Toothing of the masonry is not permitted in many architectural specifications. Why does toothing provide less strength than raking or stepping back the masonry wall?

Toothing is not as strong because of the difficulty involved in properly filling and compacting the mortar for the full depth of the head and bed joints. Much of the mortar at the tooth portion of the wall must be installed by pointing the joints, and it is difficult to point the mortar in the back portion of the joints. As a result, these tooth joints are often poorly filled, and as a result, create a weak plane within the wall that is susceptible to cracking.

Toothing, however, is sometimes necessary when connecting to an existing wall. If the joint cannot be stepped back, providing a vertical expansion joint at such interfaces may be an alternative to toothing.

When toothing must be done, extreme care must be taken to carefully point these joints to ensure that they are completely packed with mortar for the full depth.