STRUCTURAL MATERIAL 77 



Rafters. Their use is now confined al- 

 most wholly to all-metal frame houses which 

 are discussed in Chapter VI. 



KINDS OF WOOD 



Three kinds of wood are now being used 

 in greenhouse construction: Cypress, cedar 

 and California redwood. Of these the first 

 two are preferred on account of the higher 



Fig. 46. "Pecky" cypress 



cost of redwood. There is little difference 

 in the durability of cypress and cedar. If 

 well framed, and if thoroughly painted when 

 erected and at least once in two years there- 

 after, either will last a lifetime. 



Pecky cypress is the heartwood from old 

 trees. It is full of holes or "pecks" and is 

 often too "shaky" for sash bars and other 

 small members, but it is one of the most dur- 

 able woods known. It is used chiefly for 

 benches, and in other places where ordinary 

 lumber decays rapidly and where great 

 strength is not needed. 



