=40.= Although not always of a brick or terra-cotta nature, it will be found more convenient to consider all =tiling= together and at the same time that the cost of brickwork is taken up. Only very general figures can be given on the cost of tiling, as this cost depends considerably on the design to be carried out. The cost per square foot of various styles of tile laid in place is as follows: Moravian tile floors $1.50 Interlocking, rubber tile floors 1.50 Columbia marble tile, 12" × 12", with colored border, tile laid straight on floor .50 Columbia marble tile, 12" × 12", with colored border, tile laid diagonally on floor .60 Italian marble tile, 12" × 12", with colored border, tile laid straight on floor .70 Italian marble tile, 12" × 12", with colored border, tile laid diagonally on floor .80 Terrazzo and marble mosaic border .38 to .40 Common, white tile in vertical locations, as lining for elevator shafts, etc. .40 Marble mosaic ceiling work 3.00 Marble and glass mosaic ceiling work 8.00 2-inch book tile (laying only) .04 3-inch book tile (laying only) .04 Shoe tile (laying only) .06 MACKITE =41. Mackite= is a fireproofing material used for partitions in very much the same way as terra cotta. As this material is put in place by bricklayers, its cost will be taken up here. Where there are many openings, two bricklayers and one laborer can set 240 square feet of mackite in 8 hours; in a straight wall, without openings, these same men can set about 400 square feet. The market price for 2" × 12" × 30" blocks is 6 cents per square foot; for blocks 3 inches thick, it is 8 cents per square foot. The average price for both material and labor for 2-inch mackite is 10 cents per square foot; for 3-inch material it is about 12 cents per square foot. CARPENTRY =42. Carpentry= should include general framing, roofs, floor joists, partitions, sheathing, flooring, furring, and plastering grounds. =43. Board Measure.=—The rough lumber used in framing is measured by the =board foot=, which means a piece 12 inches square and 1 inch thick. Lumber is always sold on a basis of a thousand feet =board measure=. The customary abbreviation for the latter term is B. M.; that for _thousand_ is M. Thus, 500 feet board measure, costing $27 per thousand, would be written: 500 ft. B. M., at $27 per M.