KEYWORDS:

SHORT DESCRIPTION:

• While vaults and domes are self-supporting structural forms when completed, they normally need support and centering while under construction. This usually involves first building an identical vault in wood over which the masonry vault rests, until complete and dried.

• In countries where timber is scarce, this type of vaulting is hardly advantageous. A system of building vaults and domes, without this framework, or shuttering, evolved in countries like Egypt and Iran.

• The drawings overleaf show the sequence of construction of a small house, which the founder members of Development Workshop and some friends built in New Gourna, Upper Egypt, in 1973. They worked as apprentices alongside two Nubian master masons, skilled in the techniques being used.

• The house was built with mud bricks and served, amongst other objectives, as a practical opportunity to master and evaluate the Nubian techniques of building without the use of shuttering, and to obtain a clear guide regarding the relationship of roof span to wall thickness and height for mud brick walls.

• The house stands amongst the buildings designed by Hassan Fathy, who revived this building technique in the 1940s (Bibl. 02.14).

Building Sequence of Experimental House in New Gourna, Upper Egypt (Illustrations by Development Workshop, Bibl. 24.03)

Walls built up to the level of the spring points of the vaults. End wall built up for vault to lean on. Inverted catenary form traced on end wall; Vault is completed; each course of bricks is less inclined, until vault is flush with side walls. Window openings built up with dry bricks - no mortar; Vault building with courses leaning towards end wall so that no formwork or shuttering is required; Walls built up. Arches built over dry brick in windows.

Small vault built in same way as large ones. Loose bricks removed from window openings; Pendentives completed, forming continuous course from which dome can be completed; Circular arches built over vaults to form a base for the dome; Brick courses of dome incline increasingly until dome is finished.

• Further information: Development Workshop (coordinating office in Canada), Box 133, 238 Davenport Road, Toronto, Ontario M5R IJ6, Canada, or (Europe office in France) B.P. 10 Montayral, 47500 Fumel, France.

New Developments

Arches constructed with old car tyres
(Bibl. 24.12)

Simple arches can be constructed over openings by using old car tyres as formwork. This was fried out on a project in India (1986) and found extremely easy to carry out. The sides of the opening, which has the width of the tyre, are erected up to the level at which the arch begins. The tyre is placed on a dry stack of bricks, such that the axis is in line with the top brick layer. The bricks should be laid alternately on each side of the tyre, since excessive load on one side can deform the tyre and distort the shape of the arch. Care must be taken that the lower edges of the bricks touch each other without leaving any gaps. Since the tyre is flexible, it can be removed with ease.

FIGURE

Catenary shaped dome

A catenary shaped template, which rotates around a vertical axis at the centre of the dome, is used to place the bricks with great accuracy to form a curvature which permits only compressive forces to act within the structure. This gives a more stable dome construction than hemispherically shaped domes.

This innovative construction method was developed and tested in 1987 at the Research Laboratory for Experimental Construction, Kassel College of Technology, Federal Republic of Germany, headed by Prof. Gernot Minke.