STRUCTURAL MATERIAL 69 



serve the same purpose as glazing bars, ex- 

 cept that they are so milled that they will 

 take the glass from both the sides and the 

 ends of the house. One is used at each 

 corner. 



Side Posts. These posts bear the weight 

 and side strain of the roof. They may be 

 of wood, gaspipe, or structural iron or steel. 

 Their size will depend on the height of the 

 wall and the width and construction of the 

 house. Wood posts 4x4 inches, 2 or 2/^2- 

 inch gaspipe, or /^ x 3-inch structural iron 

 or steel are usually considered amply strong 

 for most houses. The gaspipe and steel 

 posts are usually set in concrete and mason- 

 ry. It is best to set the wood posts in the 

 same manner. Occasionally the structural 

 steel posts are bolted to iron sills which cap 

 a concrete or masonry wall. 



Sash Bars. The sash bars are among the 

 most important of all the members which go 

 to make up a greenhouse. They must be 

 strong enough to carry the weight of the 

 glass, yet be of such form and size as to 

 cast the least possible shade. They are 

 of various forms and sizes. Bars made en- 

 tirely of metal are seldom satisfactory for 



