This section is from the book "The Principles And Practice Of Modern House-Construction", by G. Lister Sutcliffe. Also available from Amazon: How Your House Works: A Visual Guide to Understanding & Maintaining Your Home.
The windows of a house have a very important influence on its comfort and health fulness. To some of the general principles of window design, attention has already been drawn in Chapter I. A few words must now be said on the practical details of their construction. The insertion of glass into grooves in the stonework of windows is now nearly obsolete, and deservedly so, on account of the lack of ventilation, and the number of cracked sheets of glass caused by the rigid framework, and the trouble of replacing them. It is usual nowadays to provide a wood or metal frame to receive the glass. Windows are of two principal classes, sach-windows and casements, and each class has its peculiar advantages and disadvantages ash-windows are peculiarly British in their origin and development, being seldom Been abroad. They are especially suitable for openings of considerable sue, but look clumsy when used in small mullioned windows. They are con-venient, easily made weather-proof (although somewhat apt to rattle in strong wind), and may be readily used for ventilation. On the other hand, they are somewhat intricate and apt to get out of order, and the outside of the glass is difficult to clean. Indeed so great is the trouble of cleaning, and so many accidents have occurred to persons standing on the window-sills for this purpose, that it is no wonder that inventors have turned their attention to the subject Numerous patents have been taken out for windows so arranged that the sashes can be reversed, and therefore cleaned from the inside of the room. In Glasgow, the building-regulations require all new sashes to he reversible, and other towns will doubtless follow the example before long. Reversible sashes may be hung in the ordinary way with cords and weights, or may be hung over pulleys so as to balance each other, thus dispensing with weights. Details of the National Accident Prevention Company's "weightless" window are given in Plate I\. In such windows the bottom sash necessarily rises when the top sash is lowered, and as it is frequently desirable that air should be admitted to the room only at the meeting-rails and top of the window, it becomes necessary to give a very deep bottom rail to the bottom sash and to fix a correspondingly deep fare-hoard inside, as shown in the section. A similar arrangement is, however, advantageous in ordinary sashes, as air can then be admitted at the meeting-rails only when desired, where it acquires an upward current; the risk of draughts is thereby reduced.
THE N.A.P. WEIGHTLESS REVERSIBLE WINDOW.
Into the details of ordinary sash-window it is not necessary to enter. One or two points, however, may be mentioned. The sills should be of oak or teak, and weathered and throated on the top; in the section in Plate IV. only one throating is shown, but another, immediately under the outer face of the bottom rail, is often formed, as in Plate V. The sills should be bedded in white-lead, and the joint is all the more weather-tight if a galvanized iron weather-tongue (about 1 inch by ¼ inch) is let into grooves cut in the under side of the wood sill and the upper side of the stone sill, and bedded in white-lead. The meeting-rails should be rebated at their junction, one method being shown in the illustration. If the vertical parting-beads between the sashes are of teak, there will be less likelihood of them swelling and of the sashes sticking fast. Red (yellow) deal is the wood most frequently used for the sashes themselves and the other parts of the frames, but in high-class buildings oak, mahogany, and other woods are preferred Weights may be of iron or lead, the latter being more expensive but less bulky. Sash-lines may be of hemp, flax, steel ribbon, or zinc, copper, or steel chains; hemp is coarse and cheap; superfine flax is a very good material, but for heavy sashes the steel and copper lines are the best. Cheap pulleys are wholly of iron; better ones are brass-bushed, while the most expensive have also brass faces and brass wheels. Sash-fasteners are of infinite variety, the simple screw-fastener being as safe as any, and having the merit of drawing the sashes tightly together and preventing rattling to some extent.
A combined sash-and-casement window is illustrated in Plate V. This is simple and weather-proof, and allows the glass to be cleaned inside the room. It is little more expensive than an ordinary sash-window, and combines with it the merits of a French casement. In the illustration the lower sash is much larger than the upper, and consists really of two casements hung to stiles to which the weights are attached, and which slide up and down in the ordinary grooves. The upper sash is simply an ordinary sliding sash; this can, however, be fitted with folding casements if desired. The fittings required for a combined window of this kind are somewhat numerous. Besides the usual pulleys, lines, and weights, there ought to be a bolt at the foot of each casement and a sash-fastener at the top; sunk handles for raising the lower sash may with advantage be fixed in the bottom rail, and a loop in the top rail of the upper sash for lowering this by means of a stick and hook. A short but strong bolt to unite the meeting-stiles of the casements allows the two casements to be raised together, but the same object may be attained by carrying a rail across the head of the casements. The latter method, however, is somewhat clumsy, the window becoming practically an ordinary sash-window with casements hung in the Casement-windows are almost universal on the Continent Indeed, large casement-windows reaching to the floor are commonly known as " French windows". They are, however, now frequently used in this country, being better adapted than sash-windows for the small mul-lioned windows now in vogue. They consist of a casement hung (generally with butt hinges) in a fixed solid frame. The casement may open inward, which has the merit of allowing the glass to be easily cleaned on both sides, but adds to the risk of rain being driven into the room and of the window being blown open, and interferes with the blinds and curtains; or it may open outward, when these conditions will be reversed. Fig. 91 shows the jamb and sill of an inward-opening wood casement, and Fig. 92 those of one opening outward. The sills should be of oak, weathered and throated, and provided with a weather-tongue. "French casements" are usually hung folding, and the meeting-stiles may be shaped in a great many ways; a good watertight arrangement is given in Fig. 93, and another was given in Plate V. Fig. 94 contains details (one-fourth full size) of the N.A.P. wood casement, which is so designed that it will open either inward or outward on a double-knuckle hinge shown at c. Special precautions are taken to prevent the ingress of rain; these are clearly explained by the drawings. The purpose of the invention is to facilitate the cleansing of the glass, while at the same time retaining some of the advantages of the outward-opening casement.