Hi, I was in the process of cutting some 2″ x 10″ rafters for a friends place this weekend and, I don’t understand how to make my heel cuts. I looked-at my spped square “how-to” book and I came to the conclusion I am brain dead on how to do it w/o scrwing everything up. Years ago I did it, but I guess age has already caught-up w/ me. I prefer the framing square over the speed square to do this.
I am trying to get a 6:12 roof. When I mark the ridge for 6:12(plumb-cut) I am fine there. BUT, I get completely lost after I mark the heel @ the 6:12 plumb, aligned w/ the exterior wall then try to figure-out how to notch the seat. My confusion is once I notch the seat, the 6:12 is increased to whatever, thus throwing-off my plumb cut.
What the heck am I doing wrong in my miss-understanding?
Thanks for any help.
Tony
Replies
Hi Buster. I perfer using a rafter square rather than a speed square...but here goes.
First, do remember to shorten the overall rafter length (from ridge to wall exterior) by 1/2 the thickness of the ridge board.
That being said. place the speed square on the rafter stock edge, rotate at the pivot point until the correct roof pitch number ( 6 for 6/12) is lined up on the "common" side of the square, and mark your line along the pivot side of the square . ( Note* the "pivot" side of the square is normally the 90degree or straight side of square)
This mark is your ridge plumb cut line. Now measure down from top edge of ridge line to your actual rafter length...use speed square in same exact manner and this time mark the heel plumb cut line. The seat cut line is perfectly perpendicular to the plumb heel cut line.Set your speed square's 90 degree edge right on this plumb heel line and mark the other 90 degree edge for the actual seat cut . Measure up the plumb heel cut line 1-1/2 inches from the bottom edge of the rafter, then draw your perpendicular seat cut line ( which should measure approx 3-1/2 inches across for a 2X4 top plate. You can measure up more on the plumb heel line if need be, and then draw the seat cut. Whatever distance works...after cutting the seat cut and trial fitting the rafter...once set, measure the distance from top of plumb heel to seat and use that measurement to mark all future seat cuts.
Hope this helps.
Davo
Thanks to ALL of you for your helping me through my "brain-fart". I swear sometimes I have to wonderabout myself. I appriciate everyone's input and concern for doing things right. What a great site for help.
Dude, easy way...
Take a decent piece of 1/2-3/4 ply with a nice corner, measure 12" on one side, 24" on the other, draw straight line from point to point, cut it, center the edge of the triangle piece with a piece of 1x2 or 1x3 or 3" wide strip of ply to the edge you just cut and screw it together.
Butt it to the rafters edge and you have your plumb and seat and tail cut angles all on the same jig.
Its reversable and flipoverable so you can't scew up.
I draw a small pic of the rafter and pertinant dimensions on it so you dont keep remeasuring or looking on the wall for your dimensions(I wright on my walls, yes and you cant stop me!!!)ha, ha!
Keep the jig for tails and if you are using ceiling joists parallel to the rafter , you can use it to mark the angle so they dont poke out of the roof.( hard to sheet...you laugh now but wait till you show up the next day and have to break out the sawzall! yep, top notch guy i got werkin for me!)
you'll be a pro at it on the last rafter, BTW I use a little known tool called a hand saw to finish my beaks, the little funny lookin short one by stanley, cant 'member the name of it though, anyway, hook it on a nail on your horse, saves about 18.5 secs on your rafter cuttin' time Woo-hoo!
Keep hackin' and whackin'I cut the board twice and its still too short ! ! !
Edited 10/10/2005 2:37 am ET by LEMONJELLO
"BTW I use a little known tool called a hand saw to finish my beaks, the little funny lookin short one by stanley, cant 'member the name of it though, anyway, hook it on a nail on your horse, saves about 18.5 secs on your rafter cuttin' time Woo-hoo!"What's a "Beak"?Is it the inside corner of the birdsmouth? If so, why would you use a handsaw and not just over cut it with a circular saw? Just curious.Joe Carola
O.K. the 18.5 secs was supposed to be a joke..not funny I guess.Birdsmouth, birdsbeak, same difference (actually a habit from the old man) like a
"tape measure" vs a "measuring tape". Actually I think it might come from shape of the off cut?!?Same with the overcutting, I was taught as a kid that it was a No-No and have yet to have any refute this point much either way. I've had many garage meetings regarding this matter and posed it to inspectors here and I get "either way is ok, i guess" , doesn't inspire confidence.I cut the board twice and its still too short ! ! !
I wasn't saying anything about your 18.5 seconds and I know you were joking. I just wasn't sure what the beak was and why you would use a handsaw to cut rafters and now I know. There's nothing wrong with cutting a birdsmouth with a handsaw except that it takes 500 million times longer than a circular saw.....;-)
Joe Carola
Buster,
Use your framing square for the rafter PATTERN it's a lot easier and faster to use. Once you have your length deducting for half the ridge thickness no matter what way you figure your length whether it's stepping off or math. If you step off hold the square on 12/24, it twice as fast. I used a 2x4 wall for the drawing.
1)Hold the square on 12/24 with 12" at the top right side for example in my drawing scribing the 12" side for the top plumbcut.
2)Mark your rafter length to the outside wall and set the framing square the same way as you did the top plumbcut on 12/24 and scribe the 12" side. Without moving the square mark your overhang length and plumbcut.
3)Flip the square over from left to right with the 12" sliding over on your outside wall plumbcut mark and slide the square along that line until your level cut on the square reads 3-1/2" for your seatcut.
4) Slide the square over to the overhang plumbcut and move up or down until you have your desired fascia cut height and then scribe your level soffit cut.
Once you've cut the rafter you use that as your patter by tacking a 12" 2x4 block or 5/4 flat at the top where the plumbcut is and a 2x4 block at the top where the birdsmouth and overhang is and just use that as your pattern to slide on top of all your rafters until your blocks hit the top and scribe your top plumbcut and your birdsmouth and overhang.
THANKS FOR THE HELP!!
I needed a "refresher" course on framing "101" and all your help is appriciated! Framer..thanks for the drawing...Helps.
Any time Buster.Joe Carola
And how it "saves 18.5 seconds per rafter"?If it were easy....a caveman could do it.
A couple of days ago you posted a diagram showing how to properly measure and figure out rafter cuts. It included the angles and lengths between the ridge and plate( not the graphic that you posted in response to this question ) Now I can't seem to find it. Would you be willing to re-post it? It was about as good an explination of this as I have seen.
Thanks.
Terence
Are you talking about this thread?http://forums.taunton.com/tp-breaktime/messages?msg=64231.1Joe Carola