Calculating Gable Pitch Roof
I can show you how to calculate your roofīs pitch but my pragmatic piece of advice is:
donīt bother with it! Rather use this
roof pitch calculation tool">free roof pitch calculator that does it all instead of you.
Calculating pitch roof
Yes, the calculation of the roof pitch is an easy operation if you still remember all the laws of sines and cosines, triangle angles, hypotenuses, etc... If not, get back to school! Sounds like a torture for you? Again, I will explain shortly, how to calculate pitch roof but after understanding it, just use the free roof pitch calculation tool I offered above.
Determining the roof pitch
In order to determine the pitch of the roof, you only have to know (means measure first) these two dimensions (heights). The first is the height of the gable (G). Sorry for my English, if you donīt understand itīs the distance between the roof ridge top and the straigth line drawn between your eaves (or the upper parts of your gutters if you have no roof eaves). The second is the height (R) of the roof field (surface), which is the perpendicular distance between the roof ridge line and the line of your eave (upper part of gutter), again. To measure both of these distances you only need the measuring tape or a very sophisticated measuring tool called #plummet on the cord# (Pentium 7, Intel inside, at least). As soon as you get these two figures, go to the
free pitch roof calculation tool to calculate the pitch roof. No problem if you miss 1-2 inches (centimetres), in fact, it makes no difference, youīll usually measure a finished roof covered with shingles which themself represent some deviation, so again, donīt bother, this is no brain surgery. When using the
roof pitch calculator tool, it doesnīt matter if you use inches foots or metres. Just remember that G and R have to be added in the same units to get relevant result.
Mr. Pythagoras and your roof
The law of sines states that: If two sides and the angle opposite one of them are specified, then the angle opposite the other can be calculated. The third angle is then determined as the sum of the inner angles of the triangle have to produce 180 degrees (no way out for them). All and all it means that if we have the height of the gable (G) and the height of the roof surface(R) we can easily calculate the angle between the roof surface and ground (the roofīs pitch). If alpha is the angle (pitch) of the gable roof and gamma represents the 90 degrees angle (it does, donīt worry), the exact formula of gable roof pitch calculation is sin(alpha)=H/G*sin(gamma). If you are not from US or UK and inches and foots just confuse you, I have an easy way how to gauge the pitch roof and translate the 7 in 12 roof pitch (just an example) to degrees. E.g. 7/12 pitch represents arcsin of the 7/12 * sin(90) (the gamma angle, do you remember?) and you can repeat the formula with any x/12 roofing ratio. Letīs finish this math practice and, once again, just use the
free calculate pitch roof tool that does it all instead of you...
