OK, all you construction master calculator pros! All you wizards of roofs! Here is the challenge.
Lay out the roof plan for a bastard hip, 8:12 shallow pitch, 12:12 steep, overhang on 8:12 side is 14-1/2″, on steep side it is 9-1/2″.
Forget the hip cutting for now. What we want to know, and see your sequence of CM key entrys and results, is how the hip is positioned on the plates.
Its centerline is not right over the corner. Where is it?
Edit: I forgot to give one more piece of important information. The hip is a single ply 2x member, thus 1-1/2″ thick.
Edited 3/16/2006 10:36 am ET by Gene_Davis
Replies
Gene - can I play even if I don't use a CM, and don't frame bastard hips? The overhang on the steep side would be 9 5/8" (9.66") with the hip centered on the outside corner, and the overhang on the 8:12 side being at 14 1/2". So specifying the overhang on the steep side at 9 1/2", you're pushing the hip back 1/8" toward the 8:12 side, from the corner. Why bother?
"he...never charged nothing for his preaching, and it was worth it, too" - Mark Twain
View Image
"he...never charged nothing for his preaching, and it was worth it, too" - Mark Twain
Gene - just a brief observation: I see that you edited to add the thickness of the framing member. Everyone does it different, but when I'm figuring a roof, I use centerlines, and don't worry about the thickness of the material. Later, when cutting, I compensate for the material size. Sometimes it makes things more confusing to put too much information into the initial calc's.
"he...never charged nothing for his preaching, and it was worth it, too" - Mark Twain
The Hip rafter is shifted .28846" toward the 8/12 side of the roof.
This same scenario was recently brought up in the JLC Forums.
Didn't use a CM to arrive at the answer, though. Sorry!
Hip/Valley Sections Calculator
Theory: Proportional Hip Shift/Drop
Joe Bartok
Edited 3/16/2006 1:09 pm ET by JoeBartok
Edited 3/16/2006 1:12 pm ET by JoeBartok
That's not what I get, Joe.
In plan view, I've got one edge of my 2x running over the plate on the 12-pitch side, and the other edge over the 8-pitch side. It is not centered, though.
My hip rafter is plain on top, not beveled.
It is a fun discussion, but over at JLC the guy that started the thread there didn't seem to be interested in how to get it right, so I brought the thread here, where the real pros congregate! ;-)
Maybe I'm not understanding the question? I'm showing the theoretical location of a Hip rafter, with or without backing, where the jacks plane in. The figure I gave would be as viewed or measured in section or the plan view from the corner of the eave.
1.03846" on the 8/12 side, .46154" on the 12/12 side. Splitting the difference gives .28846". The Hip drop would be .38402".
This is my web page version of the Hip Shift Math.
Ollee, who participates in this forum as well as JLC, submitted this drawing of a Geometric Method of Determining the Hip Shift.
I use this shift for backing log Valley rafters. This produces an equal amount of arc on each side of the Valley.
Joe Bartok
Edited 3/16/2006 2:04 pm ET by JoeBartok
Edited 3/16/2006 2:06 pm ET by JoeBartok
Edited 3/16/2006 2:10 pm ET by JoeBartok
I didn't do the math, Joe. I used 3D CAD to model the geometry, then let the CAD program give me the numbers.
The attached .pdf print shows the corner in plan view, of my model.
One important note, and it may make the difference between what I have here and what your math model does. I "forced" the overhangs at 14-1/2 and 9-1/2. Those were given by the mastermind OP over at the JLC forum. If you recall, his roof is trussed, and I believe the truss plant engineer's program works backwards from the overhangs.
Whatever, it doesn't matter. My model has those overhangs, and the hip rafter (or truss) tail must corner out on the overhangs.
My heelstands differ by some tiny number, I recall it being something small. Maybe your math model makes heelstands match, thus the difference between your results and mine.
Edited 3/16/2006 2:46 pm ET by Gene_Davis
Edited 3/16/2006 2:47 pm ET by Gene_Davis
I get it. The measurement I was giving would be the difference between the dashed and solid lines shown on your drawing. I didn't translate it into eave measurements. Nor have I considered the heel heights. I don't recall that there was any information given in that regard.
Yeah, it's too bad there isn't more feedback, follow-up and detail on a lot of the questions that are posted in forums. The guys don't mind putting an effort into finding a solution because someone else's problem could be their problem tomorrow or next week.
Gotta log off for the night. See you all tomorrow.
Joe Bartok
Edited 3/16/2006 4:00 pm ET by JoeBartok
OK, looking at your pdf drawing, and doing some head-scratching, this is what I see. The hip falls basically on the corner, with a tiny adjustment as spelled out on your drawing. The only reason for the tiny adjustment, that I could see, is that your overhangs require it.
In other words, if the overhang on the 8:12 side is 14.5", then the top of your fascia will be 9.67" lower than your H.A.P. at the outside edge of the wall. So if you make the overhang 9.67" on the 12:12 side, then the top of your fascia on that side will plane in with the top of your fascia on the 8:12 side. But you chose a very slightly different measurement for the overhang, requiring a slight offset in the hip. But its so close, why bother? Why not just make it 9.67"? That was my original question.
If you make your overhang 9.67" on the steep side, then the center of the hip should fall directly over the outside corner of the building. As long as the H.A.P. on your hip seat-cut is consistent with your common rafters at the point where it intersects the outside of the wall. Looking at a plan view of your hip, you will see that the H.A.P. on the steep side of the hip will differ from the H.A.P. on the shallower-pitch side of the hip. Hence, the seat-cuts on the steeper side will require a slightly different (higher) H.A.P. than the seat-cuts on the 8:12 side.
