Guys or gals , on a 14 foot wide room that has octagon end but not all sides are even , are the hip rafters still 12/13 pitch when of course the common rafters are 12/12 pitch? I know that on an even three sides wall that the hips are a #/13 pitch. Any help would be great , save me some time and money working on it!
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The hips are not 12/13 because with the three sides different it's not a true Octagon with the hips running at 67.5°.
You said the building is 14' wide. What are the three side dimensions and what is the overhang? If you want the overhang to be the same all the way around, the hips will sit off the corner.
Maguire,
What are the side measurements and the front wall measurement, and also the overhang?
Any roof, irregular Hip, octagonal, whatever ...
Hip Run = Common Rafter Run ÷ sin Plan Angle
Hip rafter slope will be Rise / Hip Run
Enter the Main pitch, Adjoining pitch and corner angle measured between the eaves in plan view:Framing and Joinery Angle Calculator
Once you know the angles (angles being ratios modeling the roof on any scale) you can apply trigonometry to determine the dimensions of the roof components.
These next two links should help you with the dimensioning. Circumscribe the octogon with an ellipse:Ellipse Axes given two points on the Ellipse
Now that you have both working points and the ellipse axes in plan view and a rise:
Elliptical Roof Calculator Joe Bartok
Have you considered publishing in a book format? I think you'd be well recieved in the various trades libraries of " GO TO" books.
At least you would in mine.
Incredible work and concise explanations are rare.Spheramid Enterprises Architectural Woodworks
"If you want something you've never had, do something you've never done"
"Have you considered publishing in a book format? I think you'd be well recieved in the various trades libraries of " GO TO" books.
At least you would in mine.
Incredible work and concise explanations are rare."
Off topic:
Sphere, yes, I have given a "how-to" book some thought but five years ago I (belatedly) discovered the Internet ...
My original intention was to acquire a proper domain name, create a presentable website with a forum, Google Ad-Sense, etc. Having spent some time on the 'net I've decided this isn't worth the effort. (Site-forum maintenance, a constant struggle with hackers and malware ... who wants to bother with that ####?).
I have also considered producing a tutorial CD. Something interactive where the user can click on an image of a log-timber-stick framed roof and extract-rotate the geometric components, display the trigonometric ratios. Explanations of how to combine these ratios to create formulas and apply them ...
Some of my Internet research has devolved about finding a program suitable for this effort. Java? Vrml? ... now there is SketchUp ... Suffice to say that while I can handle the theoretical math I face a steep learning curve in applying it.
But as luck would have it ... last year a lady moved across the street from me. She wrote (or was involved in writing) the tech manual for a 3D program called Maya. The company she was employed with (I believe it was called Alias ... gone mams up in the dot bomb) was involved in the animations for the Terminator movies, Discovery channel's Walking with Prehistoric Beasts. So it looks like I might be able to get some tech assistance - maybe. I'm told what I have in mind is pretty much a team effort, a monumental effort at that. When producing an animation it's not unusual for one person to spend a day working on a hair ...
I am again giving a book some serious thought, it's seems like the best way to go. Know any publishers interested in producing a framing and joinery theory manual?
Joe Bartok
Edited 9/1/2007 12:00 pm ET by JoeBartok
Taunton or Rhodale Press ougtta snap it up. I'd contact both, and let em fight over ya!Spheramid Enterprises Architectural Woodworks
"If you want something you've never had, do something you've never done"
As usual I'm running out of Internet time for the day. I don't know what your equal overhangs are but this will affect working point for the calculations. So here is an example solution ... unadjusted values (no allowance for the overhangs), measurements in feet:
½ Octagon Width = Common Run = Rise = 7
Ocatgon Side minus Clipped Corner = 7 – 2.5 = 4.5
Plan Angle = arctan (7 ÷ 4.5) = 57.26477°
Hip Run = 7 ÷ sin 57.26477° = 8.32166 ***
Plan Angle for Corner Triangle = 135° – 57.26477° = 77.73523°
Corner Common Run = 8.32166 × sin 77.73523° = 8.13173 ... this is the altitude of the triangle in the corner
Hip Pitch Angle = arctan (7 ÷ 8.32166) = 40.06982°
Hip Rafter Pitch = 12 × (7 ÷ 8.32166) = 10.09414 ... about 10 1/8 over 12
Corner Common Rafter Pitch Angle = arctan (7 ÷ 8.13173) = 40.72271°
Corner Common Rafter Pitch = 12 × (7 ÷ 8.13173) = 10.32991 ... a hair greater than 10 5/16 over 12
These Triangle Solvers will help you check the lengths of the sides of the triangles.
