Besides the usual cross-furring there is generally more or less special furring required in forming false beams, arches, cornices, coved ceilings, rounded corners, etc., and in preparing solid beams and posts for plastering.
Wherever a solid beam, post or lintel is to be plastered on wooden lath, the timber should be furred with strips at least inch thick to afford a clinch for the plaster, and on vertical surfaces these strips should always be put on so that the laths will be horizontal, as in Figs. 52 and 55. Where it is impracticable to use furring strips metal Path (such as expanded metal or the Bostwick lath) should be used, as in no case should wooden laths be nailed against a solid timber. Round corners in partitions should have the studs set not over 10 or 12 inches apart, and they should be bridged every 3 feet with solid bridging cut to the curvature of the corner. When the radius is less than 3 feet the laths are usually put on diagonally and bent around the corner. They should never be put on vertically. When the angles formed by the walls and ceiling are to be coved, or heavy plaster cornices are to be used, it is necessary to fur for the same by putting up boards cut to the shape of the cove or to the general shape of the cornice. These furring blocks or boards should be at least a full inch in thickness, and if very large, at least 1 ¼ inches thick. They should also be set 12 inches on centres, as the close spacing makes a much better job of lathing and a firmer ground for receiving the plaster. For plaster cornices the blocks should be cut so as to require as little stucco work as possible (see Section 349, Part I.) and'
Fig.188 - Elevation.
then lathed, as in Fig. 190. In forming false beams for plastering a skeleton is generally built, as shown in Fig. 191, which is suspended from planks B, B, spiked to the under side of the floor or ceiling beams above, or to blocks let in between them. If the beams are quite shallow solid blocks of plank may be cut of the proper shape to receive the lathing and nailed to the under side of the joists or to the cross-furring. Where the depth of the beam is 12 inches or more, however, the construction shown in Fig. 191 is much the best. If the beams are to be cased with wood solid blocking is generally employed for furring, as shown in Fig. 283.
False arches are usually formed in a similiar manner, except that the vertical pieces, being longer, should be 1 ¾ inches thick, and a curved rib should be cut to form the edge of the soffit and to receive the laths, as in Fig. 192.
The essential points in regard to all furring are that it shall be strongly secured and be put up perfectly straight and true. This is of especial importance in connection with beams and cornices, as any irregularity can not well be overcome in the plastering, and the least deflection is readily discovered by the eye. It is also desirable that the blocks or strips that receive the laths shall not be spaced more than 12 inches on centres. The exact shape of the furring for beams, coves, cornices, etc., should be shown by full-size details or large scale drawings.