OK, OK, I think I see where we differ - All of my figuring presupposes a cut-and-stack situation, where you have the option to adjust your seat-cut depth. On the other hand, in a truss-roof situation, where the trusses can't be cut, there would be an adjustment of the hip off of the corner, to compensate for the differing pitches - so that the H.A.P. would end up consistent on both sides of the hip. A little basic calculator math tells me that would be .35", or 3/8", measured along the plate line."he...never charged nothing for his preaching, and it was worth it, too" - Mark Twain
Huck, you are right about not needing a CM. Plain old trig works for all this roof stuff, and I could probably do it with my slide rule.
Your diagram shows the roof plane intersect line (a.k.a. "hip line") traveling over the wallplates where they corner at 90, and missing that corner by a scant amount. No problemo there.
But hey, who bevels their hip tops anymore? Certainly not this hack! We want simply to have the 5/8 sheathing plane out on the edges of our hip rafter. For that reason, we need to know its thickness, in order to figure how it is placed.
So, a little more work is needed, eh?
Gene - I'm not sure I get you...the thickness of the framing member (hip) should not be a factor, IF the Height-Above-Plate measurement is consistent at the outside edge of the wall. Just figure where your hip will intersect the outside edge of the wall, and make sure your H.A.P. at that point is consistent with the H.A.P. of the common rafters. No need to bevel the top, it will plane in just fine."he...never charged nothing for his preaching, and it was worth it, too" - Mark Twain
Huck, stick with me on this. And go back and read the OP.
Note I say the o'hangs are fixed. Yep, fixed. Can't change 'em.
I said in a later post that the heelstands, which isn't quite, but in sort of a way, is H.A.P., are not the same on the steep-pitch and shallow-pitch sides.
But the heelstand on the hip member, on each side common to its adjacent rafters (or trusses) is exactly the same, as it must be for the roof to plane.
In my model with a 1-1/2" width hip rafter, its center is more or less 1/2" down the 8/12 line. If I make the hip rafter a doubled 2x, or 3" thickness, it's center moves, in order for its non-beveled top edges to plane.
As is said on "The Ali G Show," . . . "Check it out!"
An isometric view of my little 3D wireframe model is attached. See the heelstands?
They are different, and as projected onto the sides of the hip member, show us that to make a true seat cut, we would measure down a different HAP on each side.
Right, as I stated in my previous post (which you didn't see before your last post), when the hip is centered on the outside corner, the H.A.P. is different on each side. By sliding the hip 3/8" toward the shallower side, the H.A.P. becomes identical on each side of the hip. Thus, the overhang should be adjusted accordingly. Basically, 9.67" - .35", which is 9.32" or 9-5/16", would be the ideal overhang. The top of the fascia would plane in perfectly, and your sheathing would plane in to your hip.
But you can't change your overhang, it is carved in stone, so to speak. So you have a minor discrepancy that you have to live with. If you were into hair-splitting (which rough framing generally does not require), you would have to shim the top plate of the 12:12 wall by 3/16", since you can't adjust the hip placement to make it all plane in with identical wall heights.
Are we on the same page now?"he...never charged nothing for his preaching, and it was worth it, too" - Mark Twain
No, we are not quite on the same page, Huck, but we are close.
If this were a stickframed roof, you were my lead framer and I was your cutter, I would have it all cut and stacked before your last wall got raised, and your rafters would give you
a true 8/12 on the principal side
a true 12/12 on the secondary side
tails that would line so your subfascias meet up as expected
a 14.5 o'hang on the principal side
the specified 9.5 o'hang on the hipped ends
and one of the key aspects of marking and cutting would be to do the HAP on the principal side different than on the hip ends. Right is right, right?
I'd say, I didn't deal this mess, I'm only here to figure, then whack and stack.
There is absolutely no reason to have the HAPs equal. They certainly are not equal when equal overhangs are specified for an irregular hipped roof.
Furthermore, my 8:12 rafters would all be marked with a different template than those on the 12:12 end. And, why would I want my lead man to have to shim?
Here is your next roof geometry question. Sort of a pop quiz. Where do you place your hip member (let's make this a two-ply LVL at 3.5 width) so that the HAPs are equal along primary and hipped sides? This time, I'll say that the overhang on the 8:12 side is the same 12.5 inches, but that the o'hang on the 12-pitch side is up to you. Just be sure to make those heelstands match.
Sharpen your pencil, and begin, now! Tick. Tick. Tick. . . .
If this were a stickframed roof, you were my lead framer and I was your cutter, I would have it all cut and stacked before your last wall got raised
That would be quite a trick!
There is absolutely no reason to have the HAPs equal
That may be, but it doesn't mean they couldn't be. As I said, on a cut-and-stack roof, I would cut the roof with two different H.A.P.'s. If your truss mf'g. designed the roof with equal H.A.P.'s, then you would have to compensate by adjusting the location of the hip. Which is what your original post intimated. i.e. - having to shift the hip location just slightly, so your sheathing would plane in at the hip (something that wouldn't occur if you could adjust your H.A.P.'s while cutting your commons).
And, why would I want my lead man to have to shim?
With a cut-and-stack, you wouldn't need to - only with a truss roof, with the overhang dimension off by 3/16 (9-1/2" instead of 9-11/16"), would you have a need compensate somehow along the steep pitch side. If you didn't, then your trusses would be 3/16 low at the fascia, or 3/16" high at the plate. In actual practice, a difference of 3/16" would not even give pause to most framing crews. Close enough, nail it!"he...never charged nothing for his preaching, and it was worth it, too" - Mark Twain
Well, I hope I can find the time to catch up on all these posts! This seems like a good place to pursue this problem. That JLC thread seems to be on the verge of self-destructing.
Btw, I just realized this morning that I completely missed that pdf in the first JLC post. Heel height 9-1/4" on one side of the roof, and 10-3/4" on the other ... ???
And I don't get the 2" offset toward the steep side (Post #20, JLC thread), it doesn't fit with the dimensions given for the overhangs. Nor is the thickness of the Hip rafter given.
