While the plastering and concreting are drying out the finished fireplaces are usually built These are to be of bricks and should be built with a splay of from six to eight inches to the sides. (See Fig. 34.) The back lining is built up plumb for about six courses and then inclined toward the front until an opening of only about two inches is left. (Fig. 42.) If a flat arch or level bricks are used for the opening there must be provided a wrought iron bar, or better, two bars which must be let up into the under side of the bricks so as not to be seen. Care must be taken to see that fireplaces are set in the exact center of chimney breasts and rooms, and also that the face of the bricks are set in the required position, usually flush with the plaster line, although this may be varied to allow for differences in the form of mantel desired.