Replies

1. 
   Guest_ | Jun 30, 1999 07:38am | #1

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   If it's just a straightforward hip roof, any basic carpentry text oughta get you through. If moneys an issue, Reed's "Residential Carpentry" is usually easy to find in used book stores because it's been used as a text book in so many vocational training program. I like it because it assumes you're a completely inept 19 yr old and lays things out in an assigned lesson. If it covers something you havent seen or done before, its usually a good starting point though basic. If moneys really an issue, get thee to the library. A standard hip roof is only intimidating the first time. If its one of those weirdo bastard kinda hip roofs, be specific and some of the better roof framers around here can start getting you really confused.

   JonC

   P.S. Once the light comes on around the concept of "common difference" its all downhill.

1. 
   Guest_ | Jul 01, 1999 04:45am | #2

   *Phil:Here's 3 words: "Roof Framers Bible". This book is a field reference for actually doing the framing. If the info you seek is more theoretical, probably the book JonC recommends is better. Here's a little tip on a basic concept: For a regular hip roof (all the same slope) the slope of the hip rafter is x in 17, where x is the first number in the common rafter slope. In other words, for a 8:12 hip roof, the hip rafter has a 8:17 slope. Not sure what the significance of the 17 is - that's just the way I learned it. It's always 17. Somebody correct me if I'm wrong on this.

1. 
   Guest_ | Jul 01, 1999 06:47am | #3

   *Fred:That's interesting. Let me put that in my calculator and triangulate it for a few minutes.thanks

1. 
   Guest_ | Jul 01, 1999 06:52am | #4

   *Good call for the "Roof Framers Bible". By the way, the diagonal of a 12"x12" square or the hypotenuse of a right triangle with 12" sides (rise and run) is 16.97" rounded to 17" That's why you use it for hips and valleys.

1. 
   Guest_ | Jul 01, 1999 06:53am | #5

   *phil,Do you have a specific roof in mind that you are currently about to frame, or are you just interested in general knowledge of the subject?If you have a specific example, let us know about the floor plan and the plate heights and you should get some good help from your friends here at Breaktime

2. 
   Guest_ | Jul 06, 1999 07:39pm | #6

   *Fred,You're almost right. The number 17 is indeed the number used in cutting hip and valley rafters. This is because all american framing pitches are expressed in terms or 2in 12, 6 in 12 etc. The rise in a 6/12 pitch is 6 feet for every 12 feet. The rise in a hip is also 6 feet, but the run is not 12 feet. The run is always a diagonal line going to the corner of the building. If the building is 24 feet wide, the last common rafter will be 12 feet back from the corner. Therefore, the hip run will be A squared plus B squared = C squared where C is the hip rafter (or hypotansnooze). So 12 squared plus 12 squared (or 2 times 12 squared) equals the hip rafter squared. The square root of this equals the hip rafter run and this is always 16.97056 or 17.Clampman

3. 
   Guest_ | Jul 07, 1999 05:02am | #7

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   You guy's might be missing the point and Fred's hungin to much with Von Bozo. The "ism' that your missing is the ism-that states that the hypothenuse of any isosceles right triangle is equal to one of it's side multiplied by a factor of 1.4142, which by chance is the square root of 2.

   Since regular hips are projects of the hypothenuse formed by the run of their roof, the equation of (run * 1.4142) will always produces the theoretical length of this hypothenuse. Also, since 12 is used as a basis to calculate pitch, multiplying it by 1.4142 will produce ~ 17. This will work for any value used providing it comes from a square. This doesn't work for irregular hips.

   Joseph Fusco View Image

4. 
   Guest_ | Jul 08, 1999 03:08am | #8

   *Fred,I should have done your math before opening my mouth. The sq. root of 2 is a new one on me, but it obviously works. I just did the proof using the pythagorean theorem (A sq + B sq = C sq is the same as the sq root of 2 times A= C when A=B). Since my brain cells took a big hit in the '60's, about all the math I can remember is the pythag theorem and the trig functions. So I generally reduce all the problems I can down to where I can work with them.I apologise Fred, keep up the good work. Just remember, pie arent square, cornbread are square; pie are round.Regards,Clampman

2. 
   Ricks_ | Jul 08, 1999 06:16am | #9

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   Hi
   I also logged on to pick the brains of anyone who knows " The proper way" to do a truss hip roof.
   I have stick framed plenty and rolled trusses plenty. But I am never 100% sure about the blocking or short rafters runing up to the ridge beyond the hip girder that all the common jacks are atached to . Also what about where the hip jacks are instaled . I am real careful with my layout . and I always seem to have a problem geting the hip jacks to line up on the hip rafter just right . Any insight would be appreciated.

1. 
   Brian_Harding | Jul 18, 1999 08:30pm | #10

   *I've written my own book on Hip roofsas well as many other aspects of framing so if you'd like some quick and simple ways of laying out hips or precutting your jack rafters before the roof even begins to develop write me at [email protected] I cover many things in my book as well as bastard hip lines

1. 
   Bryan_Revor | Jul 19, 1999 11:34pm | #11

   *Hi Matt,If I'm not mastaken 17 is the dagional measurment of a square that is 12" by 12". Since hips run at a 45 degree angle 17 is always the run on a hip rafter.Good luck

3. 
   Guest_ | Jul 23, 1999 07:19pm | #12

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   The 1-1-sqrt(2) triangle is just one of the "right triangle" shortcuts they teach in geometry class; sq(a) + sq(b) = sq(c) is still king. Of course, what's the fun in having the hip the same slope as the main roof. Architects are trained to avoid boring builders with such things.

   Other popular shortcut triangles are the 3-4-5 triangle (dating from ancient Egypt I think) and the 1-2-sqrt(3) (also known as the 30-60-90°). Others?

   Isn't this about when someone pipes up to say you should use those mysterious tables on the framing square?

4. 
   SuperCarps | Jul 25, 1999 09:32am | #13

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   Mercy! Is it possible this guy only wanted help with layout? If so, choices abound. Typically we find center and lay out both directions on the wall perpendicular to the ridge. Then we layout sidewalls so that jack rafters align on hip rafter. Many things can negate this, including bastard (switch pitch) roofs and stack framing. It's a matter of preference and code as to what will work here.

   SuperCarps

   P.S. I put off buying a "construction master" calculator for two years, fussing with all that math. It paid off the first day. The tiny, plain english booklet taught me things I might never have learned otherwise.

5. 
   phil_peterson | Jul 25, 1999 09:32am | #14

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   looking for any info on hip roof framing
   layout...