Construction in timber and brick
- Also called:
- building construction
Timber construction underwent slow development in this period. Scandinavian stave churches of heavy timber were built from the 11th through the 14th century, prior to the triumph of the stone church, and about 30 have survived to the present day. In western Europe, particularly from the 14th century onward, half-timber construction emerged as a new form of house building. The continental type had a frame of squared timbers, with vertical posts spaced about one meter apart and horizontal girts spaced at the same distance; diagonal braces were run through the outside walls for lateral stability. The roof beams spanned between the ridgepole and the walls; floor beams were supported on the walls and interior partitions. The English half-timber frame was similar, but it eliminated the horizontal girts and diagonal bracing by using closely spaced verticals about one-half meter apart. In both systems the space in the outside wall was filled with an enclosure material to impart added rigidity to the frame; brick or wattle and daub were often used. All the timbers of the frame were attached together by elaborate dovetail, or mortise-and-tenon, joints. Half-timber framing would remain the standard way of building with wood in Europe until the 19th century. There was also considerable use of heavy timber for the roofs and floors of masonry buildings, which was influenced by shipbuilding technology. A particular instance of this is the English hammer-beam roof, which was a kind of corbeled truss that could span quite long distances. The roof of King Richard II’s Westminster Hall in London (1402), with a 21-meter (70-foot) span, is an excellent example of this type.
Fired brick began to be made again in Europe in the 14th century, preceded in many areas by the use of salvaged Roman brick. The 14th-century bricks were not as precise as the Roman and were often distorted in firing. Therefore, large lime-mortar joints were needed for regular course lines. Bricks became nearly standardized at something close to the present size, about 20.3 × 9.5 × 5.7 centimeters (8 × 3.75 × 2.25 inches), and bonding systems based on this approximately 2:1 proportion were developed. These bonding patterns reduced continuous vertical mortar joints, because the mortars were of substantially lower strength than the bricks and vertical joints could form planes of weakness in the walls where cracks might develop. The best bonding pattern was English bond, in which all the bricks in each course overlapped the ones below and vertical joints were entirely eliminated. Brick remained quite expensive because of the cost of the fuel needed to fire it, and it was used mainly where there was no readily available stone. In the late medieval period and mostly in northern Europe, brick was adapted to Gothic stone forms to build so-called hall churches, with naves and aisles of equal height.
Building services
Although Roman hypocaust heating disappeared with the empire, a new development in interior heating appeared in western Europe at the beginning of the 12th century: the masonry fireplace and chimney began to replace the central open fire. The large roof openings over central fires let in wind and rain, so each house had only one and larger buildings had as few as possible. Therefore, heated rooms tended to be large and semipublic, where many persons could share the fire’s warmth; the roof opening did not effectively remove all the smoke, some of which remained to plague the room’s occupants. The chimney did not let in much air or water and could remove most of the smoke. Although much of the heat went up the flue, it was still a great improvement, and, most significantly, it could be used to heat both small and large rooms and multistory buildings as well. Houses, particularly large ones, were broken up into smaller, more private spaces each heated by its own fireplace, a change that decisively altered the communal lifestyle of early medieval times.
The Renaissance
Reintroduction of dome construction
The waning of the cathedral crusade in the late 14th century led to a decline in the International Gothic style practiced by the master masons. In this period the emerging nation-states of Europe began to compete with the church as centers of power. To these new nations, the Roman Empire was the model nation-state, and it seemed appropriate that they use Roman building forms as symbols of their power—particularly the round arch, the vault, and, above all, the dome, following the powerful example of the Pantheon. From 1350 until 1750 much of building technology was focused on the domed church, which developed as a symbol not only of religious belief but also of national and urban pride. There was a conscious rejection of Gothic forms in favor of the ideological appeal of Rome. This attitude led to a split between the processes of design and construction and to the appearance of the first architects (a word derived from the Greek architekton, meaning a chief craftsman), who conceived a building’s form, as opposed to the builder, who executed it. The first building in which the designer and the builder were separate persons was the Campanile, or bell tower, of the cathedral of Florence. The design was made by the painter Giotto and constructed by cathedral masons from 1334 to 1359.