Joe Bartok
Edited 3/17/2006 11:12 am ET by JoeBartok
Edited 3/17/2006 11:13 am ET by JoeBartok
Edited 3/17/2006 11:17 am ET by JoeBartok
If you didn't, then your trusses would be 3/16 low at the fascia, or 3/16" high at the plate
With a trussed roof, we easily adjust the heels of the side hip package by shifting the entire hipset in or out to create the perfect heel height. We also have to adjust the projections too sometimes.
We cant shim a truss up 3/16 because the ceiling memebers would be out of level.
blue
We cant shim a truss up 3/16 because the ceiling memebers would be out of level.
Good point. Guess you can tell, like Tim, I'm a cut-and-stack man. Done a few truss roofs, not as many tho'. Adjusting the hip location was my solution of choice, but the OP wouldn't have it. I originally thought the question was posted by someone with a problem on a job. Then I find out this whole thing is just an exercise in theoreticals."he...never charged nothing for his preaching, and it was worth it, too" - Mark Twain
Gene,
You were kidding when you said "There is absolutely no reason to have HAPs eqaul" right? Because saying that would just mean you have no idea what you’re doing right?
Joe, lay out an irregular hipped roof for cutting, one that has equal overhangs on its primary pitch and secondary pitch sides. Then see how unequal those HAPs are.
In fact, take a look at the diagram attached to my earlier post in this thread, in which the HAPs are unequal, but close.
But hey, it's only trigonometry, and the numbers are what they are. A good roof cutter should be able to whack and stack to 1/16" precision, but it is up to the rest of the crew to deliver level, square, and linear plate accuracy, and then erect it all so that everyone is proud of the results.
Gene,
The last time I checked, I wacked a few roofs together. When was the last time you wacked one together? An 1/8" is certainly OK.
To state that the HAPS don’t need to equal is just a novice mistake.
In regards to split pitches a better understanding would be that the plane line heights always need to be the same and that any combination of plate rise and HAP cut that gets you there is all right.
Joe - I understand where you're coming from. HAP's would always remain consistent on a regular hip roof. But draw an irregular hip in plan form, centered on the corner, and look at where the edges intersect the outside edge of the wall. You'll notice that the points of intersection are not directly opposite each other. Hence, if an irregular hip is centered over the corner, then the H.A.P.'s are different, although only slightly. Which would be no big deal, the rafters would be cut with a different pattern anyway. And a steeper pitch has a wider vertical cross-section, making a slightly larger H.A.P. appropriate.
"he...never charged nothing for his preaching, and it was worth it, too" - Mark Twain
Edited 3/17/2006 9:53 am by Huck
Huck,You might be confusing the hip drop for split pitches with the HAP for split pitches. Since hip drops are different for all pitches most guys will either bevel both sides and maintain the same HAP. Drop the hip x amount and just bevel one side or just shift the hip so it planes in on both sides. http://www.josephfusco.com/Junk_Drawer/8-10shift_slide.gif
No, no confusion. You said what I said, you can shift the hip to make it plane in on both sides. I didn't discuss bevelling the hip, because the OP said he was trying to avoid that."he...never charged nothing for his preaching, and it was worth it, too" - Mark Twain
Huck,Not to be argumentative, but you did say “Hence, if an irregular hip is centered over the corner, then the H.A.P.'s are different, although only slightly.”;-)
Yup, and its true. Thus, you have to shift the hip if you want the HAP's to be the same on both sides."he...never charged nothing for his preaching, and it was worth it, too" - Mark Twain
Huck,Well then I’ll just have to disagree with you. . .Since the HAP is always measured from the top of the rafter down to the plate it would be quite impossible to have one member with two different measurements and have the roof plane in.;-)
With the irregular hip centered over the corner, the H.A.P., which occurs at the outside edge of the wall, is different on each side.
View Image
If the hip is shifted slightly off-center of the corner, the H.A.P. will be the same on each side of the hip.
View Image"he...never charged nothing for his preaching, and it was worth it, too" - Mark Twain
Huck,Well then I’ll just have to disagree with you. . . again. . .
OK, I'll try again. Here is the irregular, or bastard hip that I drew earlier:
View Image
Here it is, in 3-D. You can see that the H.A.P. is higher on the steep side, than on the other side. Kapish?
View Image
"he...never charged nothing for his preaching, and it was worth it, too" - Mark Twain
Edited 3/17/2006 8:58 pm by Huck
I get it. But I been gettin' it all along. Let's see what ol' roof-cutter-Joe says. He's the best!
It's like takin' a rocket ship to the moon. Just because I only done it once or twice, don't mean I can't do it again. Repetition don't make you smarter, just maybe quicker.
Now let's do some curves!
Gene,
Besides your computer program, how much stick framing have you done? I'm not asking to be rude, I'm just curious.
Hardly any, Tim!
But I enjoy it just the same, doing one once in a while. But I take it all the way from mudsills to staircases, curves and all. The geometry work-outs are fun!
I'm 62, and it's a second career for me.
Roof cutting and staircases are for me, the most challenging parts of housebuilding, because of the 3D aspects of it. But hey, it's mostly just trigonometry. And common sense.
Did you read Larry Haun's piece about framing in the 25th anniversary issue of FH? Talk about speed and efficiency! Larry was gang-cutting back 40 years ago.
Gene,
I thought I remembered you talking about building from the bottom up awhile ago, but I sometimes forget who says what :-)
62? You got it all figured out by now? I'm 28 and I think I'm going backwards sometimes. What would you call that? hmmm I'll come up with a term. That's our game on the jobsite. We try and make up almost believable sounding stories and seeing if anyone will bite.
Today Jasen asks Kyle while we are framing a CA valley (blind, over framing, etc) Do you know why they call it a sleeper board? Because the guy who invented it had narcalepsy (sp?) Our trim guy has that, so I'm not making fun, but it was pretty funny.
I did read Larry's article and I think that is the best article in FHB that I've ever read. Made me proud to be a framer and see the history. He was at the Portland JLC last Dec and I was about 5 ft from him. I should have gone up and met him, but I'm not the most gregarious guy. He seemed kind of shy too, but man that guy has framed!!
