62 PRACTICAL SILO CONSTRUCTION 



crete, pressing it well against the laih to press 

 through and form a secure key. This should not be 

 less than l|"in thickness, and is best at about 2" or 

 2J ". The rafters must be spaced close enough so 

 that the metal lath will not sink or bend under the 

 weight of the concrete placed, or they may be rein- 

 forced by heavy wires stapled to the rafters every 

 6" apart around the roof for the first 3' from the 

 eaves upward. 



Before the plaster coating is applied, a thin wood 

 strip may be nailed to the butt ends of the rafters as 

 a fascia or finishing strip to the roof. This must be 

 thin, so as to bend easily to the circle. In placing the 

 concrete plaster, this strip will be of value in getting 

 the eaves or edge of the roof even and symmetrical. 

 The concrete for the roof will give the best satis- 

 faction when made in the proportions of 1:3, using 

 sharp, well-graded sand. 



ORNAMENTAL ROOF OR WALL FOR SILO 



At Fig. 17 is shown an ornamental wall for the 

 silo that extends above the top of the roof. This is 

 in the form of a parapet, with embrasures and 

 merlons molded to suit the wishes of the builder. 

 The diameter of the parapet is 4 inches more than 

 the diameter of the silo. This requires a 2 " strip 

 to be placed at the bottom of mold for parapet, as 

 shown in illustration (Fig. 18). The inside mold for 

 this part of the wall is 4 " more in diameter than the 

 silo, thus molding a 2" ledge entirely around the 



