Bastard Roof?

 
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Old 06-15-2007, 07:17 PM   #1
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Bastard Roof?


I've read this a few times and I'm not exactly sure what you're all talking about.

I searched the question and there wasn't anything specific....Is it when you build an addition that lays over an existing roof?
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Old 06-15-2007, 07:35 PM   #2
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Re: Bastard Roof?


Bastard hip would be 2 different pitches comming together at the hip. Probably the the same at the Valley. Out here we call them a "Son of a _itch"...

I guess the definition could also be a hip or valley not at 45 degrees.


Last edited by K2; 06-15-2007 at 07:52 PM.
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Old 06-15-2007, 07:41 PM   #3
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Re: Bastard Roof?


Up until the 70's carps said that you couldn't put two different pitches together. I think a couple of guys really screwed up one day and to fix it they found out it could be done. Then the Architects were smoking a doober and thought it looked really cool. The rest was history.

Sometimes we call them a MF.
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Old 06-15-2007, 08:04 PM   #4
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Re: Bastard Roof?


And this is how you figure out the pitch of the bastard hip/val. Say you have a 6/12 and a 9/12. Minus 6 from 9 you get 3 divide that in half add 1.5 to 6 you get 7.5 which is your hip/val rise/plumb cut.
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Old 06-15-2007, 08:10 PM   #5
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Re: Bastard Roof?


Thanks...I didn't realize there was a universal term I could use! I think bastard is putting lightly!....I can't wait 'till the next time I'm in that situation just so I can say bastard as many times as possible and get away with it!...it doesn't stop me now, but it'll be fun
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Old 06-15-2007, 08:12 PM   #6
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Re: Bastard Roof?


Quote:
Originally Posted by JustaFramer View Post
And this is how you figure out the pitch of the bastard hip/val. Say you have a 6/12 and a 9/12. Minus 6 from 9 you get 3 divide that in half add 1.5 to 6 you get 7.5 which is your hip/val rise/plumb cut.
Is the run 12 or 17 Will? On a 45 hip the run would be 17 yes??
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Old 06-15-2007, 08:13 PM   #7
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Re: Bastard Roof?


Quote:
Originally Posted by JustaFramer View Post
And this is how you figure out the pitch of the bastard hip/val. Say you have a 6/12 and a 9/12. Minus 6 from 9 you get 3 divide that in half add 1.5 to 6 you get 7.5 which is your hip/val rise/plumb cut.
Splitting the difference between 2 numbers gives the same result as averaging. Would it be any easier to say 6 + 9 = 15, divide that by 2 to get 7.5?
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Old 06-15-2007, 08:46 PM   #8
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Re: Bastard Roof?


Quote:
Originally Posted by JustaFramer View Post
And this is how you figure out the pitch of the bastard hip/val. Say you have a 6/12 and a 9/12. Minus 6 from 9 you get 3 divide that in half add 1.5 to 6 you get 7.5 which is your hip/val rise/plumb cut.
Just to make sure I'm on the right page...6/12 meets 12/12 my hip/val plumb cut= 9/12 or approx. 37 degrees?
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Old 06-15-2007, 08:58 PM   #9
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Re: Bastard Roof?


Quote:
Originally Posted by WNYcarpenter View Post
Just to make sure I'm on the right page...6/12 meets 12/12 my hip/val plumb cut= 9/12 or approx. 37 degrees?
I don't think so because if you had a 4/12 4/12 hip roof your hip rafter would be 4/17. correct??
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Old 06-15-2007, 09:31 PM   #10
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Re: Bastard Roof?


deleted my inaccurate post.

Last edited by Kent Whitten; 06-16-2007 at 11:56 AM.
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Old 06-15-2007, 09:59 PM   #11
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Re: Bastard Roof?


Yes it would be a x/17 hip/val cut.

Second Look after looking at that equation it is faster and easier. I like that. I was explaining the way it was explained to me by a old framer.
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Old 06-15-2007, 10:02 PM   #12
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Re: Bastard Roof?


Quote:
Originally Posted by K2eoj View Post
I don't think so because if you had a 4/12 4/12 hip roof your hip rafter would be 4/17. correct??
My input sucks here 'cause I frame one roof a year and I do it the dummy way. Some of this roof framing lingo goes way over my head. I went and got my square, and set at 4 for the hip/val = 18 degrees...that's for a true valley at 45 degrees. With different pitches you're changing the slope of the valley?

Please correct me if I'm wrong....Throw in a bastard roof and the valley rafter splits the difference between pitches, ending with the top of one or both sections of rafters being either below or above the valley rafter continuosly.
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Old 06-15-2007, 10:19 PM   #13
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Re: Bastard Roof?


