Roof Pitch Factors

Trying to frame a new home, shed, garage or some home construction? The most important part of the house is the building roof pitch and you need to buy matching roofing shingles to finish a job well done. For this you need to calculate roof pitch accurately. The roof pitch is a term that is used to determine the roof pitch slope of the sides of the roof surface or the inclination of these sides. This measurement is in respect to a horizontal plane or a surface that is totally flat and parallel to the horizon. The roof pitch may vary almost infinitely and it must be absolutely vertical or inclined at any angle between the above two limits. Know more on, how to build a porch roof.

There are many ways to determine roof pitch and the best way to calculate roof pitch accurately is to give the range at which the roof surface will make a horizontal plane. Thus, thirty degrees, forty five degrees or sixty degrees, help make a building roof pitch that is in a horizontal plane. This system is used by civil engineers mostly and carpenters and architects use a different system generally. Let us look in detail at the roof pitch factors.

Determining Roof Pitch Factors

It is very important to determine roof pitch factors before calculating the roof pitch estimate. The roof pitch factor will help in figuring out the exact roof estimate. In order to calculate roof pitch factor, determine the inch the roof will rise for every 12" it runs or spans. You need to first determine the dimensions of the roof by multiplying the length with width, to calculate the square footage. Know more on roofing costs and estimates.

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To determine the roof pitch you need to place a level across the top ridge with a 12" mark that rests directly above the center top of the ridge. Be sure to level the level. Take measurements from the surface of the roof to the bottom of the level. The inches that you get as reading is nothing but your roof pitch. For example, when your tape reads 7" it means the roof pitch is 7/12. If there are existing roof layers, then determine roof pitch by the thickness of these layers of roof that protrude above the roof sheathing. Add this amount to the tape measurement reading. For example, the roof layer that protrudes above the roof is 1" so add 1" to your tape reading. That is, if your tape reads 7" then add 1", that will give you 8/12. Then multiply the square footage with the roof pitch factor to get the total area of the roof.

If you do not wish to climb up on the roof to calculate roof pitch, then use a ladder. You can calculate roof pitch from the rafter tail bottom or at a barge rafter at the gable end on the roof over hangs. The procedure to follow is the same. This gives a more accurate reading as the layer of roofing does not need to be compensated.

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Roof Pitch Formula

The roof pitch formula is as follows:

• Place a level against a roof.
• The point where the level touches the roof, measure 12" that is called the run.
• Then from this point down the roof, measure the distance in inches. The number obtained is called the rise.
• Thus, the roof pitch factor will be expresses as rise over run, that is 7/12.

Roof Pitch Factor Chart

Roof Pitch	1:12	2:12	3:12	4:12	5:12	6:12	7:12	8:12	9:12	10:12	11:12	12:12
Roof Pitch Slope Factor	1.0035	1.0138	1.0308	1.0541	1.0833	1.1180	1.1577	1.2019	1.2500	1.3017	1.3566	1.4142
Valley and Hip Factor	1.4167	1.4240	1.4362	1.4530	1.4743	1.5000	1.5298	1.5635	1.6008	1.6415	1.6853	1.7320

This is some information on roof pitch factor. I hope you have understood the roof pitch formula, how to calculate roof pitch and the roof pitch factor chart. This information on roof pitch factor will sure prove to be helpful to you while building a roof.