GENERAL CONSIDERATIONS 49 



This formula is also applicable to an un- 

 even span roof provided the distance from the 

 point directly underneath the ridge to either 

 side of the house is known. For example : In 

 a 2O-foot three-quarter span house, the base 

 corresponding to a of the triangle A B D in 

 Fig. 24 is either two-thirds or one-third of 

 20 feet, according to which side of the roof 

 we wish to measure. 



In the following table will be found the 

 lengths of rafters required to form roofs of 

 various angles on houses of different widths. 

 The figures in the left-hand column corre- 

 spond to half the width of an even-span house 

 or the horizontal distance from the eaves to 

 a point directly underneath, where it is de- 

 sired to place the ridge. 



Table giving length of rafters necessary to form roofs of 

 various angles on houses of different widths 



