Laths. (A.) Laths are made of poplar, pine, spruce, oak, or almost any wood which may be desired, though the harder woods are less desirable, for if not thoroughly seasoned before laying, they may twist and either break the clinch or crack the mortar. Laths are usually made at the sawmills of the waste and edgings, and are of two widths, 1" and 1 ½". The former gives a better clinch to the mortar, while the latter makes the spaces between the studs stiffer; thus the conditions are about even as far as holding the mortar is concerned, but the wider laths may be laid faster, and require fewer nails.

(B.) To minimize the danger of cracks in an inside corner, it should be tied together by breaking the joints of the laths by some method similar to that indicated in Fig. 130, pieces of 2"x4" (e) being nailed on after the laths are in place. On account of the length of time this takes, it is done only upon the best class of work. Ordinarily, the laths are laid the entire height of one wall, and nailed upon the stud, f, as shown by the dotted lines at c, and the furring piece, d, nailed upon them to furnish a nailing for the laths of the other wall. Joints should not be made in the laths upon the stud above either side of a door frame, as the swinging and slamming of the door will in time break the plastering at these joints.

Fig. 130. - Lathing an Inside Corner.

Laths should not be laid more than 5/16 " apart, with one 3d fine nail to each bearing.

The joints of the laths of a plain wall should be broken every 12 or 15 laths, as in Fig. 131. When the laths are laid directly upon a wide timber, their edges should be cut under, as shown in Fig. 132, to allow the mortar to clinch.

Fig. 131. - Lathing a Straight Wall.

Fig. 132. - Lathing on a Wide Timber.

(C.) An outside brick wall less than 16" in thickness should have furring strips laid upon it, upon which laths should be laid. This allows an air space, which insures against moisture destroying the surface of the plaster, or causing the paper to peel off. (See D, Topic 14.)

Studs for lathing should be 12", 16", or 24" between centers, as the common length of laths is 48". (See Topic 24.) Upon most work 16" is the usual distance, but 12" is sometimes used upon heavy buildings; 24" is often the distance between centers of rafters, as sufficient strength is thereby secured, and unnecessary weight and expense is avoided; 16" and 20" spacing is common.

(D.) There are several forms of patent laths, some of wood made in the form of matched boards, which add much to the strength and warmth of the building. Others are of metal, and are used chiefly upon fireproof work, and for fitting around circular walls and awkward places.

In localities where considerable building is in progress, there are men who do nothing but lathing, and who are exceedingly expert at it. As these men usually are paid by the thousand it is the carpenter's place to prepare the nailings.