Fig. 166. Joists notched on to Wall Plate.
Joists are sometimes thus fitted to wall plates, and when the joists differ in depth the depth of the notches is also varied so as to bring the upper surfaces of the joists to the same level. It will be seen there is nothing to tie the wall plate in toward the direction of the arrow.
In other cases the end of the joist projects, and is left on as shown in Fig. 167; it then grasps the wall plate and holds it in.
If the notch is required to be a deep one, half of it may be taken out of each timber, as shown in Fig. 168.
Fig. 167. Joists notched out to Wall Plates, ends left on full depth.
Fig. 168. Double Notching.
When each timber is notched to half its own depth, this joint becomes another form of halving (see page 64).
This is a good way of joining wall plates at angles. The inside of the joint is dovetailed, and the outer side is left straight.
Sometimes the joint is tightened up by a wedge driven in on the straight side.
The defect of the dovetail is partly remedied by the grasp the projection of the upper beam has upon the lower.
Fig. 169. Dovetail Notch.
Fig. 170. Tredgold's Notch.
The form of joint shown in Fig. 170 was recommended by Tredgold as a substitute for the dovetail, but is seldom, if ever, used in practice.
A similar form was recommended by the same authority for uniting the ends of a collar tie to the rafters (see page 75).