CONTINUOUS DOORS FOR SILOS. 



87 



The vertical jamb forms may be made in sections of any con- 

 venient length, preferably from six to twelve feet. 



Fig. 29. Continuous Doorway, with concrete jambs, showing man- 

 ner of anchoring to the vertical reinforcing, and position of 

 plank doors. 



Courtesy Universal Portland Cement Co., Chicago. 



Care should be taken to have the wooden forms absolutely 

 vertical. All surfaces of wood which will come into contact with 

 the concrete should be planed and oiled, which will insure a 

 smooth surface and prevent the wood from adhering to the con- 

 crete. Full illustrated details regarding constructions of this 

 kind will be found in catalogs issued by several cement manufac- 

 turers. 



Local conditions largely govern the cost of concrete silos. The 

 ruling factors are the price of gravel and cement and the cost 

 of labor. An investigation was made during the spring of 1911 

 by a large concrete manufacturing company to ascertain the 

 actual cost of 78 monolithic silos scattered through Minnesota, 



