I have a three sided building (addition) that is 26’2″ with a 5/12 going out 20’0″ to an 8/12 and although I am able to make the overhangs line up and the hips work due to drawing everything out on plywood to get my heel heights, I dont know the magic or the formula and I dont think I’ll sleep well until I get it.
Thanks,
Dustin
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Replies
as they say in the orient: rotsa ruck
"I needed a drink, I needed a lot of life insurance, I needed a vacation, I needed a home in the country. What I had was a coat, a hat and a gun."
Raymond Chandler's Philip Marlowe
Huck,In your drawing, if his building is the way you drew it and you use 13'1" as the 8/12 pitch run, you rafter length would be, 15' 8-11/16" and the rise would be 8' 8-11/16".That would make the 20' run pitch 5.25/12 and not 5/12 and the rafter length 21' 9-13/16".If they wanted the pitch to be 5/12, the run would have to be 20' 11-3/16".If you went the other way and used the 20' run first using a 5/12 pitch, your rise would be, 8'4" and then the pitch for the 13'1" run would be 7-5/8/12.Also with an overhang, the hip would sit off the corner.Joe Carola
The ratio of the 5/12 side run to the 8/12 side run is 1.6 ... and this assumes the angle in the corner is 90°.
If the 5/12 side run is 20' (240") and the 8/12 side run is 13'-1" (157") as per the drawing, the ratio of the runs is 1.52866 ... so the pitches can't both be correct.
And is it possible the "three sided addition" is trapezoidal and the angles at the corners are not 90 degrees?
Joe Bartok
Edited 5/22/2007 2:49 pm ET by JoeBartok
Edited 5/22/2007 3:03 pm ET by JoeBartok
Edited 5/22/2007 3:04 pm ET by JoeBartok
Huck, In your drawing, if his building is the way you drew it and you use 13'1" as the 8/12 pitch run, you rafter length would be, 15' 8-11/16" and the rise would be 8' 8-11/16". That would make the 20' run pitch 5.25/12 and not 5/12 and the rafter length 21' 9-13/16". If they wanted the pitch to be 5/12, the run would have to be 20' 11-3/16". If you went the other way and used the 20' run first using a 5/12 pitch, your rise would be, 8'4" and then the pitch for the 13'1" run would be 7-5/8/12. Also with an overhang, the hip would sit off the corner.
I didn't have enough info on the overhang to draw it. I used the dimensions he gave for the addition - and drew the existing structure with the pitch he specified. Meaning I assume he has no control over the actual rise. While he called the addition 5:12, it isn't exactly - I know that. But it would be typical of an archie to spec it that way, and let us work it out in the field.
Like you, I'm wondering if my drawing is even close to what he's actually doing. I just threw that out there to open the dialogue and try to give us a reference point to make adjustments from until we can figure out for sure what he's building."I needed a drink, I needed a lot of life insurance, I needed a vacation, I needed a home in the country. What I had was a coat, a hat and a gun."
Raymond Chandler's Philip Marlowe
i think "a roof cutters secrets" by will holladay might be better that 'Roof framers bible".
bolanger, I will agree with you , couldn't remember that name at the time.
I don't own a copy of it though have just leafed through a friends copy.
"Poor is not the person who has too little, but the person who craves more."...Seneca
Fine Homebuilding is certanly a top quality publication, but I am amazed that so many Breaktime responders are learned philosophers!
sarison,
Just what is it you are looking for ?
I don't understand what magic or formula you want. you must have a good understanding of the problem if you can draw it out.
I would suggest you try to locate a small book : "The Roof Framers Bible". I use it and it has all the formulas and "Magic" within it.
There are a number of great books people here use, I am sure others will weigh in with their favorites.
"Poor is not the person who has too little, but the person who craves more."...Seneca
Edited 5/22/2007 3:11 am by dovetail97128
We need to know about your overhangs.
