Hip roof

Hip roof

The hipped roof is shown in the picture,

and the nomenclature of its elements in the drawing.

It has four edge rafters

and additional rafters on two additional roof surfaces.

Determination of the length of edge rafters
In a right triangle with a base and height 30 cm the hypotenuse has 42,5 cm.

It means, that for everyone 30 cm of the length of the run the edge rafter will have 30 cm high at each 42,5 cm of running. If the roof slope is 15 cm on each 30 cm running distance, then the rafters will fall 15 cm on each 42,5 cm segment length.

How to read a rafter on an angle bar?
– use the table in the figure 75 i 95. The second line below the centimeter points line, which is marked as the length of the edge rafters of broken roofs on each 30 cm of the length of the run, determines the length of the edge rafter on 42,5 cm of running length;

– we find the height for each section of the length of the run of an ordinary roof rafter (not edge) on the roof angle, under the number on the second line we read the length of the rafters on 42,5 cm of running;

– we multiply this value by the whole number 30 cm of sections falling on the length of the run.

Example
Find the length of the edge rafter for the following roof:
roof slope (i) = 1/4 (14° or 25% or 0,25),
roof run (a) = 300 cm,
roof span (2 x a) = 2 x 300 cm = 600 cm.

Solution
– height at each 30 cm length of flight = slope x roof span = 1/4 x 600 cm = 600/4 cm= 150 cm : 10 (episodes after 30 cm) = 15 cm,
– the length of the edge rafter each 15 cm in height is 45,0 cm,
– the total length of the edge rafter is equal to the length of the edge rafter each 15 cm of the height of the run multiplied by the number 30 cm of the length of the run is equal to 45,0 cm times 10 pieces which equals 450,0 cm.