fig. 245 we illustrate what is known as the "curb roof, or, from the name of its designer, the "mansard " roof, by which name it is better known on the Continent, where it is very widely adopted, as by its use a good apartment may be placed in the roof, being lighted by windows, as a, fig. 245, or lighted by a "dormar window," which see. Another arrangement of "curb" roof is shown in fig. 246, in which doors a b are placed in the partition, the tie beam b of the upper truss being supported by a central post c. In Plate XXXIX., fig. 3, another arrangement is given, the vertical posts or studding, as a a, forming the sides of the apartment or room in the roof, are called " ashlets," and sometimes puncheons, although this term is properly applied to the short posts of a partition above the door.
" Conical roofs" are but seldom used, being chiefly for kilns, horse-thrashing machine houses, circuses, gas works, etc. One form is shown in fig. 247, in which the upper diagram gives a sectional elevation - a a the walls, b b a tie beam stretching across the diameter of the circular building c c, the rafters, ring, or timber strutting d d are placed all round, and on these the rafters rest, all terminating at the apex of the cone. The outer circular wall is shown at e e in the diagram, f and g representing the lines of purlins d d, h h the principal rafters, i i is part of a purlin, j j a principal rafter going from wall e to apex g, h h a common rafter going from wall e to second purlin g, i one stretching from h to g, and k l from e to h. An example of a conical roof for a circus is given in figs. 1, 2, 3, and 4, in Plate XIX, being that designed by M. Hittoff for the Napoleon Circus in Paris, and which we have reduced from drawings given in the Encyclopcedia of Architecture, published at 13 Rue Bonaparte, by M. Bance. Pig. 1 is the upper part with ventilator a a and flag-staff b b, cc the upper part of one of the trussed girders, fig. 2, d the lower part, e the wall, figs. 3 and 4 two parts of the plan of one of the girders with intervening rafters.
These are met with very frequently on the Continent, and in districts where the snowfalls are heavy, so that the snow may be quickly dislodged. In Plate XXXIX., in figs. 1 and 2, and fig. 1, Plate XL., examples of Continental high-pitched roofs are given. In figs. 248 and 249 we give diagram of Gothic or high-pitched roofs - the beam a a, in fig. 249, being usually, in this class of roofs, called a "hammer beam " in place of a tie beam. In fig. 250 we illustrate a low-pitched, and in fig. 251 a flat, roof. When the attic or roof chambers are lighted by windows, the faces of which are vertical, the arrangement is called a dormer window, as in fig. 252, where a is a side and b a front view.
Fig. 253 illustrates a section showing at a a part of the common rafter, from which the window rises, b b cross-piece let into the rafter, d vertical post, e ridge-piece, f f small rafters.
These are generally employed to light attic apartments or staircases, being placed in the slope of the roof, as in fig. 254, in which a a is the rafter, 6 the opening which may be the width of the space between two or more rafters; the opening is lined with wood towards the apartment, and the glass is placed in a frame c c which is hinged. In fig. 254, a plain skylight is shown at e e, the glass f is merely fixed in the frame (in one or two divisions, as at g g), at upper side of opening e e, the lining of which is fixed to the rafters d d; at h h a staircase skylight outside elevation is shown. Fig.
255 gives diagrams illustrating a conical-shaped roof or skylight at a, lighting a staircase b; c c d, another form lighting the staircase at e.
We have already, in preceding figures of Roofs, illustrated the simpler forms of gutters, in which hollow or concave troughs - as they may be called - of metal are fastened to the ends of the common rafters, which are made to project beyond the wall for that purpose. In fig. 256 we illustrate what is called a "bridged gutter" a, which is formed behind the wall b b; the rafters d d butt against a wall plate c, and the gutter a a is carried by the bridging piece f} in which is laid the boarding e e, which is covered either with lead or zinc. In fig. 257, a a is the tie beam, which is supported in the centre by a trussed partition b; c c, the rafters, which butt against the plate of timber d; e, the bridging piece, which carries the gutter boarding f. In fig. 258 the gutter is outside the wall a a, and is carried by a short projecting piece of timber, termed a " cantaliver," b b, built into the wall at one end, and more or less enriched, c is the common rafter, d the wall plate, and e the gutter. In figs. 259, 260, and 261, other forms are given.
Brackets are sometimes used in place of cantalivers, although these may be and are often called enriched cantalivers; a form of bracket is shown in fig. 262, the lower end of which rests on a small stone corbel a, tailed or built into the wall b b; c c a piece of timber moulded in front and also built into the wall, is connected with the corbel a a by an angular part d d. In fig. 263 part of another design for a bracket is shown, the part between a a being either left open or filled up with solid timber, or with ornamental work as in figs. 264 and 265.
The gabled ends of roofs are ornamented with a variety of designs (see figs. 266, 267, 268, and 269 as examples) formed in wood and termed barge boards; their primary use is to cover the ends of the roof timber which would otherwise look unsightly. In some instances these ends are covered with a fascia board, that is a plain board as in c c, fig. 269, moulded in the edges. In fig. 269 the barge board is often terminated by a finial, termed a "hip knob," as a 6, against which the barge or fascia boards terminate, as at c c. Roofs in place of being terminated by gables, at both ends as c - plan in b, fig. 270 - are arranged as shown at c d, and which have their ends c d at the same angle as the sides e f, are termed "hip roofs" or "hipped roofs;" the short rafters, as g g in fig. 271, are termed "jack" or hip rafters, and their lower part rests upon an angular part (see "Joints" in Timber Work), called an " angle tie," and sometimes upon a piece borne by this, called the " dragon beam," or "dragon tie." When a hipped roof does not terminate in a ridge, as in fig. 271, at h as at i, but in a flat space as j, in elevation at k, it is called a " pavilion" or "coach-house roof."