There is no magic formula. If you want the overhangs to be the same distance out from the house wall, the hips won't be on the corner of the top plate--they will need to be offset.
So you managed to scale it down on a sheet of plywood and make it all fit? Bravo! Excellent carpentry! And now you can't sleep because the higher math is bugging you? Don't let it. You solved the problem through simple, applied geometry. The next time something of this kind turns up, you'll enjoy the process that much more, using your own skill and experience to make things fit.
Leave the higher math for the engineers and other academics. They occupy the buildings that we've constructed, under roofs we've provided for them, never knowing the great inner connection that comes from taking two dimensional drawings and turning them into human structures.
There are moments in life which are worth savoring because they have the quality of the infinite. Making inner connections between mudane tasks and real human needs provide opportunities for such moments. Those who follow their inner life find those moments more often than those who focus on one aspect of a task.
Edited 5/22/2007 7:15 am ET by Hudson Valley Carpenter
Leave the higher math for the engineers and other academics.
I disagree. I think Joe Carola or Dieselpig could probably do that work with their calcs (or simply in their heads because the've done it enough times) and come up with the right "math" to do the job. I dont frame so without putting some effort into it and then still looking like a rank amature among some pretty good framers I'm not going to attempt it. I do know the math side of it though so if need be I could probably figure it out.
I work with a pretty good carpenter that always makes fun of me cause I will use the math to do some simple stuff like finding a radius. He thinks his simple way of bending a thin piece of wood and drawing around it is good enough, and sometimes it is but if your building a radiused soffit above a radiused bar that method aint going to cut it, not if you want it to look good!
I think knowing how the math end of it works will help you better understand the complexity of the problem.
Doug
I dont frame
So you get your satisfaction from doing the math. That's fine but that's your end of it and that's where it ends for you. Please don't make the supposition, as many engineers and architects do, that we tradesmen need you or your math in order to enjoy our work. Although we respect what you contribute to the building process, we don't need to burden our brains with academic knowledge.
Frankly, I chose carpentry because it liberated me from that world. So don't presume that I'd be better off if I forced myself to see my work from your limited perspective.
It's an excercise in futility to debate which branch of math is more valid or useful. The formulas for solving a complex roof using trigonometry (or vector analysis, or calculus, or whatever ...) are dictated by the geometry of the roof. You can get the correct answer using only a compass and straightedge, or (more quickly and accurately as far as I'm concerned) with a calculator or a computer.
Valley Soffit Overhang Adjustment ... an example of the so called "higher math". The principle to offset a Hip rafter is the same.
The "custom" offset calculation was used to position this Valley: Valley Rafter intersects Beam
There is another offset calculation to determine the "Hip drop" if your Hip rafters are not backed.
Joe Bartok
Edited 5/22/2007 8:12 am ET by JoeBartok
Edited 5/22/2007 8:14 am ET by JoeBartok
"I dont know the magic or the formula and I dont think I'll sleep well until I get it."
I think he must have drifted off...
"Please don't make the supposition, as many engineers and architects do, that we tradesmen need you or your math in order to enjoy our work."
You know, don't you, that Doug U is a fellow carpenter, right? And a darned good one? What's your beef?
Your rant calls to mind the Bolshevik Revolution. Workers of the world, unite!
And if it weren't for those engineers, you would still have to paddle your little canoe across the Hudson, instead of doing that Rip Van Winkle bridge, or the Tappan Zee, the GWB, the Verrazano Narrows, or the tunnels, or whatever.
You know, don't you, that Doug U is a fellow carpenter, right? And a darned good one? What's your beef?
How would I know that? Not by what he wrote in his post, which disclaims knowledge of carpentry, or in his profile, which reads "Scientific/Research" under occupation.
So what's your beef? Looks like you're the one on a rant. I'm simply defending the freedom to pursue a craft on it's own creative merits.
