The ordinary method of framing around openings, by mortise and tenon joint, was shown in Fig. 30. This method answers very well where the floors are not apt to be heavily loaded or the openings very large. In first-class dwellings, however, and all larger buildings, the author recommends that all headers over 4 feet long be supported at the ends by iron hangers or stirrups instead of by mortising. In heavy construction the saving in the extra amount of lumber required by the old method will offset the cost of the hanger. The full strength of the header, at the end, is obtained, and in case of fire such a joint would stand much longer than the mortise and tenon joint.

Most building laws also require that headers over 4 feet long, in all buildings except dwellings, shall be hung in hangers or stirrups.

For dwellings and light construction the author recommends the use of the Goetz and Duplex Hangers, shown in Fig. 44.

57 Framing Of Headers And Trimmers 20030

Fig. 44.

These hangers are made in a great variety of sizes to suit any size of timber, and are now carried in stock in most of the larger cities. They are supported by inserting the lugs into holes bored near the centre of the trimmer, and thus possess the advantage over stirrup hangers that they are affected by only about one-half the shrinkage in the trimmer, while the ordinary stirrup iron is supported at the top of the timber, and consequently the bottom of the stirrup must settle, and the header with it, by the amount of the shrinkage in the trimmer. Unless the trimmer is well seasoned this dropping of the header, due to the shrinkage of the trimmer, will be sufficient to crack and distort plastered ceilings. Even where the joist hangers are used pains should be taken to secure well-seasoned timber.

With the Goetz Hangers the beam supported is tied to the hanger by a spike, driven through a hole in the bottom of the hanger into the beam; for large timbers lag screws may be used. The Duplex Hanger of the smaller sizes holds the joist by means of lugs on the sides, as shown in the cut at A; the larger hangers have a bolt which passes sideways through the end of the joist, as at B. The Duplex Hanger may also be bolted to the trimmer, as shown in Fig. 45, thus absolutely preventing any possibility of the trimmers spreading. If the headers are very long the tail beams also should be hung in hangers, as shown in Fig. 46. Where the headers are short the tail beams are generally mortised into the header in the usual way.