Slab (architecture)

“ But it does suggest, at least by a play upon words in several languages, a current climate of taste which favours béton brut—naked concrete—and rough, usually rather dark-coloured, materials. Bricks, pre-cast slabs with a coarse aggregate in relief, or even stone masonry of rubble or quarry-faced granite, with rather heavy trim of raw or varnished wood and wrought iron, are widely preferred to the slicker, more highly finished elements that are the natural product of the increasing industrialization of the building crafts. ”

“ From the first sun-dried bricks, sometimes combined with stone, were the chief materials used, even the grander structures of the best period such as the huge palaces and halls were of plastered brickwork, stone having been as a general rule reserved for such works as temples, theatres, and triumphal arches. Concrete was also largely employed, and timber in many cases was turned to account for roofing. The most distinctive peculiarity of the architecture of the Romans is the vaulted roof, which they employed in an infinite variety of ways, introducing it at every possible opportunity. ”

“ The use of stone for building might have arisen in many places independently. But megalithic architecture is something [145] much more than this. It is the use of great stones in certain definite and particular ways. We have already examined what may be called the style of megalithic architecture and found that the same features are noticeable in all countries where these buildings occur. In each case we see a type of construction based on the use of large orthostatic slabs, sometimes surmounted by courses of horizontal masonry, with either a roof of horizontal slabs or a corbelled vault. ”

“ The inner thickness consists of the framework of the coffers, which is of brick, and the filling-in of the coffers, which is of rubble or concrete. This would form the centering on which the outer shell was built, which is a curious tissue of arches, each rising from the crowns of those below it, and so disposed as to concentrate the pressure upon points in the wall which intervene between the cells. ”

“ Plaster, terra-cotta, paint, tiles, wood, iron, and brick, even when united with all the skill of the most exquisite art, cannot long resist the rapid wear and tear of such a humid climate as ours. Those unsubstantial structures, with all their dazzling incrustations, are passed or passing from the earth: nothing is lasting but hard massive stone, impenetrable cement, and scientific combinations. ”

“ The walls are uniformly thick, and often of granite or of stone, though brick is also met with; e.g. some of the smaller pyramids are built entirely of brick. In all probability the walls of domestic buildings were to a great extent of brick, and less thick than those of the temples; hence they have all disappeared.
The surface of walls, even when of granite, was usually plastered with a thin fine plaster, which was covered by the profuse decoration in colour already alluded to. ”

“ The construction, though massive and real, is always hidden, and does not enter yet as an ornamental motive in the compositions of the architect.
It is worthy of observation, that one of the mouldings of Egyptian architecture seems to be explained by the same ancient custom of encrusting brick buildings with stone slabs, which we have remarked on the Assyrian monuments. I allude to the torus moulding which encloses the external walls of edifices. It served to hide the joints of the slabs which covered the internal work. ”

“ The ornaments are composed of small square blocks of stone, cut to the depth of about one to one and a half inches, apparently with the most delicate instruments, and inserted by a shaft in the wall. The wall is made of large and uniformly square blocks of limestone, set in a mortar which appears to be as durable as the stone itself. In the ornamental borders of this building I could discover but little analogy with those known to me. The most striking were those of the cornice and entablature, chevron and the cable moulding, which are characteristic of the Norman architecture. ”

“ The Walls of such buildings as have come down to us are, it may be well understood, strong, since the most recent of this round-arched series of buildings must be about seven hundred years old. Fine masonry was not much employed till the time of the Normans, but the Roman plan of building with bricks or rubble and casing the face of the walls with marble or mosaic, or at least plaster, was generally followed. The walls are carried up as gables and towers to a considerable extent (Fig. 179) , especially in Western countries. ”

“ Some buildings were vaulted in every storey, giving good examples of really fireproof construction; others were fireproof through one or two storeys, and timbered above; and others, again, had timber floors throughout. In secular structures we find trabeated architecture in its truest form—not stone beams, which, when extended beyond very narrow limits, go against the nature of the material, but real beams of wood, used in a thoroughly sensible and constructive manner. ”

“ It is not so much that the walls are thin, as that they have disappeared: there are no walls—only a series of piers dividing windows, the opening filled with glass being much greater, if measured along a horizontal line running through the windows, than is the extent of the solid masonry. You see at once wherein there is an excuse for the saying “a wall of glass with a roof of stone.” But there is more than this: the primary object of the designer has been to treat his construction as the main inspiration of his design. ”

“ He who wishes to avoid such a disaster should leave a cavity behind the facings, and on the inside build walls two feet thick, made of red dimension stone or burnt brick or lava in courses, and then bind them to the fronts by means of iron clamps and lead. For thus his work, being no mere heap of material but regularly laid in courses, will be strong enough to last forever [52] without a flaw, because the beds and builds, all settling equally and bonded at the joints, will not let the work bulge out, nor allow the fall of the face walls which have been tightly fastened together. ”

“ The walls of the cella itself should be thick in proportion to its size, provided that their antae are kept of the same thickness as the columns. If the walls are to be of masonry, let the rubble used be as small as possible; but if they are to be of dimension stone or marble, the material ought to be of a very moderate and uniform size; for the laying of the stones so as to break joints will make the whole work stronger, and their bevelled edges, standing up about the builds and beds, will give it an agreeable look, somewhat like that of a picture. ”

“ Vaulted roofs for example are comparatively rare, and domes, even when the inner dome is of brickwork or masonry, have their outer envelope of carpentry. A disuse of brick and rough masonry, or rather a constant effort to conceal them from view, is a distinctive mark of Renaissance work. The Roman method of facing rough walls with fine stone was resorted to in the best buildings. In humbler buildings plaster is employed.
Renaissance architects made very free use of plaster. Inside and out this material is utilised, not merely to cover surfaces, but to form architectural features. ”

