MILL CONSTRUCTION BUILDINGS 



gered at equal spacing along the length. The spacing lon- 

 gitudinally should not be greater than four times the depth of 

 the girder. 



Where girders meet at the columns, they should he fitted 

 around the column or butted up close to it. The ends of girders 

 may be drawn together closely by dogs driven into the top side, 

 or held in place by steel or iron straps spiked, bolted, or secured 

 by lag screws, as shown in Fig. 1. If the style of post cap 

 will allow, the sides of the post cap which project upward may 

 be used as straps for the girders. 



Floor Timber 



Casf/ron WQ!/ 

 Plafe 



Fig. 2. Method of Supporting 

 Girder on Wall Plate. 



Fig. 3. Wall Box for Holding End 

 of Girder in Wall. 



The length of the bearing at the ends of girders should be 

 such that the bearing area will be sufficient to allow a suitable 

 unit stress in compression across the grain of the wood. A 

 minimum length of 5 inches is often required, but an exact 

 determination should be made after the width of girder is 

 known. Methods of calculation and values of unit stresses for 

 compressive strength of timber will be found in a section at 

 the end of this bulletin. If the local building ordinance speci- 

 fies definite values, they should be used in all calculations. 



Girders are supported at the wall by metal wall plates or 

 wall boxes built into the wall as shown in Fig. 2 and Fig. 3, 

 thus distributing the loads more evenly on the brickwork. Wall 

 plates should have two flanges one to anchor the plate to the 

 wall, and the other to hold the girder on the plate. Care should 

 be taken to see that a i/^-inch air space is left around the ends 

 of girders for ventilation, so as to prevent the appearance of 

 dry rot. A preservative treatment applied to the wall ends of 



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