Durability of Stucco and Plaster

Progress, Volume XII, Issue 9, 1 May 1917, Page 958

Durability of Stucco and Plaster

In Conjunction with the Associated Metal Lath Manufacturers the United States Bureau of Standards undertook, in 1911, exposure tests of metal laths plastered with various metals, mainly for the purpose of determining the best methods of construction to ensure the protection of the metal from corrosion. These tests, which arc still in progress, proved that painted or preferably galvanised lath, embedded in dense, water-resisting plastering material, would not corrode. At the same time, some plastering materials were in themselves found defective, of course, and the manufacturers of lime, cement, gypsum, hollow tiles, metal laths, etc., suggested a conference of interested parties. As a result, a committee was appointed in 1914, consisting of .members of the Bureau, of representatives of the Supervising Architect’s Office of the Treasury, of the American Concrete Institute, of the industries and, further, of three experienced contracting plasterers. A test structure, 200 ft. long, 26 ft. wide, and 24 ft. high, was erected in the Bureau grounds, and fifty-six stucco panels, each about 15 ft. by 10 ft., were prepared, the building serving for the exposure of the panels and for the erection of plaster walls and partitions. When the panels were examined, in April, 1916, after six months’ exposure, only two panels were found entirely free of cracks; 40 nor cent, of the panels were considered satisfactory, but the majority were more or less deteriorated. The tests were rather discouraging, therefore, but it must be stated that in the panels a smooth type of finish, commercial!v known as “sand-float finish.” had been employed, which is more likely than the usual rough type of finish adopted by builders to bring out any superficial defects. The report contained in Technologic Bauer No. 70, which was drawn nu by Messrs R. J. Wilg, J. C. Pearson, and W. U Emley, does not draw any general conclusions, in view of the necessity of further experimental work. No recommendations are offered for stucco construction. The forms and construction of the stucco speck mens examined and their present condition are however, and it is intended to issue a further report dealing in particular also with various stucco structures which have been standing for five or more years. “Extravagance of anv kind, whether in the use of undnlv costlv material or excess of ornament, is as inconsistentwith refinement as anything approaching to the frivolous or gaudv.”— Belcher. “Well building hath three conditions—Commodity, Firmness and Delight.”— Henry Wniton .