CONSTRUCTION DETAILS— WALLS 



41 



sand and three parts crushed stone or gravel. The overflow opening 

 should be located twelve to eighteen inches above the bottom of the 

 basin so as to provide below it a space in which debris may collect. 

 This opening should be protected as shown in Fig, 41. If made of 

 brick, the walls should be about eight inches thick and the brick 

 should be laid in a strong cement mixture. The brick floor, however, 

 should be laid dry to permit seepage. On steep grades catch basins 

 should be installed at intervals of fifty feet, to prevent surface wash- 

 ing; on more gentle slopes 150 feet apart is sufl&cient. 



Walls and Wall Building 



WALLS may be divided into several classes according to mate- 

 rials used. As a rule they are made of brick, concrete, 

 stone or wood. Brick walls are used extensively through the South 

 as they are not affected by frost. Many retaining and fancy walls 

 are made of brick. Concrete has come into vogue of late and is used 

 considerably for rough walls and retaining walls. Stone is probably 

 used for general wall building as much as any other material, as its 

 utilization can be developed in many ways. 



TERMS USED IN WALL MAKING 



Walls proper are divided into two parts — a suhwall and a super-wall. 

 If a wall has two faces the portion in the center is called the filling. 

 Stretchers are the material of the principal surface of the wall laid 

 lengthwise of the wall. A header is a piece that goes crosswise to rein- 

 force the wall (Fig. 43). Quoins (Fig. 46) are pieces at the corner for 

 binding. A voussoir is a keystone or wedgestone in the center of 



COP17SG 



£>AJ-0-STRADr 



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Fig. 43.— Front view of part of a brick retaining wall to illustrate the various parts 



