Hip Roof Multiplier

The following table provides the roof pitch multiplier for roofs of various slopes.

Hip roof multiplier.

You can see from the plan that the total run of a hip rafter is the hypotenuse of a right triangle. 800 multiplied by 1 16. Hip rafter ratio length multiplier hrrlm 18 12 1 5 common rafter length multiplier crlm 13 4164 12 1 11803. Simply locate a roof rafter board place the end of the level against the bottom edge and measure from the 12 inch mark vertically to the bottom edge of the rafter.

Repeat the run not the length of a common rafter for precision the thickness of the ridge board and any eave. Multiply step 1 and step 2 i e. The more you practise the more familiar you become using these functions. On a hip roof framing plan the lines that indicate the hip rafters ec ac kg and ig in figure 18 3 form 45 angles with the edges of the building.

For high wind areas or strong storms a pitch of 4 12 6 12 18 5 26 5 angle is recommended. Roof framing geometry kernel rafter lengths roof ratio multiplier. A 12 in 12 pitch is a steep 45 degree angle roof. Hip roofs can offer extra living space when a dormer crow s nest is added to a hip roof.

Divide the rafter length by 12 of run to calculate the roof ratio multiplier. For example if you measure 4 inches the pitch of your roof is 4 12. A roof s pitch is determined by how much it rises vertically for every foot it runs horizontally. Find the value of 7 12 from the roof slope multiplier table which is 1 16.

Students should use the sin cos and tan funtion rather then the multiplier table to calculate the length of the roof members. For a more detailed explanation of the roof pitch multiplier see how to find the area of a sloped roof if you know the roof pitch in degrees find the secant of the slope using a scientific calculator for example if the roof pitch is 45 then sec 45 1 414213. If the home measures 20 x 40 and has a 7 12 roof then to calculate the slope of the roof follow these steps. See the image below for more explanation on rise run and pitch.

Thus a moderate 6 in 12 roof pitch means that the roof rises 6 inches vertically for every 12 horizontal inches it runs. The two shorter legs of this. If you re putting down new roofing materials on your home or another building with a hip roof your first step will be to find the exact dimensions of each of the roof s individual faces then use those measurements to calculate its total area in square feet. This will give you the rise over run or pitch.

For regular hips and valleys where the roof sections have the same slope and meet to form a 90 degree angle. Multiply 20 and 40 which equals 800. It takes some time to get use to these functions. The common rafter length can be calculated by the roof ratio length per 12 of run.

Remember practice makes perfect. The value arrived at 928 reflects the square feet of the roof.