With a 10 foot wide shed with a 33 degree roof, how long is rafter from ridgepole to top of bird's mouth?

Question

it's a 8" roof pitch, we have a square but no book, isn't there a formula for calculating this?

i know the run is 8" to a 12" rise. the peak is in the middle of the 10 foot wide building, so is there a formula for calculating the rise measurement over a 5 ft. run at this angle?

Answer 1

somwhere about 6' 4 on an 8/12 roof a squared + b squared = c squared

Answer 2

Hi Linda,
There is a formula but if comes with a book when you buy a framing sq..the best way to commplete this is to try the long point formula this is as follows i use it ever time.
you will need the following :
a speed square small triangle with degress on it
skill saw

Now with ridgeback in place being a ten ft wide building
ridgeback is in the center @ 5 ft
add 12inches for over hang
hopfully you used ceiling joints running side to side
take a roof rafter it should be about 8 ft now raise it to the the ridgeback at the end and draw a line vertical on the roof rafter. this will give you your angle
nornally you can make your over hang any length 12 to 14 is norm,
cut the line the long angle of that board to the length you want
example measure from the long point of that cut down the same side to your length wich i thing would be about 73 or 75 inches
mark it , Now now take the cut off piece and use it to draw you angle BUT flip that board over thes two angles go opposite each other , YOur long point at the ridge is UP and the long point at the soffeit is down. Good luck
JIM

Answer 3

Rafter "Rake" is never referred to in degrees of angle. It is expressed in rise and run, such as 4" in 12", or 6" in 12", 12" being the run and 4" or 6" being the rise. With that information in hand you can purchase a "Framing Square" with a book this will give you all the information you need for your "Rake" dimensions.