of the number, shape and size of the rooms required in the given case, of their mutual arrangement and overall grouping.
The shape of rooms in plan can vary widely; it depends both on their purpose and on the best possible arrangement of rooms next to one another
Rectangular form. For living spaces the form used most often is rectangular, not overly elongated. It is the most advantageous both structurally and in practical terms, allowing adjacent rooms of different sizes to be laid out conveniently and making economical use of space in the building itself and in the arrangement of furniture.
The impression produced by a rectangular room, regardless of its size, will always be pleasing to the eye, provided that certain proportions between the sides are observed and a height corresponding to them is chosen.
The recommended ratio of the sides is expressed by the formula:
b < a < 2 b; or
a > b > ½ a,
i.e. the length of the room (a), being greater than its width (b), must at the same time be less than twice the latter. And conversely, the width of the room, being less than its length, must be greater than half the latter.
Within these limits an infinite number of variations in the shape of the rectangle is possible, regardless of its absolute size, so that it is not difficult to avoid monotony when a house contains a large number of rectangular rooms.
An elongated rectangle is used more often for secondary rooms, for galleries, corridors and the like.
Square form. A less advantageous form for a living space is the square. It already causes difficulties in drawing up the overall plan, a subdivision of which — into squares alone is not always possible. The regular shape of the room also complicates the arrangement of furniture.
Thus square rooms are suitable only when they are of more considerable size, or in particular cases, for example: for drawing rooms, handsome studies and so on, chiefly however to obtain variety in a series of rectangular rooms.
And yet the dull impression produced by a square room makes one resort to artificial means of enlivening its overall appearance. For this purpose wide windows, special finishes of the walls and ceiling, ornate fireplaces and the like are used; bay windows and deep niches are also introduced, in an effort to soften the severe form of the plan itself.
The advantage of the square is that the sum of its sides is smaller than the sum of the sides of a rectangle of equal area, and consequently the walls of a square room will cost less than those of a rectangular one with the same floor area and height.
Circular form. For the same reason a circle is still more advantageous, its perimeter being approximately 11.3% smaller than the sum of the sides of a square of equal area.
However, a circular room in a dwelling house proves inconvenient and is used only by way of exception, since in combination with other rooms it wastes a great deal of space, while the construction of the ceiling, floor, windows and doors becomes considerably more complicated and more expensive. Finally, the arrangement of furniture here is a far from easy matter. All these reasons lead one to avoid in ordinary dwelling houses circular as well as elliptical rooms and to use them only in wealthier houses for ballrooms, lavish dining rooms, vestibules and so on, giving such rooms a correspondingly lavish finish.
With a large radius of a circle or ellipse the curvature of their perimeter naturally decreases, and so do the inconveniences associated with it, but the rooms themselves become disproportionately large and costly, and therefore again prove of little use for ordinary dwelling houses.
As for polygonal rooms in plan, they all have shortcomings similar to those listed above. A room in the form of an octagon proves more suitable than the others, yet it too is used only by way of exception, because its short sides considerably hinder the arrangement of furniture. And yet polygonal rooms, like circular ones, may be appropriate where it is necessary to achieve a degree of variety in a series of rooms similar to one another in size and shape.