Edited 5/22/2007 9:57 am ET by Hudson Valley Carpenter
"How would I know that?"Well, for one, you've been here for at least a year and a half now. (Member since 11/21/2005)Doug is no shrinking lily.Given the number of posts Doug has made here, it would be pretty much impossible not to have read anything else he has ever written here. It would also be pretty much impossible not to have already figured out that he is a pretty good carpenter.Unless, that is, you simply ignore anything that does not directly relate to you and/or your own posts. Or maybe more to the point, anything that does not directly stroke you and/or your own ego.Now, if that is the case, more power to you. You undoubtedly limit the time you spend here, by doing so. As well as keeping yourself out of certain complications that can arise.However, when a consequence such as this one arises from those browsing habits, you should not be surprised. Nor do you have room to be 'righteously indignant' when you are called on making a post that illustrates your complete ignorance regarding your fellow posters.
Fight fire with water.
Well, for one, you've been here for at least a year and a half now. (Member since 11/21/2005)
True, but I haven't been reading this board all that time. It's only in the last two months, since I began designing a new spec house and wanted to learn more about new materials, that I returned to this board and began asking questions and posting on other topics.
There are a lot of people posting here, hundreds, many with similar names. After two months, an hour or so each day, there are only a few who I recognize readily.
By the way...
He doesn't frame.
Just exactly HOW does that translate into "which disclaims knowledge of carpentry,"
Here's the full quote: "I dont frame so without putting some effort into it and then still looking like a rank amature among some pretty good framers I'm not going to attempt it."
That sounds like he's disclaiming the required knowledge to me. Understand, I didn't write that as criticism. I just made an observation in order to clarify my position for another poster.
One big problem with writing for message boards is how to state a personal opinion clearly without alienating anyone. T'ain't gonna happen, not as far as I can see.
I respect everyone who posts here. I've recently stated, in another thread, that I learn something new here on BT, almost every day. I believe that's evidence of respect.
"One big problem with writing for message boards is how to state a personal opinion clearly without alienating anyone. T'ain't gonna happen, not as far as I can see."Too true.Peace.
Fight fire with water.
By the way...He doesn't frame.Just exactly HOW does that translate into "which disclaims knowledge of carpentry,"
Fight fire with water.
Some trades just know they're above the rest.
Many moons ago, when I wuz involved in the heavy industrial side of things, it seemed to me that the pipefitters figured they were the top roosters. That was industrial work, union stuff, jobs with 50 to 100 fitters on board, all wearing those little Landry hats from Texas under their hard brims.
In the residential trades, it seems to be the frame carps. Like, "If you ain't a framer, you ain't sh*t."
I can understand why. They are the ones that get to move in after the mud and dirt trades have wrapped up, work fast, loud, defy gravity, slap up the structure, stick a little tree on top. Amaze themselves with a little compound geometry, make a ton of sawdust. Turn that foundation with its big hole in the middle into a real building, by God!
Use terms like bastard hip, hooked on, snappin' it out.
Framing's my favorite part of housebuilding. Too bad it's over so quick.
Now, if we can get this OP's hip figured for him, we'd be all set.
Hudson
How would I know that? Not by what he wrote in his post, which disclaims knowledge of carpentry, or in his profile, which reads "Scientific/Research" under occupation.
You're not supposed to know what I do for a living but to assume that I'm an engineer/architect is certainly a big leap on the assumption scale!
I made a statement regarding my framing, or lack of framing skills because I haven't spent a lot of time in that particular area of carpentry. I've framed simple houses for Habitat, 38' X 26' rectangles with simple 4/12 truses and I do just fine but no way am I going to do some of the complex frames of the houses that I work in. I'm in awe of those guys that do that. These new multi-pitched, multi-dormered, multi-hiped and valley'd houses are as foreign to me as the Chinese language.
That's fine but that's your end of it and that's where it ends for you.
No that's not where it ends for me. I went to college for mathematics and computer science so yea, I understand the math part of some of this stuff, I also understand why math is vital to what I and a whole lot of other guys on this forum do for a living. I understand that the "understanding" of math is also vital.
