Balconies and Galleries. In churches and lecture halls it is almost always customary to have one or more balconies or galleries, extending sometimes around three sides of the main auditorium, but more often in the rear of the room only. These galleries are supported by the wall at the back and by posts or columns in front, and the framing for them is usually a simple matter.
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 in front, and various other considerations. Usually posts 2X 10 or 3X 12, and girders SX 10 or 10X 12 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.
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 1-1 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 extend ing the joists beyond the girder, as is shown in Fig. 233. A strip of board E, about 11 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 II of the same size on top.
If the overhang of a gallery is more than 5 feet it must usually he 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 canti levers 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 bal cony 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.