Although some experts recommend that, for stability, a concrete floor should be laid in three layers, the upper and lower of strong-material, having the bulk of rougher material between them, this plan is not followed to any great extent, and the utility of the intermediate course is doubtful. In order to make a strong homogeneous concrete, the voids in the aggregate must be filled with some finer material; it would be an improvement if the material intended to form the first two layers were incorporated and laid as one. The finishing coat may, if desired, follow closed upon the laying of the rougher material, but it will be better if the bulk is allowed to set first; and three days afterwards will be a very suitable time to finish off the floor, provided there is no need of hurrying the work forward. After the fine stuff has been ruled off, as soon as the surface begins to get firm, is the proper time to commence finishing-off; if this is commenced too soon, an unequal surface will result, whilst if the stuff is left to get too firm, the surface will be rough and patchy.

A hand float should be used at first, and with this the work should be beaten lightly, or patted until the " fat" appears; then trowel off with light strokes until the desired face is obtained.