Huck,
I can’t see any of the pictures you posted but I doubt it would advance this discussion further. So, once again I’ll just disagree and move on.Gene,
The next time I’m going to the moon I’ll look you up.Blue,
Some things will never change and that’s a good thing.As a general note if you’ve framed any kind of roof where your HAPs are difference and you have not changed the plate height, in my opinion you’ve done it wrong.In this example where the overhang was dimensioned at 9-1/2" instead of ~9-5/8" could have been just the accuracy setting being set to a 1/4". Like I said before this 1/8" means nothing, my lumber tolerances alone can be off more then an 1/8". My saw blade wondering a bit could make up half of it in one pass as well. A fat pencil can also effect it too. You get the point.If it where me and it somehow bothered me instead of trying to move the hip off the corner and change HAP heights or raise plates (if I were so inclined), I would have just shorten up the 14-1/ 2" a bit. No one would ever have noticed. I believe the MAJOR problem with this roof was that they moved the hips in 2" off the corner.
As a general note if you’ve framed any kind of roof where your HAPs are difference and you have not changed the plate height, in my opinion you’ve done it wrong.
Joe, you obviously are misunderstanding something.
How could we be doing something wrong for 15-20 straight years?!!! I remember setting my first irregular hip packages using trusses in the mid eighties..maybe 86 or 87. They had different heels then and to this day I've never worked on an irregular with equal heels.
You guys obviously place some higher priority on getting that hip to line up over the rough corner but that doesn't factor into our thought process at all. Our exterior details are designed with equal overhangs (closed cornice) and simple math will dictate that if you have an equal overhang and unequal pitch, that the heels will be different if you are using trusses.
When we use trusses, it's impossible (not impossible but crazy) to change the plate heights. The bottom of the trusses are built on one level plane. If you raise a wall, the trusses would have to be raised and notches built in and then they would have to reframe underneath to bring thing level. If anyone insisted on doing something this crazy, the truss companies would refuse figuring we are whacked out. It makes no sense whatsoever to change the plate heights, when using trusses.
Of course, when we do our conventional framing, we use the same mentality. We keep our overhangs equal and adjust the heel height. I've built conventionall rafters with 36" heels!
blue
Blue,After reading that. . . I’m speechless. . . 36" HAPS wow. You got a picture of that?Take care. . . . . .
Yes Joe, I happen to have some pictures. Heres a couple of them.
blue
Blue,Nice pointy rafters, but I don't see any Birdsmouth cut? The HAP on thoses babies would be 0.Keep looking. . . .
Edited 3/18/2006 1:21 pm ET by Joe
Blue,Just in case you forget what the HAP was,
http://www.josephfusco.org/Articles/Roof_Cutting/roof1d.gif
Okay, I looked at Joe's picture. He's showing a heel of approximately 5". I'm showing you a rafter with a heel of about 36".
Do you need me to add some pointers to the picture to show you where the heel is?
blue
Blue,Yes, that would nice if you could add some pointers to show me where there is a 36" HAP.Thanks.
Hope this works.
blue
Blue, I have come to believe that there are actually those out there in the world of framing who have little or no experience with trusses. Your remarks are falling on a lot of deaf ears. It's as if you are speaking Greek.
Furthermore, these masters of the timbered arts have little or no regard for those who build or have built with trusses. We are as infidels, or barbarians, or worse. We're way beneath them.
It seems as if they are determined to get that hip right over the corner, bastard or not, and then fight to keep HAPs equal. Congress needs to pass an equal HAPs amendment!
Think of how it will please the timber interest constituents. More plates stacked up there means more jobs!
For those of you who are the true sultans of sawn lumber, I worked out the geometry as the problem was stated. Irregular, 8/12 principal, 12/12 secondary, 14-1/2" overhang along principal side, 9-1/2" across hipped end.
My rule was that the overhangs measure from stud line to outboard face of 2x6 subfascia, that the rafters and hip are cut for a flat box soffit, and that the hip is shifted into the corner to get bearing for roof sheathing without having to bevel the top.
Please, if you are so inclined, get out your CM calculators, or your trig tables, or framing squares, or whatever, and correct errors you find.
You can see in the details that the rafter tails are cut so that the sheathing can come down to kiss the outboard top corner of the subfascia, and that birdsmouths accommodate the sheathing. We sheathe the walls flat on the decks, but hey, that is just a regional preference.
Also note that stuffing the hip over into the 12/12 side, creates the need to whack its end plumb cut at 9 degrees.
To be absolutely precise, this hip should have a heavy 1/8" beveled off its 8/12 edge, but what the heck, we're lazy, and it's just framing.
That's why they call it rough.
Gene don't get so sassy now!
I don't see anything wrong with your math and the pictures seem to be perfect.
I myself have never layed out or calculated how far off the corner the hip lays. It lands where it lands! In the vast majority of cases, our hips fly right past the corner without touching them and I go back later and install a heel block.
I do one detail different than you. I plane the top of my sheathing so it touches the outside of the finished fascia board. This is a trick that I learned which speeds up the cornce construction in a big way. Not many people know or understand the significance.
blue
Gene - I'm confused. You said "these masters of the timbered arts have little or no regard for those who build or have built with trusses...It seems as if they are determined to get that hip right over the corner, bastard or not, and then fight to keep HAPs equal." But in the parameters for this particular roof, the overhangs given by you were what placed the hip over the corner. Like Blue said, with equal overhangs, the hip would fall far from the corner.
And as far as 'fighting to keep the HAP's equal', it was you who said "But the heelstand on the hip member, on each side common to its adjacent rafters (or trusses) is exactly the same, as it must be for the roof to plane." "he...never charged nothing for his preaching, and it was worth it, too" - Mark Twain
Huck, if you have seen the discussion of this roof over at the JLC forum, you will recall that the specs (pitches and overhangs) are part of a roof frame that was done in trusses.
