I enjoy working with wood and building projects in my backyard. I know the basics for run and rise for my rafters but this is so much more involved. I too will have to watch many more times before the math sinks into my layman's mind. I do enjoy nice tight fits on my lumber cuts....so I may not get it on my first viewing but a good video which I'll watch time and time again until I get the math down tight.
I love this video. With that said...this sounds like an architect or an engineer way over complicating how this actually goes down on a job site. You know the pitch of the roof is a 9-12. You know the rise and run. You'll know the height of the ridge beam. You already can account for the diagonal. So say you are using 2x10 for rafters. You measure from the inside edge of the ridge beam diagonally down to the outside edge of wall framing. Now you lay your 2x10 on the saw horses, crown up and cut a 9-12 on the end. You take a tape measure using the number you got from the ridge beam to outside of wall Fram and measure from the long point of the 9-12 you just cut. Pencil and tape measure together, you scribe a line at that measurement. It will look like an "arc." It's common is residential framing to mimic a 2x4 after the birds mouth on a hand cut rafter. So now you scribe a line 3 1/2" from the top edge of end of the 2x10 up to the "arc" line you made. Where those lines meet is the inside of the birds mouth cut. Bam! Cut the birds mouth out, cut along the 3 1/2" line. You can install the rafter at this point. Or you can use this rafter as a "pattern" and have a guy cut out as many as you need. When all the rafters are nailed in, you can measure out from the building 1' 4" or whatever your plans say and mark the rafter on each end of the roof. Snap a line. Now, even if the wall is not perfectly straight, your rafter tails and fascia will be. Also, if the roof is going to have "ridge vent," the ridge beam will be lowered a little to allow air flow. You will need to account for that on the top of the rafter after you make your 9-12 cut and before you mark for the bird mouth.
Thanks for your reply. The VelociRafter series was created to teach how to use math to solve some common roof framing questions, especially for complex roofs. I personally found that by preparing my cut list prior to picking up my saw, I could dramatically reduce the amount of time it would take me to frame a roof. If your approach works for you, thanks great! Another idea for allowing venting at the ridge is to hold back the plywood an inch or so from the ridge vent.
Wow this is a great video. I will have to look at it several times in order to absorb all the info. Hope all this is on your website. I plan on looking at it because I plan on building a 24' x 24' storage barn with a gambrel roof. Thanks, very helpful
Explain how the cut of the bridsmouth doesn't affect the end angle cuts? If you look at your drawings and make the ridge cut and building line cut then make the birdsmouth cut , you change the angle of the end cuts.
R&R Homestead yes, he makes reference to a ridge beam and the plan call what looks like a ridge board a ridge beam. But no big deal, he’s not talking about the the difference each makes in roof dynamics. The rafters are cut and stacked the same and this vid is meant to show us the math involved. Which I can appreciate, but I know what you mean.
First roof rafter explanation I’ve watched that is mathematically accurate. Well done. 👍
The video is very well done with a lot of basic information. Great simple dialogue. Thanks.
I enjoy working with wood and building projects in my backyard. I know the basics for run and rise for my rafters but this is so much more involved. I too will have to watch many more times before the math sinks into my layman's mind. I do enjoy nice tight fits on my lumber cuts....so I may not get it on my first viewing but a good video which I'll watch time and time again until I get the math down tight.
I love this video. With that said...this sounds like an architect or an engineer way over complicating how this actually goes down on a job site. You know the pitch of the roof is a 9-12. You know the rise and run. You'll know the height of the ridge beam. You already can account for the diagonal.
So say you are using 2x10 for rafters. You measure from the inside edge of the ridge beam diagonally down to the outside edge of wall framing. Now you lay your 2x10 on the saw horses, crown up and cut a 9-12 on the end. You take a tape measure using the number you got from the ridge beam to outside of wall Fram and measure from the long point of the 9-12 you just cut. Pencil and tape measure together, you scribe a line at that measurement. It will look like an "arc." It's common is residential framing to mimic a 2x4 after the birds mouth on a hand cut rafter. So now you scribe a line 3 1/2" from the top edge of end of the 2x10 up to the "arc" line you made. Where those lines meet is the inside of the birds mouth cut. Bam! Cut the birds mouth out, cut along the 3 1/2" line. You can install the rafter at this point. Or you can use this rafter as a "pattern" and have a guy cut out as many as you need. When all the rafters are nailed in, you can measure out from the building 1' 4" or whatever your plans say and mark the rafter on each end of the roof. Snap a line. Now, even if the wall is not perfectly straight, your rafter tails and fascia will be.
Also, if the roof is going to have "ridge vent," the ridge beam will be lowered a little to allow air flow. You will need to account for that on the top of the rafter after you make your 9-12 cut and before you mark for the bird mouth.
Thanks for your reply. The VelociRafter series was created to teach how to use math to solve some common roof framing questions, especially for complex roofs. I personally found that by preparing my cut list prior to picking up my saw, I could dramatically reduce the amount of time it would take me to frame a roof. If your approach works for you, thanks great! Another idea for allowing venting at the ridge is to hold back the plywood an inch or so from the ridge vent.
Wow this is a great video. I will have to look at it several times in order to absorb all the info. Hope all this is on your website. I plan on looking at it because I plan on building a 24' x 24' storage barn with a gambrel roof. Thanks, very helpful
Explain how the cut of the bridsmouth doesn't affect the end angle cuts? If you look at your drawings and make the ridge cut and building line cut then make the birdsmouth cut , you change the angle of the end cuts.
I believe what you referred to as a ridge beam is actually a ridge board ie only aligning the rafters and not bearing weight.
R&R Homestead yes, he makes reference to a ridge beam and the plan call what looks like a ridge board a ridge beam. But no big deal, he’s not talking about the the difference each makes in roof dynamics. The rafters are cut and stacked the same and this vid is meant to show us the math involved. Which I can appreciate, but I know what you mean.
Classy video :)