For example the remaining angle in the corner triangle is 180° – (2 × 77.73523°) = 24.52954°. Enter this angle and the two 8.32166 sides in the "Known: Two Sides, Included Angle" calculator ... the remaining shortest side of this traingle is 3.53553. (We don't really need Javascript to solve this ... trigonometry or the Pythagorean Theorem will work fine).
*** the Hip runs are the radii of a circle. The entries for the Elliptical Roof Calculator would be:
Major Axis = Minor Axis = 2 × 8.32166 = 16.64332
Rise = 7
X1 = 7
X2 = 4.5
There is a link to diagrams showing what the calculator angles and lengths mean.
Joe Bartok
Edited 9/1/2007 2:12 pm ET by JoeBartok
Joe
It would sure help clean my desk up if you could put all of it in one book.Over the years, I've printed many of your replies, and save them as reference.
I appreciate the effort you put into these forums.Thanks
Greg from Connecticut
Hey , Joe Thanks also , The run is 7 feet 1/2 of 14 and the pitch is 12/12 , and like I wrote to Framer the corners are clipped 2' 6" across front and 2' 6" from front going in on sides Any Calculation help if you are good at it which obviously you are would be much appreciated but I will try it myself with your links ! Thanks Steve
Edited 9/1/2007 12:12 pm ET by maguire
Maguire,If you tell me the length of the overhang, I can give you the angle the hips run in plan view and how much off the corner they will sit on the front 9' wall. The plan view angles that Joe gave you are for the hips sitting on the center of outside corners of the top plate. When you add the equal overhangs to that the hips will sit off the corners and the plan view angles change according to what size overhang you have.Joe Carola
Edited 9/3/2007 11:22 pm ET by Framer
Yes I know what you are talking about framer , I really want the hips to line up with the corners especially on the inside because its going to be cathedral and I want it to look straight with the corner but id like soffits to be even also . I might have to scab onto hip tails to get nailing thanks again for your input and knowledge
What size is your overhang?If you want equal overhangs and the hips to sit over the center of the inside corner of the top plates for a cathedral ceiling, you will have to offset the hip off the corner and fur out the inside of the rafters to the center of the plate.The pitch of the small side wall plates will be different also.What size is your overhang? I'm only asking you again because I've asked you twice already and you haven't told me yet.....;-) You need the overhang length to figure this out.Joe Carola
joe lets say 1x8 soffits so after plywood with frieze bd. and possible bed molding would allow me to go about 8" 1/2
thanks, maguire
Maguire,With an 8-1/2" equal overhangs past the outside of the top plate, your hips runs at 58.12° on the front 9' wall 12/12 pitch section, with the same 7' common run as the two commons for the 14' span.The two side walls since they're stepped in 2'6 from front to back and in from the sides gives both side walls a 3'6-7/16" measurement. That makes your hips run at 76.88°.When you add the 8-1/2" overhang length to the common runs, that gives you exact points where your hips sit off the corners. It's always easier and more accurate to figure the overhangs in with the runs in plan view.Adding the 8-1/2" overhang all the way around makes your front wall width 115.0416", dividing that in half gives you 57.52082" or 4'9-1/2" for the run in plan view and 7' 8-1/2" for the rise in plan view and the Hip run 108.9261" in plan view running at 58.12°.Your side wall widths at 49.46804" dividing that in half, gives you 24.73402" or 2' 3/4" for the run in plan view, using the Hip run of 108.9261" as the Diagonal in plan view, giving you a rise of 106.0807" in plan view with the hip on that side running at 76.88°.Since the 12/12 front wall side has a run of 7'8", that means the rise is 7'8". Use that rise and the side wall 106.0807" as the Common Run, that makes the side wall pitch 10-7/16".To get the hip offset from the center of the 9' wall as you will see in the drawing, just use the 58.12° as the pitch. Then use 7' as the Rise, and your run is 4' 4-1/4". Measure 4' 4-1/4" in from the center of the 9' wall over towards the corner and that's your hip offset.Hope the drawing helps.Joe Carola
Framer nice work !! Do you use a construction calc. or a architectural software to do this drawing! I assume the 10 7/16 pitch is 10 7/16 /12 pitch . And This picture is more for an angle layout than rafter layout per say cause these measurements would be for ceiling joist lay out . In an even 3 sided octagon , all the rafters would have been 12/12 same as my common rafters but now only my 9' 7 1/16 area or front area are 12 /12 , what pitch are my hips at ? again normally on an equal 3 they would be a 12/13 pitch! really appreciate your help framer !!!