The OP over at JLC was the one who fixed the overhangs where they are, which places the hip truss about, but not exactly centered, over the plate corners. His specs are from the truss provider.
The geometry that places a single-ply or ganged truss hip at an irregularly hipped roof is derived only from the two pitches, and the two overhangs. The completion of the truss geometry requires a spec for a minimum heelstand height. But even without a heelstand spec, we can determine hip placement.
Change the overhangs specs, and of course the hip, as it relates to the wallframe corner, moves. The easiest way for me to see that in 3D CAD is to model the walls and roof stuff on different levels, and just shift the walls under the roof.
My comment about working to create equal HAPs was directed at the framers who seem to think that this is a primary and must-do criteria. If you looked at the drawings in my stickframed solution, you see that the two sides don't share the same HAP dimension.
The remark of mine you quoted, "But the heelstand on the hip member, on each side common to its adjacent rafters (or trusses) is exactly the same, as it must be for the roof to plane," makes sense with careful reading of my less-than-precise prose. An irregular hip truss presents two different heelstands in the two directions it "sees." Those heelstands can differ, and they do in this example. But each of those two heelstands, one each side, must absolutely match the heelstands of the adjacent trusses. I recall that this example, for a single ply truss at the hip, has the heelstand figures almost 3/16" apart.
As a side note, timber and stick framing offer a little more flexibility in hip member placement, for an irregular pitch situation. This is because a timber hip can have its top beveled, either "pyramided," to have each beveled surface match the adjacent roof planes, or "shed beveled," to bring each edge into plane. Top-beveling, and how it is done, can cause a timbered hip to be moved to one side or the other of the hip plane junction of the roofs.
But bevel a hip truss? I don't think my truss provider likes me to cut them. Not at all.
In the example I did just this morning, of this hip done in stickframed components, note that the elevation of the rafter ends is different along each side, but that the roof plane comes to the subfascia edge. This is important to me, but maybe not to others.
Note also in my stickframe solution that the hip isn't centered under the roofplane break. My first solution trial, one with the hip end plumb cut at 90, had it even further to the left, with less bearing for the 12/12 sheathing, and more of a shed cut bevel required on the top. I "stuffed" it further over, to get closer to needing no top bevel to make the two arrises plane, and the further over it gets stuffed, the more the plumb cut at the end is skewed.
"...it would be quite impossible to have one member with two different measurements and have the roof plane in."
I'll have to agree with you. On a regular hip. But on an irregular, or bastard hip, its different."he...never charged nothing for his preaching, and it was worth it, too" - Mark Twain
Like this.
Joe, pay attention!
The heelstands on an irregular hipped roof can be equal, or different. It all relates to the overhang.
If I specify to you that I want 14.5" overhang on both the 8/12 and 12/12 sides, the heelstand on the steep line will be 4.833" taller than that along the 8/12 side. And of course, that hip won't come close to centering on the corner. It'll be way up the 12/12 line.
Here is the last one we did. Really. 6500 sf of roofed area, 54 different truss types, and I reviewed five submittals, trading 26 emails with the truss engineer, before I signed off on it for fabrication.
View Image
Edited 3/17/2006 9:07 am ET by Gene_Davis
Gene,I’m just going to circle around to my previous thoughts, you just don’t know what you are doing.The number 4.83 just defines the location of the “plane-in line” for the rafters and the hip. Guys who have some idea of what they are doing call this number the “plate rise”. You’d need to rise the plate this much on the 12 side and still keep the same hap to have the overhangs equal and have the roof plane-in correctly.This is just one number you’d need though. . . You still to know the hip offset, the ridge adjustment and depending on whether the raised plate is parallel or perpendicular with the main ridge what to rise it to keep the pitches correct.
Joe, you are too focused on maintaining equal heels and not seeing the forest for the trees.
Raising the plates on a truss job is not an easy or normal thing to do. It would add significant materials and labor and instead they simply adjust the size of the heel. We do this on every house we frame!
Every one!
blue
Gene,
I've been moving all week, so I just saw this thread and haven't really had time to read it through too closely, so bear with me . . . .
When you layout an irregular roof, it is much easier to keep the heelstands (HAP) the same. With unequal overhangs, the hip will center on the outside corner of the wall. Also, this means that you HAVE to bevel the steep side of the hip, OR slide the hip so that each edge planes with the pitch on that side.
IF you start from the hip, then you would have different heelstands (HAPS), but this is unnecessary.
Here are a couple pics of a 6-12 & 10-12 roof I cut a few months ago in the middle of our 27 days of rain http://pic9.picturetrail.com/VOL293/2163851/8885471/123448970.jpg
The garage was a 5-12 & 9-12 roof http://pic9.picturetrail.com/VOL293/2163851/8885471/124491908.jpg Everything was precut
On the hip for the 6-12 & 10-12 side, I layout the 6-12 side first and cut the birdsmouth http://pic9.picturetrail.com/VOL293/2163851/8885471/130655381.jpg Then flip the hip over and layout the 10-12 side. Using the same HAP, you can see that it's short of the top of the hip http://pic9.picturetrail.com/VOL293/2163851/8885471/130655380.jpg so that mark is the short point of the backing bevel http://pic9.picturetrail.com/VOL293/2163851/8885471/130656312.jpg Here it is nailed in place with the lowest jack http://pic9.picturetrail.com/VOL293/2163851/8885471/123448950.jpg
http://pic9.picturetrail.com/VOL293/2163851/9094915/128880996.jpg
When you layout an irregular roof, it is much easier to keep the heelstands (HAP) the same. With unequal overhangs, the hip will center on the outside corner of the wall
Tim, easier is a debatable term. I don't find it easier at all to build irregular roofs with equal heels. The only thing easier about that method is that I'd probably be able to remember the height of the heel without asking Frank ten times! LOL!
