134 FAEM BUILDINGS IN SOUTH AFBICA 



An ordinary finish for a floor consists of 1 part cement to 2 parts 

 sand, applied in a layer from f inch to 1 inch thick. This requires much 

 more cement than does a granolithic finish. 



It is most important that any layer, such as plaster or granolithic, 

 should be applied while the base concrete which it covers is still 

 "green," in order to get as good adhesion as possible. Thus in laying, 

 say, a cow-byre floor, it is advisable only to lay as much in one day as 

 can be completely finished off and surfaced on that same day. 



The following description of the rendering of a vertical wall may help 

 to make clear the method adopted by the plasterer : — 



The "green" concrete of the wall is first scratched all over with 

 an iron spike, or the point of a trowel, so as to produce a rough surface. 

 The workman next proceeds to apply vertical strips of cement mortar, 

 about 4 or 5 inches wide, to the wall. These strips are spaced about 

 3 feet apart. The surface of the wall, where each strip is to be placed, 

 is wetted and painted with neat cement grout (i.e. cream of cement and 

 water) immediately before the application of that strip. 



The strips, having been applied to the wall, are next scraped off 

 plumb and reduced to the correct average thickness by the use of a 

 wooden straight-edge, a spirit-level being employed to test their 

 plumbness. These strips of mortar are called screeds ; they serve as 

 guides for the working of the remainder of the plaster between them, 

 a straight-edge extending from screed to screed being utilised for that 

 purpose. The surface of the wall between the screeds is wetted and 

 painted with neat cement grout, immediately before the application of 

 the cement plaster, as was done for the screeds themselves. In applying 

 the mortar, both for screeds and intermediate portions, the first of it 

 should be thrown on to the prepared surface of the wall ; by this means 

 effective adhesion is secured. 



The whole surface of the plaster is smoothed by rubbing it over 

 with a wooden float, and the final finish is given some time later, by 

 means of a steel float, when the plaster is hard enough not to stick 

 to the float and so be torn away from the base concrete. This trowelling 

 with a steel float brings the cement to the surface, thus producing a 

 dense hard face and increasing the water-tightness. 



Surfaces on which animals have to walk, should be rough finished 

 by brushing them over with a stiff brush while the face is still soft. 



Plaster should be sprayed twice a day with water, for about ten 