Edited 9/5/2007 10:39 pm ET by maguire
>> And This picture is more for an angle layout than rafter layout per say cause these measurements would be for ceiling joist lay out -->-->Maguire,The drawing is the plan view angle which gives you all your runs for the common, side, commons and hip runs including your equal overhangs. The plan view angles will help you visualize and solve all your triangles for any roof because it gives you the run. You already know that your rise is 7'8-1/2" because your 12/12 pitch main commons have a 7' 8-1/2" run.Now that you have your rise starting from the overhang and the top of the plumbcut at your fascia line, you just use the plan view runs we have for the hip and the side wall commons.I use a Construction Master Trig for everything. I get my numbers from that calculator and I draw them in the FREE Sketchup program that I have downloaded.((12/12 Main Common Rafter))12 [Inch] [Pitch]7 [Feet] 8 [Inch] 1 [/] 2 [Run][Rise] Returns- 7' 8-1/2"[Diag] Returns - 10'10-13/16" (Common Rafter Length)((10-7/16/12 Side Common Rafter)) 106.0807 [Inch] [Run]7 [Feet] 8 [Inch] 1 [/] 2 [Rise][Pitch] Returns - 10.46373" or 10-7/16" (Pitch over /12)[Pitch] Returns- 41.09° (Side Common Plumbcut Angle)[Diag] Returns - 11' 8-3/4" (Side Wall Common Rafter Length)((Hip Rafter))108.9261 [Inch] [Run]7 [Feet] 8 [Inch] 1 [/] 2 [Rise][Pitch] Returns - 10.1904" or 10-3/16" (Pitch over /12)[Pitch] Returns- 40.34° (Hip Pitch Plumbcut Angle)[Diag] Returns - 11' 10-7/8" (Hip Length)In this next drawing, you will see how the run for the Main Common, Side Wall Common and run for the Hip Rafter all tie into each other using the same rise to get your pitch and create a simple triangle.Joe Carola
Edited 9/6/2007 12:29 am ET by Framer
Once again you have shown what a valuable poster you are here. The effort and drawings you post here are above and beyond what alot of us can do.
I have learned more than I can ever repay from you, TIm Uhler, Diesel pig and Kirkpatrick. Vaults, bays and roof framing in general. All of it has become alot easier reading your guys' posts.
Thanks.
Matt
Matt,Thank You for what you said. I appreciate that. I'm glad I can contribute something to you and anyone else on the forum. It's a great place to be. I just think drawings along with explanations keep it simple and help so it's not so confusing.Joe Carola
THe drawings help out alot. I can easily get lost in the math, but with a picture I can look back and forth until I figure it out.
Thanks again.
