This series consists of five volumes, four of which are intended as textbooks for pupils in manual-training, industrial, trade, technical, or normal schools. The fifth book of the series, the "Hand-book in Woodwork and Carpentry," is for the use of teachers and of normal students who expect to teach the subjects treated in the other four volumes.

Of the pupils' volumes, the first two, "Elements of Woodwork " and "Elements of Construction," are adapted to the needs of students in manual-training schools, or in any institution in which elementary woodwork is taught, whether as purely educational handwork, or as preparatory to a high, or trade, school course in carpentry or vocational training.

The volumes "Constructive Carpentry" and "Inside Finishing" are planned with special reference to the students of technical, industrial, or trade schools, who have passed through the work of the first two volumes, or their equivalent. The subjects treated are those which will be of greatest value to both the prospective and the finished workman.

For the many teachers who are obliged to follow a required course, but who are allowed to introduce supplementary or optional models under certain conditions, and for others who have more liberty and are able to make such changes as they see fit, this series will be found perfectly adaptable, regardless of the grades taught. To accomplish this, the material has been arranged by topics, which may be used by the teacher irrespective of the sequence, as each topic has to the greatest extent possible been treated independently.

CHARLES A. KING.


PREFACE TO CONSTRUCTIVE CARPENTRY

BEFORE undertaking the work included in the following pages, the student should have passed through that contained in "Elements of Woodwork " and "Elements of Construction," or their equivalent. In preparing the material for this book, it has been the author's first purpose to arrange and present the subjects in such a manner that they will be easily adaptable to use in technical schools for students of architecture and engineering, and in trade and industrial schools for the teaching of the principles and methods of building construction, to students who plan to make carpentry a means of livelihood.

The matter as arranged has special reference to the laying out and planning of the construction of wooden buildings, for the foreman as well as for the one who is to work under his direction. The important problems met with in preparing a house for the inside finish are discussed, and the relation between the carpenter and other mechanics is explained.

The teacher should see that there is a select library for the use of the students, including the leading trade periodicals, from which should be selected subjects for discussion, research, and essays bearing upon the different stages of the work.

The method of teaching the use of the steel square was devised by the author to meet classroom conditions; the formulas and instruction given may be applied to any pitch or plate angle or to any combination of them.

17. The full frame. Fig. 19 illustrates the joint forming the basis of construction of the heavier members of a full frame house (Fig. 20) in which every joint is a mortise and tenon joint, a pin being driven through the hole (c, d of Fig. 19), drawing the tenoned timber to its place. Floor joists, studs, tail beams, headers, etc., are mortised and tenoned; in fact, the best work of this form of construction is done without the use of nails, except for rafters and in spiking floor joists and small pieces to their places.

This is the old-fashioned way of framing, and until about 1850 was the method commonly used. A frame of this sort is rarely built now, as the heaviest buildings are of steel, or of the form known as the mill, or slow-burning, construction.

18. The half frame. - The combination, or half frame, a combination of the full and balloon frames, is quite generally used in the best class of dwellings, and other light frame buildings. It follows the full frame as the posts, girts, and often the braces are concerned, though the last are frequently of the balloon type, and only spiked. In the best frames of this type, the studs are mortised and tenoned at the top, and nailed at the bottom, though ordinarily they are nailed at both ends.

19. The balloon frame. - - The balloon frame (Fig. 21) is built by spiking or nailing all timbers together, and is the cheapest form of construction for a frame house. The studs are usually continuous from the sill to the plate, on the sides of the house, except at the openings, and in the gables to the rafters, if pieces of the right length can be secured, otherwise they are usually pieced by means of a fished joint.

The ribband, or ledger board (a), is cut into them to support the floor joists of the second floor.

A balloon frame is a fire trap unless bridged by pieces of scantling (6), which are put between the studs to prevent the circulation of air, thereby reducing the danger from fire. Bridging also makes it difficult for vermin to pass from one story to another, and adds much to the warmth and stiffness of the house. It is a good plan to fill in between the floor joists upon the sills with a brick nogging (f), which assists the fire and vermin-resisting qualities of the building. In the full and combination frames this protection is formed by the solid girts.

A well-built balloon frame is satisfactory for a moderate- sized house, but since it invites poor work and a certain class of builders cannot resist such a temptation, this form of construction has a worse reputation than it deserves. In many cities a balloon frame is not accepted within the fire limits, though a half frame usually will be accepted wherever a wooden building is allowed.

