PLANNING THE SILO 49 



In order that any silo may fulfil its purpose, it is neces- 

 sary that the joints between the doors and the door frames be 

 air tight. It is difficult to obtain air-tight joints between 

 doors and masonry drawn out of shape, thus causing the loss 

 of as much as 4 or 5 cubic feet of silage at one door. Sealing 

 with clay was found to be satisfactory where reasonable care 

 was exercised in its use. This becomes a very simple matter 

 by taking a quantity of fine clay or other fine soil, wetting it 

 until sticky but quite stiff, and filling the shoulder of the 

 door frame with it before pressing the door into place. If 

 the mud is rather stiff it will hold the door to place until the 

 silage is up high enough to secure it permanently. The 

 moisture of the silage keeps the clay damp on the inside, thus 

 making it air tight. This is one of the oldest and best meth- 

 ods of sealing doors. It has been thoroughly tried and found 

 to be very satisfactory. 



Roof Plans. There is in some localities a general impres- 

 sion that a silo does not need a roof. In reality a roof is not 

 absolutely necessary but is very desirable. It aids very 

 materially in preserving the shape of a wood silo, and in any 

 silo it is important to reduce the amount of frozen silage and 

 to protect the feed from bad weather. Otherwise, with 

 changes of weather the character of the feed will change. 



In building a roof it is desirable to make as rigid a struc- 

 ture as is practical, at the same time obstructing the head 

 room as little as possible. It is quite common to use timbers 

 extending across stave silos from one side to the other. This 

 is entirely dispensed with in the drawing shown in Fig. 4. A 

 most economical roof for the wooden silo is generally made of 

 rafters placed about 7 feet apart at the cornice and extending 

 in to the center of the roof. Headers should be placed about 

 three feet apart between these rafters. On a 16-foot silo roof 

 with }/$ to J4 pitch, the rafter will be not far from 9 feet in 



