GREENHOUSE CONSTRUCTION AND HEATING 29 
wooden plates because 
of their smaller size, 
durability and efficiency 
in preventing ice from 
forming along the 
eaves. 
Gutters are expensive, difficult to keep in repair, and 
being wider than eaves-plates they cast a larger shadow 
upon the plants in the greenhouses. Wooden gutters, 
similar to the one shown in Fig. 15, are in common use. 
They must be kept well painted in order to prevent rapid 
decay. Cast-iron gutters (Fig. 16) are more satisfactory 
than wooden ones, and should be used more generally. 
They are made in great variety, but drip grooves are 
essential features. 
Sash bars for the roof, sides and ends vary greatly in 
size and to some extent in shape. Fig. 17 shows typical 
forms of roof and side bars. The sash bars should be 
large enough to prevent sagging in any part of the house, 
but no larger than necessary, because of their obstruction 
to the light. Their size is largely dependent upon the 
strength and rigidity of the supporting structure of posts, 
purlins and braces. The 
sizes shown in the illus- 
trations are in gen- 
eral use. 
Roof.—The roof 
should not be heavier 
than necessary to se- 
cure proper strength, 
and it should be built 
in such a manner that 
there will be the least 
obstruction to light and 
sunshine. The pitch of 
the roof should receive 
. A Fig. 16.—Iron gutter with roof bars con- 
careful consideration. nected. Also shows connection with iron post. 
Fig. 15.—Wooden gutter. 
