I wanna say thank you so much for this video. Im a 42 year old man that new this years ago but with time my mind went, lol. After 3 minutes of your video it all came to me. Thanks again.
Hi he said you could either use the Swanson book of rafter tables, or your framing square using the rafter square the pitch is 9/12 so o your rafter square the top line of engraving in words reads common rafter length per foot run, so you look for the number 9 above this writing which is gives you the number 15 you then have to times this number but half the span of your build the span is 12 feet so half is 6 do times 6x15= 90 inches you then have to add the 1 foot over hang so add 90 inches to 12 inches and you get 102 inches you need to divide 102 by 12 inch to give you the length in feet so 102 divide by 12 = 8.5 feet so 8 foot 6 inch so he used a 9 foot board, hope this helps
So he said you could use either the Swanson table guide or use a rafter square, using the rafter square (The skinny length is called the tongue. The thicker, longer section is called the blade.) the pitch of the roof is 9/12 so using the blade look up the number 9 underneath you will find the number 15, you then times this 15 by 6 which is half the span of the roof and get 90, these numbers are in inches, you then need to add the hang over for the eaves and fascia board which was 1 foot or 12 inches add 12 inches to 90 inches gives 102 inches divide this by 12 to convert to feet and inches you get 8.5 or 8 foot 6 inch so he choose a 9 foot board hope this helps
you have to take the HAP (height above plate) in your birds mouth which is the vertical distance 90 degrees from the horizontal seat cut distance and add that measurement to your total rise of your ridge board, and then subtract 3/8 of an inch due to the ridge drop.
Hello, I use the speed sq. to layout my rafters. I having a very difficult time with the birds mouth! These are my measurements: 143.25 span...71-5/8 run...3/12 pitch...17.91 rise...73-13/16 diag. I make my 1st plum cut 3/12...measure down the board to 73-13/16 make 2nd plum cut...add10.5" for overhang. I come back to the 2nd plum cut...measure up 1-1/2 inch for the seat cut, then 3-1/2 inch cut. I finish off with cutting 3/4 inch for the ridge board...it doesn't fit!!! What am I doing wrong!!!
In a 15/12 sloped roof, under the fifteen it is 19.21 in per foot run. This means that for every foot traveling horizontally the rafter is 19.21 in Long.