I find it fascinating that certain parts of the country feel it is necessary and aesthetically pleasing that the hip cross over the outside corner of the frame. It's fascinating to me because that idea never entered my mind until I read about it on this site. Around here, the emphasis is placed on equal sized projections and we all go to great lengths to make that detail uniform as much as possible. Because of that, I am confident that I have never, ever, ever placed a hip directly over the corner of a frame!
Never.
Ever.
Never!
And probably never will!
One perplexing question that I would have for you, if you ever moved to Michigan and built a couple of home like we do would be this: Where would the important corner be on a house that has brick front and Lapped Siding sides?!
Understand that I'm not saying anything you guys do is righter or wronger, but lets just say I don't think it's easier to do irregular roofs with equal heels. The time spent ripping the different soffit material would easily eat up the savings that I'd gain by being able to remember the heights of the heel, which is really the only advantage.
blue
Blue,
I've only framed equal overhangs once. Around here no one cares if the overhangs are unequal, so the hip passes through the corner.
If the room is vaulted, then the equal overhangs can look funny because you might have different wall heights on the inside where you can see it (assuming outside the soffits are closed). Even using different materials doesn't make up all the difference depending on the length of overhang and the pitches
I find it's much easier to frame unequal overhangs and it's easier to keep the heelstands the same. By easier, I mean there are fewer variables for me to keep track of.
Our goal has been to "idiot proof" as much of the framing as we can. So we try and simplify the process (whatever we are doing) each time we do it.
As to where the corner would be? I guess the GC would have to tell me and then I'd frame for it. :-) You mentioned brick, and that made me think, when was the last time brick went on one of our houses? I can't remember, but I think looking back, it's probably about 10 years ago. Stone partway up is the thing around here http://pic9.picturetrail.com/VOL293/2163851/4215098/130726748.jpg
By the way, did you ever email that guy about the platforms? We are looking at getting a bucket for our lift so we can scoop the scrap, ahem, the ah trash pile and put it in the dumpt truck :-)
As to where the corner would be? I guess the GC would have to tell me and then I'd frame for it. :-) You mentioned brick, and that made me think, when was the last time brick went on one of our houses? I can't remember, but I think looking back, it's probably about 10 years ago. Stone partway up is the thing around here http://pic9.picturetrail.com/VOL293/2163851/4215098/130726748.jpg
By the way, did you ever email that guy about the platforms? We are looking at getting a bucket for our lift so we can scoop the scrap, ahem, the ah trash pile and put it in the dumpt truck :-)
Ask the GC?! Hahahahahahahahahahahahahahaha!
AAAahahahahahahahahahahahahahaa!
That's funny.
I talked to the platform guy that day. They have a distributor here in Michigan. We can pick up a 10 platform for about $2200. We can't use 16's here in Michigan.
Since I don't intend to stay in the Carpentry business, I decided that I really don't want to invest any more money in something like that. I would have done it if I could legally use a 16.
We use our bucket a lot more than for just scooping scrap. Actually, we hardly every use the bucket for that, but occasionally we do. Or, maybe frank does use it for that and I'm just not around. I would own the jib before I'd own the bucket though but we do crazy things and it might not be a good choice for you.
blue
Gene is right. There is no reason why heel heights should match on all the walls of a house. I haven't worked on a house in twenty years that had all the same heel heights.
blue
0.167"
Can you read that on a ruler?[email protected]
It's Never Too Late To Become What You Might Have Been
Gene,
Reading this here and over at the JLC I really did want to stay out but. . . There are two major items wrong with the way that roof went together.
One, there should be no shift of the hip. Its center line should be right on the corner.
Two, all HAP cuts should be the same.
Lastly the 1/8" on the 12 side is just incidental, it makes no difference.
Yes! As a rule I shift the Hips/Valleys in proportion to the plan angles about the theoretical line that crosses the corner. That's what all that math in those links was about.
This isn't the only way: sometimes there are reasons why the Hip has to be shifted. But this calls for raising the plate and/or changing the heel heights.
See you all next week.
Why does everyone here make cutting and placing a Hip or Valley, Regular or Bastard sooooo difficult?
I don't think everyone does.
Why do the stick only roof cutters think they are so much better than the truss only guys? Or vice-versa?
Again - I don't see it that way, myself.
My framing background has many years of both cut and trussed roof constructions. I use the same math in the same ways on both types of roofs. I have framed more bastard roofs with unequal overhangs than with equal overhangs, trussed and cut. I position the hip at the corner of them all using the same formula.
With a truss roof, isn't it up to the truss designer to determine the location of the hip?
To keep things simple I always assume/make the HAPs equal.
Again, on a truss roof, isn't that the decision of the truss designer? While it generally makes sense on a hip or gable roof with a regular hip and equal pitch all the way around, and equal overhangs, I can't see how it should arbitrarily be applied to every roofing situation one might encounter.
To find the placement dims on a 1-1/2” Bastard Hip, 12 pitch / 8 pitch, using a CM Calculator enter 8” as a rise and 12” as a run, save the pitch, (8/12, in this example), enter 1-1/2” as the Hypotenuse, and then hit Run and Rise to get the leg dimensions of a right triangle in plan view for the bastard roof. These dims are where the equal height HAPs perpendicularly located on the correctly cut Bastard Hip will be placed.
Excellent! This is the same method I arrived at, but minus the CM, since I use a trig. calculator. It took a bit of head-scratching for me to arrive at that conclusion, but your brief explanation verifies my math. Definitely worth taking note of, if one encountered this situation frequently.
And I use the same effective run to calculate the Hip’s (or B-hip’s) length that I used to find the Common, or King Common.
This statement I didn't understand. The run of a hip cannot be the same as the run of a common rafter. This must work because the CM has the formula for converting common run to hip run already programmed into it?
I do use the hip placement dims to make effective run deductions for calculating the Jacks.
Could you clarify that? Sounds interesting.