Off the top of my head I cant give you the simple formula for finding the area of a circle but because I have a fairly decent understanding of mathematics I can come up with it, along with the circumference, how to find the radius with out any known variables and a whole host of other useless information.
BTW, this is what I worked on for the last week. These are my shots from today.
Disregard whats in my profile, I change it weekly, next week I'm going into entertainment!
Doug
Nope. You obviously don't know anything about carpentry :P
Disregard whats in my profile, I change it weekly, next week I'm going into entertainment!
There's another point of view, often expressed on this board, that posters should provide accurate and useful information in their profiles. If you want to be taken seriously on serious topics, that's one way to make it happen.
Maybe the quote I took from your post was false modesty on your part. If so, it was misleading, just like your profile.
I'm not responsible for your statements nor did I misinterpret them. I took them at face value. If you're unhappy with what I wrote in response to the inaccurate information that you provided, there's your remedy for future exchanges.
Hudson
There's another point of view, often expressed on this board, that posters should provide accurate and useful information in their profiles
You know your probably right but I don't take a lot of stuff all that seriously, certainly not myself, I'm not saving any lives here! I know the guys that know their stuff on here so it doesn't matter to me what a profile says.
I couldn't tell you what Piffin, Joe Carola, Dieselpig, .............and a whole lot of other guys profiles say but I know that they know what there talking about. Hell Mike Smith didnt have anything in his profile the last time I looked so whats that mean? Brownbagg always has some b.s. in his profile but I know that he knows concrete. That might not be of any help to a new guy but damn man, you shouldn't be using any information you get from the net without checking it out first.
Maybe the quote I took from your post was false modesty on your part.
Come on, nobody would say that I'm modest!
Really I don't know squat........ or a whole lot about framing, sure I know studs go 16" on center, what cripples, kings, headers..........are, but that doesn't make me a framer. And yea, I could frame a simple house but I wouldn't want to tackle anything to difficult, I'd rather do what I do best and have somebody else do it for me that way I'd know it was done right.
I'm not responsible for your statements nor did I misinterpret them.
Your right, your not responsible for my statements but it's entirely possible that you misinterpreted what I was saying, or maybe more likely, I didn't articulate it well, something I'm often guilty of.
I'm not worried about whether or not you take me seriously, like I said, I'm not saving lives here, I come here to have some fun, exchange ideas, rag on people, same as when I go to work.
My only problem that I had with your original post was that I disagreed on whether or not you(anybody) should have a better understanding of math. Just my opinion, you obviously disagree and that's cool, if your way works for you then that's all that matters.
Math isn't just for geeks! :)
Doug
I'm not responsible for your statements nor did I misinterpret them.
Your right, your not responsible for my statements but it's entirely possible that you misinterpreted what I was saying, or maybe more likely, I didn't articulate it well, something I'm often guilty of.
And you're right too. I didn't articulate my thought very well there. I should've said "nor did I intentionally misinterpret them."
It's likely that I didn't fully understand your intention. That's going to happen a lot, when people who've never met try to expound... one on his personal philosophy (me) vs. another's interest in a more scientific point of view (you).
Philosophy and science are like oil and water, even without the language interpretation problems or the lack of personal contact. Add to that my old rebellion against formal education and my personal philosophy gets muted while I do my Don Quixote imitation, arguing with anyone who esposes a position which supports academic learning.
Peace brother, Peter
Peter
Add to that my old rebellion against formal education
Oh I rebelled plenty against formal education myself but I didnt go to college until I was 30 years old so for me it was just a place to aquire some knowledge - no brain washing took place!
Later
Doug
>next week I'm going into entertainment!<
For me sometimes non-profit or charity is the better choice.
Your sawdust is quite impressive. Nice!
