This section is from the book "Cyclopedia Of Architecture, Carpentry, And Building", by James C. et al. Also available from Amazon: Cyclopedia Of Architecture, Carpentry And Building.
Fig. 233 shows a sectional view of a gallery frame, as they are commonly constructed. There is a girder A in front, which rests on top of the columns T, and supports the lower ends of the joists B, forming the gallery floor. The size of these pieces will depend upon the dimensions of the gallery, the spacing of the columns which support the girders in front, and various other considerations. Usually posts 2 X 10 or 3X12, and girders 8 X10 or 10X12 will be found to be sufficiently strong. The joists should be spaced from 14 to 20. inches, center to center. Very often cast-iron columns are employed to support the girders. At the top, where the joists rest on the wall, they should be cut, as shown in the figure, so that they may have a horizontal bearing on the masonry, and at least every second joist must be securely anchored to the wall, as is the one shown. Usually galleries are made with straight fronts, but if it is desired that the seats should be arranged in concentric rings, all facing the speaker, the joists may be placed so as to radiate from the center from which the seats are to be laid out.
Fig. 233. Sectional View of Gallery Framing.
The seats are arranged in steps, one above the other, and the framing for the steps must be built up on top of the joists, as shown in the figure. Horizontal pieces C, usually 2X4 or 3X4 in size, are nailed to the joists at one end, and at the other end they are supported by upright pieces D. The uprights are either 2X4 pieces resting on top of the joists, or strips of board, 1 inch to l 1/2 inches thick, which are nailed to the sides of the joists and to the sides of the horizontal pieces. Both methods are shown in the figure. If boards are used, they should be placed on both sides of the joists. Great care should be taken to see that the horizontal pieces are truly horizontal.
Balconies and galleries almost always project a considerable distance beyond the line of columns which support the lower ends of the joists. This projection varies from 3 feet to 10 or 12 feet. If the overhang is not more than 5 feet, it can be supported by extending the joists beyond the girder, as is shown in Fig. 233. A strip of board E, about 1 1/2 inches thick, is nailed to the side of the joist, and a furring piece F is nailed on top of the joist at its lower end to make it horizontal. The railing at the front of the gallery should be about 2 feet high, and may be framed with 2X4 posts G having a cap H of the same size on top.
Fig. 234. Section of Gallery Framing with Overhanging Portion.
If the overhang of a gallery is more than 5 feet it must usually be supported by a brace, as shown in Fig. 234. The brace A may be nailed to the post B and to the overhanging joist C, or framed into these pieces. If the construction is very light, the braces may consist of strips of board nailed to the sides of the joists, but in heavy work they must be timbers of a good size, well framed into both the post and the joists. The braces can only be placed at points where there are posts, and to support the ends of the joists which come between the posts there must be a girder D, running along the front of the gallery and supported by the braced cantilevers at the points where posts are placed.
The forms of balconies described above are all of such a sort as to require the presence of posts in the main floor below the balcony to support it, but it very often happens that such posts are very undesirable and must be avoided if it is possible to do so. In this case the balcony must be supported from above in some way, and the method most commonly employed is to hang the outer end of the main timbers from the ceiling of the main hall or room of which the balcony forms a part. Hangers made of round or square iron or steel rods are used, and these are fastened at the upper end to some member of the floor construction of the floor above, or to some member of the roof construction in case there is no floor above. The most common arrangement is to fasten the upper end of the hanger to the lower chord of the roof truss.
Fig. 235. Details of Balcony Construction Showing Hanger Attached to Roof.
Fig. 235 shows a balcony constructed as described above. One side is supported by the masonry wall of the building, marked F in the figure, and the other side is hung from the roof or ceiling by means of the hangers marked E. At L is shown a section through the balcony from the wall to the inside edge, while at M is shown a view looking at the edge of the balcony from the inside of the hall or room in which the balcony is situated. The principal supporting members of the construction are the pieces marked A which run well into the wall so as to obtain a sufficient support at this end.
These pieces are made double or in pairs, as shown in the end view M, and are separated a little so as to allow the hanger rod to pass between the two pieces as shown. E is the hanger, which is a round or a square rod about 1 inch in diameter. The pieces A should continue a short distance beyond the point where the rod passes between them, and the ends may be cut to any shape desired in order to give them a pleasing appearance, as shown. They should be spaced 7 or 8 feet apart and on top of them may be placed ordinary joists of small size, marked B in the figure, which are spaced about 12 or 14 inches apart. On top of the joists B is laid a rough floor, marked C in the figure, and above this again is laid the finished flooring of the balcony D. A joist should be placed on each side of the hanger E, as shown at N and 0, and against the joist marked 0 should be nailed the finished fascia piece G. This finished piece G should run up past the under boarding C and stop against the under side of the finished top flooring of the balcony. There should be a bed molding H at the juncture between the piece G and the top flooring D, so as to cover and conceal the joint.
The hanger E should pass between the pieces A, and should be threaded at the bottom so as to receive a nut J by which it may be tightened up. There should be a washer I consisting of a square plate of iron, between the nut J and the wood of the pieces A, so the wood will not be crushed and so that the nut will not sink into the wood.
The under side of the balcony seen from the floor of the main hall may be treated in any one of a variety of ways. The joists may be furred and lathed and plastered on the under side so that a plastered surface will be presented, or the under side of the joists may be covered with sheathing, V-jointed or beaded, or the joists may be more carefully chosen and left exposed to view from below.