"he...never charged nothing for his preaching, and it was worth it, too" - Mark Twain
Edited 3/18/2006 3:58 pm by Huck
Richard,
If I understood you correctly
To find the placement dims on a 1-1/2” Bastard Hip, 12 pitch / 8 pitch, using a CM Calculator enter 8” as a rise and 12” as a run, save the pitch, (8/12, in this example), enter 1-1/2” as the Hypotenuse, and then hit Run and Rise to get the leg dimensions of a right triangle in plan view for the bastard roof. These dims are where the equal height HAPs perpendicularly located on the correctly cut Bastard Hip will be placed.
Then that is what I do. This is an old picture, but I think the pitches were 6&10 http://pic9.picturetrail.com/VOL293/2163851/6234797/80052656.jpg It is similar to Huck's picture in an earlier post.
Using the CMTrig though I always use 8/12 inv tan for the practice or 12/8 inv tan
Tim,
I'm not sure offhand what an inverted tangent trig function does. If it finds the legs of a right triangle with a hypotenuse dim and a plan view ratio, then yes, you follow me. But your posted photo confusses me. I was talking about plan view dimension of the B-hip crossing the corner.
"To find the placement dims on a 1-1/2” Bastard Hip, 12 pitch / 8 pitch, using a CM Calculator enter 8” as a rise and 12” as a run, save the pitch, (8/12, in this example), enter 1-1/2” as the Hypotenuse, and then hit Run and Rise to get the leg dimensions of a right triangle in plan view for the bastard roof. These dims are where the equal height HAPs perpendicularly located on the correctly cut Bastard Hip will be placed.
Tim - I've been thinking about this, and the more I think about it the more I think its incorrect. At first glance it seems to be correct, because it works out with the example given, i.e. an 8:12 pitch and a 12:12 pitch. But the 12:12 pitch is unusual, because the rise and run are equal, creating a true 45 degree pitch.
But lets take the example of a 4:12 roof with an 8:12 hip. Let's say the run of the commons is 12, then the rise would be 4. The 8:12 hip would have a rise of 4 also, which would make the run of the hip common 6. In other words, 4:6 = 8:12.
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Thus, with a 4:12 roof and an 8:12 hip, you would enter 1-1/2" as the hypotenuse, but 6:12 as Rise:Run, in order for the above formula to work.
View Imageedited to add: OK, OK, I'm wrong here. 4:8 is the same as 6:12, whaddya know? False alarm!
"he...never charged nothing for his preaching, and it was worth it, too" - Mark Twain
Edited 3/19/2006 1:26 am by Huck
Huck, that little trig workout to yield hip placement, is what I use to place a hip truss, but I use the fascia lines to do the placement, like Blue does.
The two outboard corners of the truss tail, square cut across its end, are in position to plane to the subfascia boards.
So, my little triangle, with 1-1/2" as its hypotenuse, is seen out at the fascia corner, not the plate corner. I care more about what happens at the truss tail, than where it is placed on the wallplates. You can see that the offset dimensions differ at the facia corner, when compared to the wallplate corner.
My example is for the 8 and 12 pitch combo, with the overhangs (close to proportional, but not exact) of 14.5" and 9.5" respectively.
And, as I have been saying all along, the heelstands are different. The difference is 0.166, a little under 3/16".
Gene,You can attach the cad drawing to this forum just like any other file. Would you be so kind to attach yours so I can see just what you are doing?Thanks,PS. It dosen't matter what program created it. . . I'll be able to veiw it.
Try this, Joe. It is my .prt from Cadkey 97. And if that doesn't work, I will email it to you.
Tim, your pic shows the layout for the offset hip on the top of the hip itself. Problem with that is that the layout method Jalapeno mentioned only works in plan view (on a horizontal surface). Changing the layout to the sloped surface of the hip rafter will alter the angles.
View Image"he...never charged nothing for his preaching, and it was worth it, too" - Mark Twain
Huck,
If I showed all the pics, you'd see that we are talking about the same thing. I think that was a hip from Will Holladay's pic, so along the plate on the one side you'd measure perpendicular to the plumb line on the hip 1" and on the other side 5/8". On the block there, I just connected the dots to the center to show the angles.
Just like your drawing in a previous post, that shows that unlike a regular hip where you could measure back perpendicular 3/4" (if 2x) so that the HAP would show where the outsides of the hip touched the outsides of the wall, the irregular in my pic wouldn't be 3/4" on both sides, but the numbers it shows.
Edit:
I looked up your post and it's #38 The way I cut the hip though is that on the right hand side (steep side) of your 3D drawing, I'd measure the HAP from the seatcut that's been cut to the shallow side and then I'd back that edge. That way I can keep the HAPs the same and it's one less calc for me to deal with
Edited 3/19/2006 11:01 am ET by Timuhler
I also agree with him about those who say they don’t use equal HAPs to start their calculations. Those folks are either full of wind or just not explaining themselves well.
Welcome to the fray Mr Jalapeno!
Nice try on trying to restructure the debate, but that statement isn't anything I ever said.
For the record, if you want to know, all heels would start out at zero, if you want to do your calculation from there. With equal overhangs, you then assign one heel height to one set of rafters, then add the differnece to the other. It's very basic math....I think I could teach my kindergarden grandson to do it.
One thing that tickles me is that everyone here assumes that everyone starts all their calculation from the heel! That isn't necessarily true and I often do all my calculations from the fascia.
Why would I work from the fascia? Why not? It is the starting point of every common rafter and main hip in the roof isn't it? Quite often, the heel location is secondary to my rafter work. I need to know the rafter lengths from the fascia to the ridge. I'll compute and factor in the heel if I deem it necessary. Usually it isn't becaue we always work with energy heel and the rafter don't actually get a birdsmouth cut into them. Instead they get heel blocks.
So, this discussion is interesting, but the only reason I stepped in was to say that equal heel heights are an overrated thought process. Once you start thinking of your roof from the facia to the ridge, you'll quickly understand that you're wasting a lot of time an energy thinking about heel and walllines!
