CONSTRUCTION NOTES 285 



tions of planting pockets in different kinds of walls are shown in the accom- 

 panying plates of photographs. 



Free-standing walls. Free-standing walls are usually constructed of 

 stone (Plate 117, figure 4), of brick (Plate 117, figure 2), or of wood 

 covered with plaster upon expanded metal (Plate 117, figure i). Such walls 

 as are shown on Plate 117, and Plate 116, figure 5, are usually faced on 

 both sides. The appearance of the wall depends very much upon the proper 

 height and upon the proper line and grade at the top and bottom of the wall. 

 The foundation for any free-standing wall should extend to a point below 

 the line of normal frost action (see Plate 117). Any differences in grade 

 at the base of the wall should be taken up by a stepped foundation. 



Concrete footings are the most desirable type for these walls, although 

 stone and brick may be equally desirable if reinforced occasionally with 

 longitudinal steel bars. The thickness of the footings depends somewhat 

 upon the load produced by the wall superstructure. Walls constructed of 

 wood on which a surfacing of plaster is applied to expanded metal, will 

 not need continuous foundations. The foundations of concrete should be 

 constructed at the piers as shown on Plate 117, figure I. Exterior plaster 

 is usually applied in three coats. The first coat or scratch coat should be 

 thoroughly trowelled into the depressions of the wall which have been 

 brushed thoroughly clean and moistened with water. The plaster is scratched 

 or roughened with a saw-toothed paddle or other suitable tool before it has 

 hardened. The first coat is rich in cement, the second, browning or inter- 

 mediate, is much leaner in cement. It is applied over the well moistened 

 scratched coat. The surface of the wall is straightened after the second 

 coat has been applied. The finish coat is applied on the second coat and 

 finished according to the texture and color desired. If the wall is to have 

 a pebble finish the aggregates are added after the finish coat has been 

 applied. The second and finish coats should not be permitted to dry rapidly, 

 but should be sprinkled frequently after the mortar has set, or protected 

 by wet burlap hung over the wall. 



Plastering should be carried on continuously in one direction. The 

 second coat should be applied the day after the scratch coat. The finish coat 

 should not be delayed more than a week. In plastering on concrete which 

 has already attained a hard set, it is best to apply a bond coat before any 

 plastering is attempted. There are several patented bonds or binding 

 coats on the market. A neat cement slush put on with a brush will give 

 fairly satisfactory results. This should be applied just before plastering 

 and the plaster applied before the neat cement has started to dry. When 

 the rough coat finish is applied to concrete it is not usually necessary to 

 put on a plaster coat. It is sometimes cheaper in the construction of double- 