20. Sills. In framing the sills of a house the corner joints usually are made by being halved together as at a, Fig. 22. The sills of a heavy building are frequently fitted together by an open mortised joint, as at 6, Fig. 22. If the sills are built up and spiked together, they should be crossed at the corners as at c, Fig. 22. Large straight timbers are difficult to obtain in long lengths, and are therefore often built up of others of smaller dimensions. Timbers built up in this way have about 75 per cent of the strength of solid timbers of the same size. If the pieces are sprung, or crooked, they often may be straightened by nailing pieces together which are sprung in opposite directions, one piece straightening the other. In a cheap building, the sills sometimes are fitted against each other with a square butt joint, depending upon the boarding and the finish to hold them together. This is bad construction, and never should be used by a carpenter who values his reputation.

The girders, which extend across the house to support the floor joists and the partitions, are made uniform in size with the sills, and the floor joists are cut to fit them by the same method as at the sills.

21. Corner posts. The corner posts of a full or of a half frame house are framed at the girts by a mortise and tenon joint, the tops of the raised girts being flush with the floor joists, as at w, Fig. 20; and, in order to prevent cutting away the post too much at one place, and to allow a longer tenon upon each girt, the sunk or dropped girts are placed low enough to allow the floor joists to rest upon their tops, as shown at z, in Fig. 20.

The girts sometimes are cut into the corner post with a beveled shoulder, as shown in Fig. 23, to prevent the entire weight of the girt from resting upon the tenon, though this is not usually done upon ordinary work.

In a full or a half frame house, the timbers are often weakened by the mortises cut in them, unless stirrup irons are used to support the joists, which would otherwise be tenoned into headers or girts. Other timbers which are usually supported by mortise and tenon joints may be supported in the same way, though a mortise cut in the middle of the depth of a timber affects it less than if cut upon one edge or corner.

The joints between the corner posts and sills of all frame buildings usually are made as shown in Fig. 24, though frequently they are spiked in the cheaper balloon frames. Corner posts may be built by one of the methods shown in Fig. 25.

22. Braces. In making the cuts, and finding the lengths of braces shown in Figs. 20 and 21, the steel square is used. All measurements generally are worked out upon the scale of 1" to 1'. The square most conveniently marked for the use of the framer is divided on the outside into twelfths of an inch. This division may be used easily in working to an inch scale, each inch being read as one foot. In using the steel or framing square, the tongue or short side should be held in the left hand, and the blade or long side in the right, thereby bringing the square into the position shown in Fig. 27.

23. Floor joists. - The methods of resting the floor joists upon the sills and girders are shown in Fig. 29: a is the method frequently used upon cheap buildings; b, upon the best class of buildings; and c illustrates a method sometimes used where it is necessary to avoid the height above the sill at a, and where it is not desirable to take the time to cut mortises. The joists need be no longer than to reach the stud, as at d, though if they extend to the outside of the stud, they may be spiked to the side of each stud they come against, thus giving additional strength.

As there is so much difference in the size of timbers, it is necessary, in order to make the floor joists line up straight on top, always to size the floor joists to 1" narrower than the timber, as shown in Fig. 29. This sizing should be done from the top edge of the joist, which in every case should be the crowning or rounding edge, so that when the floor is loaded, the deflection will tend to straighten the joists.

A floor joist should be nailed against the outside wall, to give a nailing for the floor boards and the ceiling laths.

Two floor joists, with a 2" space between them, should be placed under the partitions, or a double floor joist may be used instead, if a piece of 1" X 3" is nailed to each side of it, to give a nailing for the flooring and the ceiling laths.

Floor joists in almost every case should be placed 16" to centers. As laths are cut 48" long, this distance gives four nailings to each lath and makes cutting unnecessary. If the space to be filled is not a multiple of 16", the variation should all come at one side of the room, so that the laths will not have to be cut more than necessary. In heavy work the floor joists are often placed 12" to centers. If floor beams are used as trimmers, to carry the header of a flight of stairs, they should be doubled, unless otherwise supported. Headers and trimmers carrying but one or two tail beams will do if a single thickness is used.

If a floor joist is sprung sideways, it must be held straight by "battens" or bridging until the flooring is nailed, or there will be enough deflection when the weight is placed upon it to crack the plastering of the ceiling below.