Whoooooooweeeeeeeeeeeee! 'Nuff said Dougie! Your work speaks for itself brother. That sh1t is gorgeous! Dude, I don't even wade into most of the discussions about the math behind the framing. Framed plenty of bastard hips but the truth is I have a hard enough time explaining it to my guys on site, never mind walking someone through it over the internet! Wish I could.... I'm just not that telented. Never met a roof I couldn't frame... met plenty I couldn't explain though!
View ImageView Image
Looks like a bar in the basement, right?
Imagine it in your place, Brian. Look at the pic again, imagine the circular ceiling area over the back bar, the part that is all trimmed out with the curved drop with walnut frieze, the circle part dropped down a little, backlit from above, and a big stained glass RED SOX logo there.
Nice, huh?
Yeah, I could deal with that for sure Gene. That's walnut huh? Everytime I see rich dark work like that it blows my doors off. I could eat it.View Image
Gene
Its cherry!
And that damn thing has to be done tomarrow night. It is a bar in a basement, lower level for those that dont like to think of something like this in a basement.
I'm waiting for the media room to get completly outfitted, its right next to the bar and probably the most complex thing I've ever built, pictures to follow!
Doug
pictures to follow
Looking forward to them.
wow 50 some posts........ and no one said or suggested marrying her, no bastard hips anymore, youns are slipping.
not to change the subject but anybody into the canadian show........trailer park boys?
Dan
Edited 5/24/2007 7:11 pm ET by danz857
Never met a roof I couldn't frame... met plenty I couldn't explain though!
I'm guessing you know more about the math involved in those roofs then you realize!
I enjoy reading all the posts that Bartok put out there, I understand all of it but I cant convey any of it to others, I dont have the ability to teach - to articulate the message, you might have the same problem. when I'm trying to show someone something I get frustrated, I expect others to read my mind!
Doug
Never met a roof I couldn't frame... met plenty I couldn't explain though!
I've framed my fair share of Bastard hips and couldn't explain it or give a formula.
I learned a long time ago that you can get pretty far with a few blocks of 2X10, a string line and a sheet of plywood to draw on and a basic understanding of triangles.
The guy who taught me how to cut roofs called it the "Fisher Price Method"
"You're not supposed to know what I do for a living but to assume that I'm an engineer/architect is certainly a big leap on the assumption scale!"
not to mention the severity of the insult he threw at U by saying yer a stinking engineer and /or architect!
only worse thing I could thing of would be calling U a "designer" ....
Jeff Buck Construction
Artistry In Carpentry
Pittsburgh Pa
only worse thing I could thing of would be calling U a "designer" ....
Not so! I could've called him an interior decorator. ;-)
But I wasn't trying to insult him, just making my case for simplicity.
" I could've called him an interior decorator. ;-) "
same dif ... that's the chick I had in mind!
Jeff Buck Construction
Artistry In Carpentry
Pittsburgh Pa
not to mention the severity of the insult he threw at U by saying yer a stinking engineer and /or architect!
Yea, no shid!
Thank God that I've mellowed in my later years!
Doug
You know, don't you, that Doug U is a fellow carpenter, right? And a darned good one? What's your beef?
How would I know that? Not by what he wrote in his post, which disclaims knowledge of carpentry, or in his profile, which reads "Scientific/Research" under occupation.
How would you know that? You have nearly 500 posts here -- don't some of the names start to look a little familiar after a while?
Doug is a homemaker for crying out loud. Cut him some slack.
:P
<<How would you know that? You have nearly 500 posts here -- don't some of the names start to look a little familiar after a while? >>
Actually no. I had a concussion, swinging above a concrete floor then losing my grip and falling, when I was nine. It has effected my memory ever since. I'm particularly bad at remembering written facts. Names of people I'm introduced to slip away almost immediately. I only remember a name after I've been around someone long enough to appreciate them as a real person.
On this board, I only remember the names of some people who use an icon or a company logo as part of each post. Right now, I'd be hard pressed to tell you more than five names on this board, maybe not that many.
