Carpentry - Griffith

It is the author's hope that the following text may be of service to apprentices to the trade, to vocational and trade school students, and to manual training students. The author's experience as a carpenter leads him to feel that not a few journeyman carpenters may find their horizon widened and their usefulness as framers of the unusual roof increased by a study of Chapter IV where an effort has been made to indicate how the principles involved in framing the square and octagonal roof may be "generalized" so as to make possible their application to roofs of any number of sides. Beyond this, the book makes claims to being nothing more than an elementary treatise of the essentials of carpentry.

No apology is offered for making use of trigonometric solutions of plane right triangles as a basis for developing generalized roof framing principles in Chapter IV. There is absolutely nothing in the use of natural trigonometric functions to prevent their introduction early in the mathematical experience of a boy, except academic tradition. The author has made use of this mathematical tool with upper grammar grade boys with less effort upon their part in mastering the principles than was expended in mastering square root. The ease with which roof framing problems lend themselves to solution by the use of natural trigonometric functions and the readiness with which problems may be generalized thereby has emboldened the author to make use of it in a text as elementary as this. No previous knowledge of trigonometry is presupposed, the Appendix provides all the information required for the solution of any problem given herein.

Should a reader, because of lack of time or for any other cause, not care to consider more than roof framing of the square cornered building, he will find a complete treatise in Chapter III without reference to solutions other than by common arithmetic. Appendix IV offers a still more abbreviated approach to both square and octagonal roof framing.
The greatest good in studying the chapter on “Estimating” will come only when each student is provided with a set of plans and specifications completely drawn, as by a practicing architect. Plans and specifications, such as will serve the purpose, can be purchased at small cost from architectural companies, should local architects be unwilling to provide sets for the schools.

Also, there must be provided for each student, catalogs of lumber and millwork specifications and prices. These can be obtained from mail order lumber and millwork companies. As a rule, local lumber and millwork companies are glad to provide such data, but it must be in a form complete, and readily accessible to be of the greatest value.

49. Sheathing or Sheeting. After the frame work of a building is erected and the openings made in the frame for windows and doors, the sheeting is to be placed. Sheeting is placed either horizontally across the studs or diagonally, sometimes both ways, depending upon the specifications of the architect. The diagonal is somewhat stronger but is more expensive. The horizontal is satisfactory upon ordinary frame dwellings, especially where the building is braced at the corners by studs cut in diagonally, or by sheeting placed diagonally at the corners as in Fig. 90. Such
sheeting should be matched and well nailed with two 8d nails to each stud. Building paper should be placed upon the sheeting to further protect the interior from cold.

Roof sheeting for shingle roofs may best be of unmatched boards spaced about 2" apart. For slate, matched stock should be used and this covered with a tar or asphalt paper.

In making the face cut on roof boards for hips or valleys the framing tool or the T-bevel may be made use of, being set to the complement of the angle used in making the side or cheek cut on jack rafters. The complement angle in this case equals 90 less the angle of the side cut of jack. Or, if the framing square is to be used, the same numbers used in making the side cut of the jack will be used in laying out the face cut of roof boards, with the scribing being done along the tongue instead of along the blade as in the case of the side cut.

A second T-bevel may be set as in Fig. 91, the beam being placed across the edge of the jack and at right angles to it, with the blade adjusted to the cheek or sawed surface of the jack which is to fit against hip or valley rafter. A framing tool might be used.

Carpenters more frequently, however, get the angles for sawing roof boards by laying the board to be cut out over the hip or valley rafter, then sawing along the side the rafter as in Fig. 92. In warm climates, weather boarding is often applied directly to the studs, no sheeting being used; the frame being strongly braced at the corners.

50. Scaffolding. Cornice is placed after sheeting. To do this advantageously it is necessary to erect scaffolding or staging. Fig. 93 illustrates a common type. Stock 2"x4" is used for the uprights, and I"x6" for the horizontal members and braces or stays. Planks are placed upon these horizontals as shown. Fig. 94 illustrates a substitute for staging, a scaffold bracket upon which planks are laid.

51. Cornice. Cornices are generally classified as open or skeleton, and box, Figs. 95 and 96. Each of these types will be found constructed in almost endless variety of forms. The illustrations shown will serve the purposes of this text. The student should familiarize himself with the various common forms, details of which may be got from any good, modern book on building details.

In making the various cuts on cornice work, a miter-box must be available for mouldings. The old type of wood miter box, with the various necessary cuts laid out in its sides is satisfactory. Some experimenting will be necessary upon the part of the beginner to determine the manner of placing the moulding in the box to give the correct cut.

The cuts for the plancher, which rests in the planes of a hipped roof and which must be membered around a corner are determined in a manner similar to that described for roof boards, Sec. 49, from the cuts of the jack rafter cheeks.

Fig. 97 illustrates the manner of "framing in" the lookouts on gables where a skeleton cornice is used. Also there is illustrated the manner of placing lookouts in gables for a box cornice. Unless the cornice is quite wide, these blocks are merely fastened to the underside of the roof boards at intervals of 3 or 4 feet. The depth of these blocks will depend upon the manner of framing the tail ends of the rafters.

52. Raked Mouldings. In all cases where a moulding resting in one plane, as crown or bed moulding at the eaves, is to be membered with moulding swung up out of that plane, as up a gable, one of two things must be done to make the surfaces of the mouldings match or member properly at the joint: (1) The moulding at the eave may have its top edge tipped forward until its top edge lies in the same plane as the top edge of the corresponding gable moulding; (2) a moulding with a new face may be worked which will member with the eaves moulding when their reverse surfaces are fitted to the fascia or, in case of bed moulding, to the frieze.

To member by means of the second method proceed as follows: (1) Make a full sized drawing of a cross-section of the moulding, Fig. 98. (2) Draw a number of lines thru the more important refer- ence points of the moulding at an angle equal to the pitch of the gable. (3) Draw horizontal lines thru the points of reference and erect a perpendicular thru these passing thru the back of the mould as A-B. (4) Lay off a line C-D, Fig. 98, perpendicular to the oblique lines. (5) Using the lines A-B and C-D as reference lines, transfer the distances of the various points on the eaves moulding, measured horizontally from A-B, to pitch lines measured obliquely. A curve traced thru these points will give the shape of the moulding required for the gable. Since this moulding would, in all probability, have to be worked up especially for any particular job, this practice is not followed except upon large or important work. Cornices are usually designed so as to avoid such work.