When you use a speed square you don't really think in terms of run..

Let me explain in terms that no one will understand.

The run on one common is 12. Take the 12 inch from your other common and make a triangle back to the hip. No you have a triangle with 12, 12 and an unknown. There was a dinasaur named Pythagasurus that came up with.. a sqared +b sq = c sq. So 144 +144=288. Square root of 288 =16.97. So that is the run of the hip. Change the angle of the hip but the 12 and the 12 are constants so 16.97 or 17 is a constant. But I don't think you can see it on a speed square.
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Old 06-15-2007, 10:23 PM   #14
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Re: Bastard Roof?


I should fix that.

12 squared +12 squared =288 then take the square root of 288=16.97.
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Old 06-15-2007, 10:34 PM   #15
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Re: Bastard Roof?


[

Quote:
Please correct me if I'm wrong....Throw in a bastard roof and the valley rafter splits the difference between pitches, ending with the top of one or both sections of rafters being either below or above the valley rafter continuosly.
[/QUOTE]
Wrong. You'll have one side with longer plumb cuts but the tops all meet the same as normal.
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Old 06-15-2007, 11:34 PM   #16
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Re: Bastard Roof?


Quote:
Originally Posted by JustaFramer View Post
And this is how you figure out the pitch of the bastard hip/val. Say you have a 6/12 and a 9/12. Minus 6 from 9 you get 3 divide that in half add 1.5 to 6 you get 7.5 which is your hip/val rise/plumb cut.
Justin,

That doesn't work.

If you have a 6/12 and 9/12 Bastard Hip combination, the hip plumbcut angle will be 22.59 or 5 over 12 on the framing square or 7-1/16 over 17 on the framing square.

If you did what your saying on a 6/12 and 12/12 combination, the hip plumbcut angle will be 24.09 or 5-3/8 over 12 on the framing square or 7-5/8 over 17 on the framing square.

The way your saying the hip pitch would be 9 over 17 on the framing square.

12-6 = 6/2 = 3 + 6 = 9/17 (That's way off)

If you want to frame a bastard hip, close enough isn't good enough. You can get every angle you want to the exact degrees and they will help you with everything on the roof.

A 6/12 and 9/12 Bastard Hip combo gives you 56.31 in plan view on the 6/12 side and that would be the saw setting when you cut the plumbcut for the jack rafters. You will have 33.69 on the 9/12 side in plan view and that would be the saw setting on the 9/12 side.


A 6/12 and 12/12 combo would give you a 63.43 in plan view on the 6/12 side and 26.57 on the 12/12 side.
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Old 06-15-2007, 11:38 PM   #17
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Re: Bastard Roof?


Quote:
Originally Posted by K2eoj View Post
I should fix that.

12 squared +12 squared =288 then take the square root of 288=16.97.
To figure out any diagonal for a square all you need to do is multiply the run by the square root of 2.

12x Square Root of 2 = 16.97056"

If you have a 14'x14' deck and want the diagonal you just multiply 14' in inches X the Square Root of 2.

168 x SR of 2 = 237-9/16" (Diagonal)
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Old 06-16-2007, 07:08 AM   #18
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Re: Bastard Roof?


Joe, Simplifying formulas is nice when the numbers are simple but then when they get slightly more complicated guys don't know what to do. Your formula works for 14x14 but doesn't work for 14x13.

They simplify the framing square to the speed square and the numbers work fine but the guys never step off a rafter or know that the hip is x/17.
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Old 06-16-2007, 08:10 AM   #19
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Re: Bastard Roof?


Quote:
Originally Posted by K2eoj View Post
Joe, Simplifying formulas is nice when the numbers are simple but then when they get slightly more complicated guys don't know what to do.
That's when they should learn how and what to do. This is what you do for a living so if any roof comes up and someone finds it difficult they should buy a book, come to a forum like this or do what it takes to understand the math or your framing square.

Quote:
Your formula works for 14x14 but doesn't work for 14x13.
That's why I said it works for a square. 14x13 isn't a square. There are many ways to figure a hypotenuse. It has to be up to the whatever someone feels comfortable with.

Quote:
They simplify the framing square to the speed square and the numbers work fine but the guys never step off a rafter or know that the hip is x/17.
Stepping off rafters is a waste of time. Even when I stepped off rafter, I never stepped off a hip. I can't understand how a framer doesn't know why the hip running at 45 is 17" for the run. Are you talking about a guy who just started framing?
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Last edited by Joe Carola; 06-16-2007 at 08:15 AM.
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Old 06-16-2007, 08:22 AM   #20
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Re: Bastard Roof?


The OP said he maybe did 1 roof a year.

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