No. 20. A notched joint is made by cutting out a portion of one timber. It is used where it is desired to reduce the height occupied by the upper timber. Joists are notched on to wall plates.
Fig. 265-20 Notched
No. 21. A checked joint or double notch is made by cutting out notches from both the timbers so as to engage each other. It is used where a single notch would weaken one member too much.
Fig. 265-21 Checked
No. 22. A cogged or corked or caulked joint is made by cutting out only parts of the notch on the lower piece, leaving a "cog" uncut. From the upper piece a notch is cut only wide enough to receive the cog. A cogged joint is stronger than a notched because the upper beam is not weakened at its point of support. It is used in heavy framing.
