Joints Used In The Construction Of Floors. In fig. 334 is illustrated a simple method of joining tie beam a a to the wall plate b; a notch, as c, being cut in the lower edge of tie beam to admit of the wall plate passing into it. This joint is improved by adding a "key," as d, in fig. 335, shown in plan at e e; f shows the notch cut in lower edge of tie beam c c, into which the upper part of "key," or "cog," d fits; a a is the wall, b b the wall-plate. In fig. 336 we illustrate a method of joining a " pole plate" b to the tie beam a a, by a, notch c cut in the upper edge of tie beam d. In fig. 337 another method is illustrated in which a "key" or "cog" a is used. Fig. 338 illustrates a method of joining the joists a a of floor to the wall plate b b; a chase c c is cut out in face of wall plate, but with a rib or key d left in its centre; this rib passes into the part e", cut out of the edge of the joist a a, being plan of same; another method is illustrated at e", this part being cut out of lower edge of joist, which is made to embrace the wall plate b b, this remaining uncut. In fig. 339 are illustrated, at a b c, three other different ways of joining joists to wall plates, or when one timber crosses another at right angles; the dotted lines show the joists; in c, a wedge d is used to tighten up the joist. Fig. 340 illustrates an arrangement in which the tie beam a a is secured to a cross beam b, c being the plan of under edge of a a. The joining the foot of a rafter with the tie beam is done in a variety of ways; two ways, at a and b, fig. 341, are shown. The simplest method of effecting the junction is shown at c, same figure; but this is very weak, the whole strength of the joist depending upon the nail which secures it to the beam.

Fig. 336.

Fig. 337.

Fig. 339.

Fig. 340.

Fig. 341.

Fig. 342.

By cutting slots on the face of the beam of the same shape as the feet a b of the rafters, the joint is rendered much stronger. In fig. 342 another method is illustrated, in this a tenon d is cut on the sloping face of the foot of rafter a a, which goes into the mortice e e in face of tie beam b b. In all these joints with sloping faces the butting end, as c, should be at right angles to the upper line of face of rafter a a. Fig. 343 illustrates two methods of joining the foot of a king post with the tie beam ; at a a tenon is cut on foot of rafter which goes into the mortice b cut in upper side of tie beam; in the lower diagram the tenon is shown by the dotted lines, and a wedge c is used. In fig. 344 a more complicated method is shown, in which an iron strap is used to unite the foot of the king post a a with the tie beam b b, the foot of the king post is tenoned at c into the tie beam; d d the strap, e e the iron "gibs,"f f the " keys," for driving all up tight. The feet of the common rafters are joined to the pole plate, as in fig. 345, at a b, where no pole plate is used, the wall plate is placed near the outside line of wall, and the common rafters joined to it, as at c, fig. 345. The junction of feet of struts or braces with the foot of king post is illustrated in fig. 343, the simplest method being shown at d, the end butting against the sloping shoulders of king .post.

Fig. 343.

Fig. 344.

A better and stronger method is shown at e, a tenon being cut at end of strut, passing into a mortice f cut in shoulder of king post. The junction of upper end of strut with head of king post is illustrated in fig. 346, in two methods - one on each side of the centre line a b', at b c a simple tenon d is made, the face b c being of the same width as that of the strut i, to shorten this face the joint e f g is sometimes used, an angular tenon f being given to the strut j. The ridge pole is inserted in the grove h. The strut or brace corresponding to g g, in fig. 344, may be joined to the under side of rafter a a, fig. 347, by one or other of the two methods shown; as by a simple tenon at 6, or by an angular tenon at c c. In fig. 348 we show the method of joining head of " straining beam" a of a queen-post roof with "head" of "queen post" b, c being the end of the principal rafter.

Fig. 345.

Fig. 346.

Fig. 347.

Fig. 348.

Fig. 349.

Another method is shown at d e, the queen post f f being made in two pieces, as at g g, the "straining-cill" and strut e being placed between these pieces, as at h, and the whole being secured together by bolts and nuts as shown. In same figure, i shows the foot of queen post connected with tie beamj, and the end of " straining-cill" k and strut joined in same way to the queen post i, made of two pieces as at g g. In the same figure n shows a "purlin" and a method of joining it to the "principal rafter" o; the purlin h butting up against the piece n fitting into a groove made in the upper face of the principal rafter o, m common rafter. In fig. 3, Plate XXXIX., is illustrated the usual method of joining the collar beam a with the rafter b, a part being cut out at c; if the faces of the collar beam and rafters are required to be made flush, the junction is made with a "half-lap" joint, half of the part of collar beam being cut away and half of the rafter being sunk with a groove or mortice of the shape of c; d shows the junction of foot of rafter with wall plate, with what is called a "bird's-mouth" joint. In figs. 349 to 351 we illustrate the methods of joining the feet of cross rafter with wall plate. Fig. 349 is that employed for small roofs; a b are the "wall plates" joining at the corner j', the two are joined by an angular piece h h, which is called an "angle tie," which receives the foot of the " hip rafter;" but in roofs of greater span, a piece i i called the " dragon tie,"

Fig. 350.

or "dragon beam," is added, and this carries the foot of the "hip rafter," which is tenoned into the mortice made in the "dragon tie," as shown. The "dragon tie" b, fig. 350, is tenoned into the "angle tie" h h, fig. 349, by a "tusk tenon" c, the other end of the dragon tie at the corner e, fig. 349, is half lapped to the wall plates, as shown at d, fig. 350.