Lath provides a means of holding plaster in place. Typically, three types of lath can be found throughout North America: wood lath, metal lath, and rock lath. Lath Wood lath came into common use 400 years ago, and was still seen regularly until about 70 years ago. Today, wooden lath is most commonly encountered in the New England area, and it is made of wood strips approximately 2 inches wide x 4 feet long. The strips used in historic structures had slightly undulating surfaces, as they were skillfully hand split from blocks of pine or hemlock. Because of these irregular surfaces, the hand split lath produced the best form of wooden lath. It afforded the plaster mixture many areas to “squeeze into”, so that it could harden and become “keys”. The keys are the mechanical locks which secure the plaster mortar to the wood. Introduction of the circular saw made possible the production of sawn lath strips in the 1800s. Cut from rough lumber, they are similar in size to spli...