Any journeymen carpenters/framers here?

[BHD]

If you want the peak an exact figure, above the wall, then one will have to calculate the depth of the birds mouth into the calculation, as when one cuts that out the rafter will drop that much, (not sure if that is what you were describing or not)

one way I was taught was to mark a center line on the rafter and use that to measure from, (now I almost always cut the birds mouth in 1 1/2" deep,

but if your having problems take a chalk box/line, snap out the lengths and heights on a drive way or floor, full size, and lay a board on the full size drawing and mark flip to other side of roof drawing, to see if it is correct and if it is mark pattern on it and copy it until you have enough rafters cut,

 

[pretendfarmer]

Yeah, the birdsmouth cuts throw off the fit at the ridge. Man, this is silly. With those numbers I gave, there should be an exact way to do this considering a full seat with a 4" birdsmouth cut, right? With all of the numbers I gave, my total rafter length is 7'2" without the overhang. I have triple and quadruple checked that, and come up with the same number every time. Now I just used the 7.25/12 calculation tim gave (not sure where he came up with it but I assume it's right?), cut a 4" birdsmouth and the rafter does not fit. It's too high on the ridge with the birdsmouth flush to the siding. Man, I cannot believe this is kicking my rear end like this.

 

[pretendfarmer]

My head is starting to hurt. I was just using the rafter calculator and it is saying I can't do a 4" birdsmouth because it's more than a third. I'm not sure where my math is off, but I am darn sure of the building size. I have measured it ten times. It is 47 9/16" from the top plate to the top of the ridge (I called it 47 1/2 because it's a proud half). The ridge is 1 1/2" wide 2x8 fir. The building is 145 1/8" wide. I am at a loss as to wtf is the problem with my math. I used a[SUP]2[/SUP]+b[SUP]2[/SUP]=c[SUP]2[/SUP] and subtracting 3/4" for half the thickness of the ridge I come up with a total rafter length of 7'2". I have failed somewhere.

 

[pretendfarmer]

Just thought I'd report that I used that nifty rafter calculator link, and based it on a 7/12 pitch with a 3'11 17/32" rise from top plate to ridge top. I cut everything at exactly the specs given. It was still too tall on the ridge, like the plumb seat cut was too far out. I decided to just go the hack carpenter route in the interest of time and lumber (I wasted a couple 2x6's), cut a 7/12 pitch, scribed where it hit the wall, made an approx 2 3/8" seat cut and they now fit great. I really don't know why I was never able to get a perfectly precise fit based upon just numbers. Oh well.

 

[BuilderML]

When locating your ridge you should be cutting your 2 rafters and then setting your ridge by sliding up inbetween your rafters. That sets it at the perfect height. Yes you could set it on post but don't nail the ridge to the post final so you can lift or drop it a hair if you need to. You have to remember that the calculator will get you dead on in a perfect world with perfect lumber. Sorry to say the lumber is not very nice now days. So adjustments may need to be made alittle for things to fit nice and tight. With that said glad to hear you got it to work. Also before cutting your rafter you could of taken a measurement from the edge of the ridge to the back of your seat cut to see if your were close.

 

[pretendfarmer]

My ridge may be sagging in the middle, but I will jack it up later if need be. What I am doing is cutting all my rafters and nailing them flush with top of the ridge. I've run them wild off the top plate of both walls and have not nailed them. Once I have all the rafters hanging off the ridge I will verify that it is level all the way across, then I will then start nailing off the birdsmouth cuts on the plate. This is probably a weird way to do things, but I'm not a carpenter by trade. I know plumb, level, and square, though, and my stuff always turns out nice. I will post some pics of my project as it goes along.

 

[BuilderML]

My ridge may be sagging in the middle, but I will jack it up later if need be. What I am doing is cutting all my rafters and nailing them flush with top of the ridge. I've run them wild off the top plate of both walls and have not nailed them. Once I have all the rafters hanging off the ridge I will verify that it is level all the way across, then I will then start nailing off the birdsmouth cuts on the plate. This is probably a weird way to do things, but I'm not a carpenter by trade. I know plumb, level, and square, though, and my stuff always turns out nice. I will post some pics of my project as it goes along.

You should be doing just the opposite. Make sure your walls are straight. And braced well. Nail your birdsmouth tight against the exterior sheathing or top plate depending how you did it and let your rafter rest against the ridge. You'll be able to adjust the ridge side to side and up and down by making your rafters even with the top of the ridge. I would do every fourth one this way and once everything is lined up you can go back a fill in the rest. Have fun with your project.

In regards to your previous post. I am just double checking something here. When you figure your rafter length you take your building width( 145 1/8") Minus the thickness of the ridge ( 1 1/2).. You said 3/4" just wondering if that may be it.

 

[pretendfarmer]

I see why that way is better, but my ridge is already nailed at the ends because it was heavy and long and I'm by myself. I would have to tear the nails out to be able to move it. I figured if I got all the rafters perfectly flush at the ridge, I wouldn't need to monkey around with it later. I will check that my walls are square as I nail off at the top plate. I sheathed them and squared them on the ground, and they are perfect. I'm probably going to add some Simpson ties to both the ridge connections as well as the top plate.

 

[BuilderML]

I see why that way is better, but my ridge is already nailed at the ends because it was heavy and long and I'm by myself. I would have to tear the nails out to be able to move it. I figured if I got all the rafters perfectly flush at the ridge, I wouldn't need to monkey around with it later. I will check that my walls are square as I nail off at the top plate. I sheathed them and squared them on the ground, and they are perfect. I'm probably going to add some Simpson ties to both the ridge connections as well as the top plate.

The biggest thing is making sure your walls are straight. You can eye up the wall or run a chalk line from one end to the other. If your two walls are parallel to each other everything should line up nice.

 

[pretendfarmer]

My walls are perfectly straight. I built them on the ground, sheathed them, then raised them, plumbed them, and anchored them. I'm not super happy with my rafters. There are a few that have small gaps between the birdsmouth and the outer wall. We're talking 1/8 inch or so, but still. I like things tight. I'm actually disappointed in my whole rafter calculation debacle. I feel like I failed and then just winged it, even though it's certainly acceptable. I've seen worse from builders, but I was excited to do the math and have everything be right, and it wasn't. I'm going to post some pics tonight.