“ The construction was extremely simple. The heavy clay walls were faced with alabaster, burned brick, or enamelled tiles. The roofs were probably covered with stamped earth, and sometimes paved on top with tiles or slabs of alabaster to form terraces. Light was introduced most probably through windows immediately under the roof and divided by small columns forming mullions, as suggested by certain relief pictures. No other system seems consistent with the windowless walls of the ruins. ”

“ For when the tiles on the roof are broken or thrown down by the wind so that rainwater can leak through, this burnt brick coating will prevent the crude brick from being damaged, and the cornice-like projection will throw off the drops beyond the vertical face, and thus the walls, though of crude brick structure, will be preserved intact. ”

“ This wall was originally incrusted with rich marbles, and the great dome, adorned with deep coffering in rectangular panels, was decorated with rosettes and mouldings in gilt stucco. The dome appears to have been composed of numerous arches and ribs, filled in and finally coated with concrete. A recent examination of a denuded portion of its inner surface has convinced the writer that the interior panelling was executed after, and not during, its construction, by hewing the panels out of the mass of brick and concrete, without regard to the form and position of the origin skeleton of ribs. ”

“ Marble wall-slabbing needs very careful fixing, and should be well supported by a sufficient number of cramps at a little distance from the wall, leaving a space of about half an inch at the back of the slab. ”

“ Dimension stone, flint, rubble, burnt or unburnt brick,--use them as you find them. For it is not every neighbourhood or particular locality that can have a wall built of burnt brick like that at Babylon, where there was plenty of asphalt to take the place of lime and sand, and yet possibly each may be provided with materials of equal usefulness so that out of them a faultless wall may be built to last forever. ”

“ The stone ribs which spring directly from the uprights with but the slightest pretense at vaulting shafts in little{122} round mouldings with slightly marked capitals, are really the arches which carry the whole stone structure of the roof. The great pendants into which these ribs disappear, and which themselves form the basis of the fan-vaulting system, are of course without constructional value. The roof is to be taken as an elaborate piece of geometrical carving, ingeniously arranged in the semblance of a constructional work ”

“ A thin facing of marble or other ornamental solid or even plastic material may be applied to the face of the slabs during the process of casting, thus enabling the work to be finished as it is carried up, or a key may be formed on the face of the slab to enable the structure to be plastered afterward. ”

“ The masonry was usually laid up without cement and clamped with metal; there is no filling in with rubble and concrete between mere facings of cut stone, as in most modern work. When the only available stone was of coarse texture it was finished with a coating of fine stucco, in which sharp edges and minute detail could be worked.
The details were, in the best period, executed with the 59 most extraordinary refinement and care. The profiles of capitals and mouldings, the carved ornament, the arrises of the flutings, were cut with marvellous precision and delicacy. ”

“ Next, lay the mixture of broken stone, bring on your gangs, and beat it again and again with wooden beetles into a solid mass, and let it be not less than three quarters of a foot in thickness when the beating is finished. On this lay the nucleus, consisting of pounded tile mixed with lime in the pro­portions of three parts to one, and forming a layer not less than six digits thick. On top of the nucleus, the floor, whether made of cut slips or of cubes, should be well and truly laid by rule and level. ”

“ Walls, Towers, Columns.
Walls are usually thick and stand unbuttressed, and rarely have such slopes and diminutions of apparent thickness towards their upper part as are not uncommon in England. Base mouldings are not universal. The cornice, on the other hand, is far more cared for, and is made much more conspicuous than with us. In the brick buildings especially it attains great development. Above the cornice [Pg 128] a kind of ornamental parapet, bearing some resemblance to battlements, is common. ”

“ Street architecture in later Victorian days became a masquerade in building materials, since the design of the façade bears little or no relation to the hidden structure of steel framing by which our many-storied piles are held together, while, apparently, when there are shops on the ground floor the whole mass has the effect of playfully reposing upon the edges of great sheets of plate glass. ”

“ Over the portal a curved pediment is set against the entablature of the lower order, and the whole façade is crowned with a semicircular [152] pediment pierced with a large round opening and five smaller ones ranged on its semicircumference. The wall surfaces are incrusted with marble panelling set with disks and lesser panels of cruciform and rectangular shapes in faintly coloured marbles, and the whole building is a marvel of excellence [153] in mechanical execution. ”

“ These causes have led to the erection of buildings of excessive height (Fig. 224) ; the more recent among them constructed with a framework of iron or steel columns and beams, the visible walls being a mere filling-in. To render a building of twenty stories attractive to the eye, especially when built on an irregular site, is a difficult problem, of which a wholly satisfactory solution has yet to be found. ”

“ The building is circular, with a noble dome, and a fine portico of sixteen pillars of oriental granite. There are no windows, the light being admitted by a circular aperture in the dome. The fine marble with which the walls were encrusted, and the brass which covered the roof, have long since disappeared; the bare bricks alone are left. ”

“ Since such very powerful kings have not disdained walls built of brick, although with their revenues and from booty they might often have had them not only of masonry or dimension stone but even of marble, I think that one ought not to reject buildings made of brick-work, provided that they are properly "topped." ”

“ Built of buff brick with tile roofs of medium pitch, the general effect is much quieter than that of the Latin American university cities with their tall ferro-concrete buildings, crisply shaped and distinguished both by a bold use of colour and the conspicuous incorporation of work by distinguished painters and sculptors. ”