The cathedral of Florence itself had been begun in the Gothic style by Arnolfo di Cambio in 1296. But in 1366 the City of Florence, following the advice of certain painters and sculptors, decided that the Gothic should no longer be used and that all new work should follow Roman forms, including an octagonal dome 42 meters (138 feet) in span to be built at the east end of the nave. The dome was not built until the early 15th century, when Filippo Brunelleschi, a goldsmith and sculptor, began to make statues for the cathedral. Gradually he became interested in the building itself and built some smaller parts of it. In about 1415 he prepared a design for the dome that he daringly proposed to build without the aid of formwork, which had been absolutely necessary in all previous Roman and Gothic construction. He built a 1:12 model of the dome in brick to demonstrate his method; the design was accepted and built under his supervision from 1420 to 1436. Brunelleschi was thus the first real architect to conceive the building’s form and the methods to execute it and to guarantee its performance; he pointedly refused membership in both the masons’ and carpenters’ guilds. Brunelleschi’s dome consists of two layers, an inner dome spanning the diameter and a parallel outer shell to protect it from the weather and give it a more pleasing external form. Both domes are supported by 24 stone half arches, or ribs, of circular form, 2.1 meters (7 feet) thick at the base and tapering to 1.5 meters (5 feet), which meet at an open stone compression ring at the top. To resist outward thrust, tie rings of stone held together with metal cramps run horizontally between the ribs. There are also tie rings of oak timbers joined by metal connectors. The spaces between the ribs and tie rings are spanned by the inner and outer shells, which are of stone for the first 7.1 meters (23 feet) and brick above. The entire structure was built without formwork, the circular profiles of the ribs and rings being maintained by a system of measuring wires fixed at the centers of curvature. Brunelleschi obviously understood enough about the structural behavior of the dome to know that, if it were built in horizontal layers, it would always be stable and not require timber centering. He also designed elaborate wooden machines to move the needed building materials both vertically and horizontally. Having all but equaled the span of the Pantheon in stone, Brunelleschi was hailed as the man who “renewed Roman masonry work”; the dome was established as the paragon of built form.
The next great dome of the Renaissance was that of St. Peter’s Basilica in Rome, begun by Pope Julius II in 1506. The technology was very similar to that of Brunelleschi, and the diameter is nearly the same. The dome’s design went through many changes and extended over a period of nearly 80 years. The major contributors to the design were the painter and sculptor Michelangelo, who served as architect from 1546 to 1564, and the architects Giacomo della Porta and Domenico Fontana, under whose direction it was finally built during the 1580s. The dome was considerably thinner than that of Florence and was reinforced by three tie rings made of continuous iron chains. It developed numerous cracks, and in the 1740s five more chains were added to further stabilize it. Since the dome used a proven technology, most of the design was done on paper with drawings.
Another large dome of this period was that of St. Paul’s Cathedral in London, which was built from 1675 to 1710 by the English architect Sir Christopher Wren. In the early stages of the design process only two physical models were used; later efforts included extensive drawings and apparently also mathematical modeling with numerical calculations. Wren had begun his career as a mathematician and physical scientist and was professor of astronomy at Oxford from 1661 to 1673 before becoming a full-time architect. With this background he was thus able to profit from the first theoretical determination of the catenary curve as the most efficient profile of the arch and dome, which was published by the Scottish mathematician David Gregory in 1697. Wren’s solution to the dome, which has a diameter of 34.5 meters (113 feet), was a series of three nested shells, of which the middle one is the true structure. This middle dome is built of brick in a nearly conical catenary form, owing to the large concentrated load of the lantern on top, and constrained by iron chains; it supports a triangularly braced timber framework to which is attached the exterior surfacing of lead sheets. Within the middle dome is a shallower catenary dome that carries only its own weight and serves as a ceiling for the interior space. Wren’s concealed structure, to which were applied the desired internal and external forms, has become a standard architectural technique.
Revival of Roman technics and materials
In addition to Roman forms in masonry, the Renaissance recovered other Roman technologies, including timber trusses. Giorgio Vasari used king-post timber trusses for a 20-meter (66-foot) span in the roof of the Uffizi, or municipal office building, in Florence in the mid-16th century. At the same time, the Venetian architect Andrea Palladio used a fully triangulated timber truss for a bridge with a span of 30.5 meters (100 feet) over the Cimone River. Palladio clearly understood the importance of the carefully detailed diagonal members, for in his diagram of the truss in his Four Books on Architecture he said that they “support the whole work.” The tension connections of the timber members in the truss were joined with iron cramps and bolts.
Trussed spans in the range of 20–26 meters (65–85 feet) became fairly common in building roofs. In 1664 Wren used timber trusses with a span of about 22 meters (73 feet) in the roof of the Sheldonian Theatre at Oxford. But a precise theoretical understanding of the truss, and major use of it in buildings, would not come until the 19th century.
Another Roman material that was revived and much improved in the Renaissance was clear glass. A new technique for making it was perfected in Venice in the 16th century. It was known as the crown glass method and was originally used for making dinner plates. Glassblowers spun the molten glass into flat disks up to a meter in diameter; the disks were polished after they had cooled and were cut into rectangular shapes. The first record of crown glass windows is their installation in double-hung counterweighted sliding-sash frames, at Inigo Jones’s Banqueting House in London in 1685. Large areas of such glass became common in the 1700s, pointing the way toward the great glass and iron buildings of the 19th century.
The efficiency of interior heating was improved by the introduction of cast-iron and clay-tile stoves, which were placed in a free-standing position in the room. The radiant heat they produced was uniformly distributed in the space, and they lent themselves to the burning of coal—a new fuel that was rapidly replacing wood in western Europe. When European builders had recovered the technology of the Classical world in brick, stone, and timber, a stable plateau was reached in the development of the building arts; these materials and technics were well suited to the churches, palaces, and fortifications that their patrons required. The Industrial Revolution, however, brought new materials and the demand for new building types that completely transformed building technology.