When I read the title of this thread, I thought someone was complaining about my arse again. Naturally I came in here to set them straight.Imagine my horror when I open it up to find out it's really about *shudder* MATH !!
Fight fire with water.
Very well put.
Daveth_mz_09_10009883884-1
With a Construction Master, there really isn't any need for "higher math".
If I can figure out the roof, then anyone can and it doesn't take long either.
The math isn't really all that high. If a guy can read a framing square he can get by doing most roofs. If he can get a grasp on Pythagoreon Theorem even better! Combine that with a little knowledge about similar trianlges and they can really accomplish wonders.
Have a good day
Cliffy
I agree that there are simpler methods. That was my initial point, in encouraging the OP to enjoy his own creative on-site, in-the-moment method of solving the problem, without feeling the need to see it as "higher math".
By those same simple means, a little plain geometry and a framing square, the carpenters of my generation and before have made our way through every peculiar roof and stairway we've ever encountered, plus any number of problems, unforseen-by-archys/engineers, which seem to crop up daily on custom homes and commercial buildings.
It's my experience that there's more satisfaction...pure fun...to be had by keeping it simple and personal. There are other potential benefits as well, for anyone who will pause and savor the moments of connection in all their fullness.
Peace and spiritual prosperity,
Peter
Edited 5/23/2007 1:08 pm ET by Hudson Valley Carpenter
ALL: The math isn't difficult. The way I see it, it's not good enough to find a formula in a book or on the Internet and just start pushing buttons on a calculator. In order to apply the math I think it's important to understand where the formulas are coming from; this usually means getting a grip on the roof geometry.
EDIT: For anyone who is interested I just made a series of posts today on how to get from the geometry to the trigonometry and formulas (or, getting from compass and straightedge to calculator) in this Roof Math Thread
Thirty seven posts, counting this one, and we still can't answer the OP's question ... whatever the question was ... :)
Joe Bartok
Edited 5/23/2007 2:00 pm ET by JoeBartok
Edited 5/23/2007 2:00 pm ET by JoeBartok
Edited 5/23/2007 2:02 pm ET by JoeBartok
Edited 5/23/2007 2:02 pm ET by JoeBartok
Thirty seven posts, counting this one, and we still can't answer the OP's question ... whatever the question was ... :)
That's because the OP hasn't answered any of our questions yet.
Joe Carola
Looks like he read the responses so he knows we want more detail.Joe Bartok
"So you managed to scale it down on a sheet of plywood and make it all fit? Bravo! Excellent carpentry! And now you can't sleep because the higher math is bugging you? Don't let it. You solved the problem through simple, applied geometry. The next time something of this kind turns up, you'll enjoy the process that much more, using your own skill and experience to make things fit. Leave the higher math for the engineers and other academics. They occupy the buildings that we've constructed, under roofs we've provided for them, never knowing the great inner connection that comes from taking two dimensional drawings and turning them into human structures. There are moments in life which are worth savoring because they have the quality of the infinite. Making inner connections between mudane tasks and real human needs provide opportunities for such moments. Those who follow their inner life find those moments more often than those who focus on one aspect of a task."That was actually petty good. . .http://joes-stuff1960.blogspot.com/
Sarison,
Is your building like Huck's drawing. If so what is the overhangs?
Don't worry about the math because it's used every day in framing. Once you have a formula, you'll never forget it. Do you have a Construction Master Calculator?
not sure exactly what you are asking,
the plan view of the hip is pretty simple.... the ratio is 5 to 8
if it were a 4/12 with a 9/12 the ratio is 4/9 or 4 in 9
when both pitches are equal say 8/12 the ratio is 8/8 which is the same as 1/1 or 12/12 thats why the standard hip is a 45 degree angle.
is this what you were asking?
Check the archives. This has come up before.
Maybe roof overhang or some term like that might work in a search.