How to calculate the length of roof rafters (captioned)

When building a roof, how do you calculate the length of the rafters? All you need to know are the span of the building and the slope of the roof.

[@dwightemorgan4367]

this was the clearest explanation of rafter calculation. well done

[@MrRainbird12]

this is the best explanation yet!! Thanks !!

[@pinarellolimoncello]

Just a bit of feed back but the when it came to the crucial part of the maths and fully understanding it you speeded up the video, I think anyone trying to learn how to do this wouldn't pick up on where you've gone with the maths. In the past I've struggled with it and part of that is you obviously can't decimalise feet and inches, not easily. Say if it was an extension on an old house and the rise just happened to be 8ft 6 and 3/4 inches, the calculations are all getting a bit tricky, better to slow down the video at the difficult part not speed over it.

[@filsolano5465]

I was under the impression that he was gonna figure out the rafter length w/o using the calculator, by using the square alone. Great video tho. Thanks for posting.

[@evalunalopez8959]

good video