Matt
Framer ,I am extremely impressed with first of all your knowledge and ability to explain it all with the plan but most of all the time and effort you have put into helping me figure this out ! I am very ,very grateful for your help ! I have been in and out of breaktime for a couple of years now but not consistently and have given alot of advice myself as well as received different ideas and advice ,but you take the prize !! Your knowledge shines through! Are you currently stiil working as a builder , framer? I have done plenty of octagon roofs , octagon ends etc but all even three sides .. Mainly We get a ton of common roofs ,Gables hips etc, you throw in a little twist and you have to go back to the drawing board. I know that I would have figured this out but not after alot of time and effort not to mention wasted wood ,so I thank you very much and tip my hat with the utmost respect!! The day we don't learn something new is the day we should hang up the belt, my belt can stay on another day because of you! Thanks Maguire
Edited 9/6/2007 10:19 pm ET by maguire
Maguire,I don't even know how to respond to all the things you said to me but, I Thank You very much. All I can say is that I love what I do, and I'm still Framing and love every minute of it. I guess I'm nuts. I enjoy these conversations and enjoy drawing because it does help you visualize and put the pieces of the puzzle togeher in roof framing. It also helps you realize in plan view how when you draw a triangle to figure the run and angle the hip is running at how it relates to the rafter Run, Rise and Hypotenuse.It also helps you if you want to learn how to use the Construction Master Calculator and how to learn to use Trigonometry. The easiest way for me to figure these roofs are always including the overhang, because that gives you your exact run to the top of the end of the rafter at the top of the fascia cut to the rise at the ridge.From there you can figure everything including your hip offsets and all your HAP cuts from that point to the plate line.Let me know how it works for you. I'm glad I could help.Joe Carola
Joe no response necessary , I too enjoy the conversation It is a joy to see when people know what they are doing! I,ve told many other builders about breaktime and tell them that its like walking into a room with many many builders and asking your question and knowing that someone will have your answer ready for you ! I am not the type of person to blow my own horn but I am proud of my reputation in the area that I live and I always have work because of it but I know that my skills are from natural ability of being mechanical like having an ear for music etc., but mostly a main part of my success is that I am not too proud or cocky to ask how to do something if I am not clear on something or if its not something we do a lot of ! The fact is ,is that no matter how good you are , there is always someone out there better and that is what should keep us striving to improve our workmanship! On a lighter note, Hows New jersey , Hot one out here today in Marshfield Mass . Not a good day to wear a dark shirt , I keep doing that and die all day ! Anyway Joe thanks again and I will definitely look you up again ! Do you work alone , have a crew, ? I choose to work only with one other guy ,assistant ,like to do everything myself . Got to loose that habit! Its killing me!! Talk to you soon , Steve . I have a Mac comp. and you can do your own site with a dot mac account . I ve got to work out a few bugs but check it out and let me know what you think ! If you've been reading finehomebuilding for a while you will recognize the ducks woven in the shingles which I loved when I saw it in one of there issues , The deer with a coyote sneaking up behind it was my attempt at an original! Site is http://web.mac.com/salcustom/
Looked at your website,great work.
I want too know on the tapered columns on the pergola are those built or are they solid columns cut to shape?
ANDYSZ2WHY DO I HAVE TO EXPLAIN TO FRIENDS AND FAMILY THAT BEING A SOLE PROPRIETOR IS A REAL JOB?
REMODELER/PUNCHOUT SPECIALIST
Hey Andy ,Thanks alot ! The tapered colomns are solid , Those are the only thing I had done at the guy who supplies the stock ,he has a big portable mill saw and He did that by blocking up one end the same amount he wanted to taper! The decorative cuts on the end of the beams were cut by putting beam level on sawhorses and having band saw on wheels . Move the saw and not the stock.
Hey framer thanks for the picture , If you picture the addition at 14 feet square and then clipped the corners at a measurement of 2' 6" in across the front from each corner and the same distance in on sides from the corner which still give me 45 degree corners but not equal three sides , Basically just like your picture ! An even three sides would be 12/13 hips but obviously not now! and yes even soffit and fascia all the way around! Any help is very much appreciated!!