MILL CONSTRUCTION BUILDINGS 



Minimum Building ordinances and insurance codes or speci- 

 Sizes of fications have established certain minimum sizes 

 Material of girders and thickness of floor plank. This 

 action tends to preserve the distinctive points of 

 mill construction, and separate it from ordinary light framing. 

 While all ordinances and codes do not agree in detail, the same 

 purpose is indicated in each. 



Girders or beams are commonly required to be at least 6 

 inches in either dimension, and often a cross-section area of 

 72 square inches is demanded. Some cities require 8 inches 

 as a minimum dimension. All timbers are to be planed on all 

 sides. 



The main or carrying floor should be at least 3 inches thick 

 with tongued and grooved or splined joints if laid flat upon 

 the girders. For plank 4 inches or more in thickness, the edges 

 should be grooved to take a %-inch by l^-inch spline. The 

 top wearing floor 'may be of a 1-inch material. All material 

 should be surfaced on all sides. The sizes given above are 

 nominal and not actual. 



Girders Although a minimum dimension of 6 inches (nominal) 

 is specified by building ordinances and insurance rec- 

 ommendations, girders of greater depth than width are com- 

 monly used. Formulas for finding the size of girder to carry 

 a given floor load will be found in a special section at the end 

 of this bulletin. 



Girders are preferably of single stick, but for sizes above 14 

 inches by 16 inches it is often advantageous to use two pieces 

 8 inches by 16 inches, or a similar combination, bolted together 

 securely side by side with the larger dimension vertical. It 

 has been the custom to leave an air space about %-inch wide 

 between the two members thus fastened, but modern practice 

 favors placing the two girders close together without air space. 

 It is claimed that the space between double members allows 

 the entrance of fire into a place which is difficult to reach with 

 the ordinary sprinkler system or even with a stream from a 

 hose. 



Bolts %-inch diameter fitted with nuts and 3-inch washers 

 are often used to fasten double girders. The extreme bolts are 

 placed about 2 feet in from the ends, while the others are stag- 



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