Always full of wind my friend,
blue
The reason that you are coming up with a minor heel stand height is because the ratio of the overhang widths is slightly different than the plan view ratio. To have the overhangs equal the plan ratio they should be, 9-5/8 to 14-1/2 or 9-1/2 to 14-1/4. These overhangs will equalize the (1-1/2” hypotenuse) placement triangles at the corners of both the fascia and walls.
This sounds like esentially what I said earlier on in this thread: the overhangs that were given were throwing the layout off a little. Just a small shift in the overhang on the steep side would correct the problem. But the OP said the overhangs were carved in stone. But it didn't make sense to me that someone would frame up their fascia, then begin to figure their trusses or rafters.
I would adjust the overhangs to the correct ratio before I complicated my roof layout and changed a heel height to satisfy the minor discrepancy
I would do the same. Gene said he didn't want to shim, and Blue said with trusses you can't, because of throwing off the ceiling height. All the more reason to make the small adjustment in overhang to get your truss layout correct first, and avoid all that.
"he...never charged nothing for his preaching, and it was worth it, too" - Mark Twain
Mr Jalapeno,
Now I know why I spent all the years here long ago. . . It was the entertainment ;-)
Forget the 36" HAP how about the hip that's off the plate and he comes back later to block it down. . .
You can't make this stuff up ;-)
Edited 3/19/2006 10:13 am ET by Joe
Mr Jap, you and Joe are so close minded, you cant see the forest for the trees!
I've already stated that we always have energy heels. Often the heels are as much as 12 or 14 inches. If you were to size a framing member to cut a birdsmouth, you'd have to spec out 16' microlams!
Hahahahaha! A 2x 6 will meet code perfectly and you want to spec out microlams....just so you can cut a birdsmouth!
Now, if you'll stop and ask intelligent questions and stop trying to prove that I don't have any clue....maybe you'll learn something.
We rarely play with low slope roofs...because of style and snow loads. Because of that fact, I don't think I have to cut a birdsmouth in 1 hip out of 15. On 14 of them, I have to add a heel block.
You can call me crazy if youwant, but if you took your attitude onto one of these frames, the super would toss you out and you'd never work a job for him again....unless you decided to open your mind and just work with the products (truss heels) that are sent to you.
One of the most important factors that determine heel heights is the height of the windows, the size/style of the frieze and fascia. Those factors are drawn on the elevations and the truss company starts with that fascia line to determine his heel heights. If you arbitrarily decide to lower the heel heights to create a birdsmouth, the soffits would be dropped down into the windows. If you wanted to raise the walls, you'd have to send back the truss package and send back all the studs.
You guys are the ones complicating this thing by trying to use the corner of the building as some sort of starting point. That corner means nothing!
NOTHING
NOTHING!
BLUE
Agreed, Blue!
A trussed irregular hip end set can be built on block-ups on the ground, then craned up into place. We can triangulate the hip truss at the corner to get its angle right.
The only thing with which we'll be concerned when setting it on the walls is the overhangs. Let the hip fall where it may.
Gene, we build the hipsets on the ground, but I normally don't bother with the hip, nor all the jacks. I do most of the larger jacks on the ground though. I don't like to spend too much time creating a pefectly level and flat surface. Occasionally I have used the deck before I got walls in the way. If I do that, I can snap lines that emulate the fascia line and then do everything, including the hip.
When we crane either set up, we set both side perfect with the fascia line. This insures that the hip will also work perfectly when we cut and place it. I never even think of, or look at a layout for the hip, or the hipset....instead I let the tips of the hipjacks locate me. After all, I'm focusing on creating a perfectly flat roof line at the fascia...aren't I? I don't care that the heel line is perfect...I want the fascia line perfect!
I've never met another carpenter that can grasp that idea....I think you do because of your extensive use of the cad system. You don't seem to be locked into some obtrusive layout sequence...
blue
Woohooo.
I shoulda put some panythose one too.
blue
Really, do you think I would order a mirco-lam hip just to put a heel cut on it? You are grasping at extreme design scenarios that are beyond the general concepts being discussed.
Well excuse me Mr Jalp....please explain how you'll cut a birdsmouth in a 20" heel....which is very common on our garage packages, when you are installing a 2x6 hip?
blue
blue,
I would cut a heel and leg it. ?
Come on man, I'm sorry...
Mr. Jalp
Blue,
Yes that cleared everything up! I’m absolute certain now. . . Gene,
That’s no good. . . DXF or DWG format would work. I have an autocad platform.
Try this. I exported the work file in .dwg.
There are lines that represent a single ply hip truss. The heelstands are 0.16666 different due to the overhangs specified. Had the overhangs been specified in the ratio appropriate to the primary and secondary pitches, the truss heelstands would be identical both ways.
A timbered arrangement is modeled, also. It is the same model I used to develop the drawings I attached to an earlier post here.
I consider the roof edge to be the outer top edge of a 2x subfascia. In plan view, that outer subfascia line is the overhang. Common rafters and common trusses, in plan view, come to the inside of that line, 1-1/2" inboard.
Everyone is over-thinking it the over hang can be manipulated with creative blocking,
cut hip rafter short at tail to make the 8/12 soffit the correct depth ruh faicia long and block end to accept 12/12 facia and soffit !!!
Huh? Could you post a pic, or explain a little further?"he...never charged nothing for his preaching, and it was worth it, too" - Mark Twain
hey i have to go eat supper right now but i'll get back to you in about an hour
drew a skech however I'm still learning my new HP 6200 so I can't send it but , leave the hip long. then make tails on deep over hang the same as the short ones in lingth.
then use a strsigrt edge to deturmine cut you will olny have to cut one side of the hip run short point of pine facia to long point of hip .and make connection as usawal then when roofing gust slightly offset cap shingles,If a another carpenter cant see it from 50 feet away. Homeowner won't see it from 10 inches.