Question

The roof of the building shown below has a span of 48 feet. The rafters upon which the roof is laid are 30 feet long, including a 4 foot overhung. a. Knowing that the pitch of a roof is the ratio of the rise to the run, find the pitch of this roof. B. If the entire roofline measures 100 feet from end to end, find the total area of the roof. c. Find the percent of the roof used for the overhang

Answer 1

Solution :

Given :

Span of the roof = 48 feet

Length of the rafter = 30 feet (including the 4 feet overhung)

So, for the 30 feet long rafter, 26 feet will be rafter length from the high point of the roof to the edge of the roof and 4 feet will be the roof overhung.

Therefore, the horizontal span per rafter is

$=\frac{48}{2}$

= 24 feet

a). So the rise of the roof is $= \sqrt{(26)^2-(24)^2}$  

                                         = 10 feet

b). Pinch of the roof is $=\frac{\text{rise}}{\text{run}}$

                                     $=\frac{10}{24}$

                                     $=\frac{5}{12}$

c). The percent of the roof used as overhung is

     $=\frac{4+4}{60}\times 100$

     $=\frac{80}{6}$

       = 13.33 %