Fig. 60. - -Fitting a Skirting Board; Method 2.

In making attic and cellar stairs, and stairs in cheap buildings, a wide skirting board is sometimes nailed to the studding, and the treads and risers butted against it, supported by furring strips nailed to the skirting board. This method should be used only upon the most common work, since the joints are certain to open as the building seasons.

In building closed string, buttress, or curb stairs, the construction of which is illustrated in Fig. 62, the treads and risers are frequently housed into the wall string, or wall skirting board, as at a, and into the inside of the buttress, or face string, as at b, by the same method, and firmly wedged and nailed. The rest of the closed or buttress string is then built upon the inside piece, as at c. In constructing buttress stairs, the flight sometimes is built clear of any wall or other support, in which case the buttresses should be made of sufficient strength to support the flight and the heaviest load they ever will be required to carry. If stringers are used, they should be far enough from the skirting board (6) to allow wedges to be driven which will force the treads and risers into their places, as illustrated in Fig. 61. If it is desired to build an economical flight of stairs of this type, a plank, face stringer may be used, housed the same as the wall stringer, as indicated at n, Fig. 76.

Fig. 61. - Fitting a Skirting Board Method 3.

Fig. 62. - Construction of Buttress Stairs; Method 1.

Another method is shown in Fig. 63, in which the skirting board (a) of the face string is housed into the treads and risers; this is the stronger way, as the joints are less liable to open than if built by the other method, since the framework which supports the buttress, rail, and face casing is fastened to the treads and risers. There are other methods of constructing a buttress string, but the two above indicate those ordinarily used.

Fig. 63. - Construction of Buttress Stairs; Method 2.

In places where lumber of the proper dimensions cannot be secured, a stringer is sometimes built by a method similar to one of those illustrated in Fig. 64. A built stringer, however, is rarely satisfactory for any but very light flights.

Figure 65 shows two methods of fastening the heads, or tops of stringers, either of which is satisfactory, and may be used where the stairs are not supported by section posts.

49. Forms of stairs. - There are different forms of stairs which may be adapted to various shapes of stair openings.

Fig. 64. - Methods of Building Stringers.

The straight run (Fig. 54) has no turn, being straight from top to bottom, and is an inexpensive form of stairs to build. It is preferred upon common work for that reason, although a flight of this sort cannot be made so attractive as if it had an angle with a platform. It is less ornamental, and is used less than any other form, though in buildings where large crowds are to be accommodated the architect tries to secure a straight flight if possible.

Fig. 65. - Methods of Fastening the Tops of Stringers.

A platform flight (Fig. 55) is a popular form, as it makes a safe and easy ascent. It may be made as ornamental as desired, and is frequently the center of the decorative scheme of an elaborate hallway. The figure shows a platform, illustrating all the turns of a full platform flight.

A winding flight usually is avoided as much as possible, as the narrow treads close to the post or rail cause many accidents, besides appearing small and pinched, as compared with the broad turns of a platform flight. A winding flight rarely should have more than four risers in the winding posts, though in attic or cellar stairs this is not observed, unless there is plenty of room. The upper half of Fig. 68 shows the plan; a full winding flight would make all of its turns by winders.

A dog-leg flight (Fig. 66) sometimes is used where it is necessary to economize in room and as wide a flight of stairs as possible is desired. The face string of the lower flight is directly under that of the upper flight, making an awkward place to receive the rail and balusters of the lower flight, since either they must stop under the face string of the upper flight, or there must be an easement to allow the hand to pass by, as at a. This makes the lower flight narrower. The rail therefore is frequently omitted between the place where the rail easement occurs and the post.

A box flight is built between two walls, and is the cheapest form of stairs to build, as there is no finish upon the outside, a skirting board being fitted against the steps at each side by one of the methods previously described, and a rail fastened to either one or both of the walls.

The method commonly used in framing the face string of stairs into the posts is shown in Fig. 67, where a finished face string (a) is used. A tenon is cut upon the end of the string to fit the mortise in the post, as shown at b. If the angle is turned by a platform, the risers (c, c') are also mortised into the section posts, as shown at d, d, the top of the upper riser (c') being the height of one step above the top of c. If the angle is being turned by winders, the risers, c and c', are the lower and upper risers entering the section post.