286 PARKS 



faced rubble walls, when the material is not very expensive, to make a thick- 

 ness approximating twenty inches in order to save the expense incurred 

 by dressing the stone if each stone were to extend completely through 

 the wall. 



Where a wall is partly retaining and partly free-standing (Plate 116, 

 figures 4 and 5) it is very necessary to exercise extreme care in the wall 

 construction in order to provide a continuous even surface on the face 

 toward the lower level. If a brick or hollow tile wall is constructed as 

 shown on Plate 116, figure 4, damage from surface drainage will occur. 

 This damage may be avoided by a type of construction as shown on Plate 

 116, figure 5, where the tile or brick is carried below the ground surface 

 on the lower side of the wall and where the concrete foundation is carried 

 slightly above the ground surface on the upper side of the wall. 



In the construction of all brick or hollow tile walls it is necessary to 

 keep the water out of the joints and, therefore, a proper coping should be 

 placed on the top of the wall. This coping should preferably project slightly 

 beyond the face of the wall and the top should be given a definite slope 

 in order to shed water. A drip groove should be cut in the under surface 

 of the coping whenever possible. It is not advisable to veneer a free-standing 

 wall. It is more economical to construct a thirteen-inch wall than to con- 

 struct a six-inch reinforced concrete wall and subsequently to veneer the 

 concrete with stone or brick. In the construction of all walls, whether they 

 are constructed or veneered with brick, or whether they are plastered with 

 stucco, a definite water table should be provided approximately one and 

 one-half inches above the finished grade. There should be a waterproof 

 joint of some suitable mastic between the veneer or stucco and the con- 

 crete shelf or foundation below in order to prevent soil moisture from rising 

 and discoloring the wall. This is very desirable in the construction of 

 hollow tile or brick walls the surface of which is to be plastered. 



Retaining walls and free-standing walls. Cost data. The author has pro- 

 cured from time to time cost data information with reference to various 

 items of labor involved in the construction of different walls. 



Boulder retaining wall. The stone for this wall was gathered on the 

 job, from a distance of one to one hundred yards. The wall averaged 14 

 inches thick and the stones ran from large at the bottom to small at the 

 top. A foundation trench one foot deep was dug. There were 145 cubic 

 feet of wall and the time required per cubic foot was approximately one-half 

 a labor hour. 



Stone wall on concrete footing. This was built from stones with a sur- 

 face area of one to two square feet and two to three inches thick laid with 

 a mortar joint of one-half to three-fourths inches. The wall was 39 feet 



