1868.]. Practical Carpentry and Joinery. 251 square joints. This portion of the roof is invariably covered with slate, when- ever such material can be obtained ; and where it is not procurable, shingles are often substituted. When the form of the roof is curved, the slates are usualty of a smaller size than those for an ordi- nary straight roof. The first course of slate is laid immediate^ along the upper edge of the gutter ; and below this, com- mencing at the eave, including the gut- ter, is covered with tin, which extends up the roof, about four inches beneath the slates. The upper roof is often raised to a sufficient height to admit of slates or shingles being used. In such case, the pitch should never be less than 21 de- grees ; and more should be given where the design will permit. In all instances, when roofs of this kind are constructed, it is necessary to line inside with rough boards, which must be cross-cleated with furring laths, at least one inch, or one and a-quarter inches thick. These furring laths should not be less than sixteen inches between centres, to admit four nails to the plas- tering laths which are usually cut four feet long. These spaces for nailing are very important, both as a convenience to the plasterer, and also an economy in the material. This mode of finish not only strengthens the frame-work of the roof — which is a very essential mat- ter, particularly when the building is exposed on all sides — but in summer it also prevents the heat from penetrating ; and renders these apartments quite as cool and as pleasant as though the walls were constructed of stone or brick. There is another style of finish, less expensive, it is true, and, perhaps, com- paring favorably with the one last men- tioned, as to its effect on the tempera- ture of the rooms, but still not possess- ing the same amount of firmness and stability. This is to lath and plaster one coat directly on the studding ; and after it is partially set, to nail the fur- ring laths upon this, in the manner we have just described for the boarding. This mode, not so good for the frame- work, is decidedly the best adapted sim- ply for ceilings, in which it creates firm- ness, prevents the cracking in the plas- ter, which is occasioned by the irregu- lar shrinkage of the joists; and also deadens sound between the stories. There should always be reserved a good-sized space for a loft, above the rooms that are constructed within a roof of this description. When the building is of greater width than can be spanned by single joists, they should be secured together. One very simple plan of doing this is, to nail a cleat along the side, five or six feet long. This, in any ordinary build- ing will answer the purpose of prevent- ing the spreading, by any lateral press- ure there might be from the roof, aided by the influence of the wind. There are numerous other methods of binding joists ; but we shall treat of them in a future number, when we introduce struc- tures of a more ponderous and exten- sive character. The one we have given is the simplest in common use. The profile and face of the bracket beneath the cornice, as indicated, is constructed with three separate pieces in thickness ; the core or centre-piece is three inches, or as thick as a three-inch plank will produce. The sides are each one and a-half inches, pierced through to the required form ; and nailed securely to the sides of the centre-piece. The face is frequently advanced half an inch beyond that of the centre-piece, to form a sinking, and to blind or conceal the joints. We propose, in the next description of a roof of this kind, to show, in detail, the construction of the dormer windows and balustrades, and their connection with the roof. In order to have them more easily comprehended, and be of more practical benefit to mechanics, we shall present detail drawings, on a large scale and in regular order, of every part, from the simplest up to the most com- plicated and elaborate.
