A trussed arrangement for a hip roof has stepped-up trusses from the girder up to the peak.
I have always seen these dropped, so that 2×4 members can run across the tops to define the hip lines for sheathing, and also be run to align with the hip commons hung from the girder, to provide nailing for sheathing.
Preferably, the truss supplier furnishes hip cap trusses, which look like gable end trusses with all the webs vertical, and those hip caps, which I call “sleepers,” just lay on, get spiked down, and it’s time to start sheathing.
A new truss supplier says, “We’re sorry, we don’t do those.”
I’m saying, “Why not?”
Any truss gurus out there that might know? Is there a software issue? This same supplier that says hip caps cannot be done, is happy to do gable end trusses.
Boss?
Replies
Tough question, and lots of possible answers.
It could be that they don't want to do them because there's typically only one of them. As you likely know, building one of anything in a manufacturing process is more expensive than building large quantities.
It could be that they had a hard time getting them figured out and built right. That doesn't happen automatically.
It could be that they had a hard time getting the designers to do them correctly. Until recently truss software didn't do these automatically, so they had to be figured by hand. (The software we use does them automatically, but does them wrong)
Maybe they had a hard time getting their customers to install them correctly. That doesn't happen automatically either.
Or it could be that they don't like change. they've never done them before, and they don't see any reason to do anything differently now.
Or they could just be jerks. Or some combination of the above.
.
BTW - Hip frames have only been common for maybe 6 or 8 years. I had never heard of them before roughly 10 years ago.
I thought maybe if I just gave them the specs for what we need, and we need a pair of them for each of two different hipped roofs in the project, they could do it.
Whaddya think? One pair shown thus, the other is slightly smaller. This bigger pair is just under their shipping height limit of ten feet.
View Image
"A stripe is just as real as a dadgummed flower."
Gene Davis 1920-1985
Gene, when I framed in MI, only 1/4 of the suppliers shipped those types of trusses.
My experience is that they were trickier than what you might think to get them to work properly and I'm sure there were a lot of framers that either installed them wrong or just left them lying on the ground. There are a variety of reasons why they didn't work as easy as they seem they should.
Personally, I liked them and early in my career I'd make my own. In my later years, after I had the Skytrak and crane onsite, I decided that I really didn't like them because I prefered to drop a bundle of sticks up top and run the "layon" piece by piece. I preferred this method because I could more easily make the fine tuning adjustments with the hip loose. If the hip was all assembled and tied to the vertical struts, it was sometimes necessary to snap lines and cut the hip up in the air.
One clue to my theory about why they didn't ship them all the time is that often, when they did ship them, they were intentionally smaller than required by an inch or so. I actually appreciated that because we'd set one hip perfect, then booger in the other without every having to do the dreaded "snap line and rip" act while dangling by my toes.
Giving them info probably won't help. Your info may or may not be correct anyway. As Blue said, it's not as easy to figure these things as you might think. You're fitting a 3 dimensional object into a 3 dimensional space where the pieces are at odd angles to each other. You're probably better off just asking the company to make an exception and provide the things this time. Or just stick frame them.
Tell a man there are 400 billion stars and he'll believe you;
Tell him a bench has wet paint and he has to touch it.
We had one truss suppier that would do them.
Hated them because if you have to play with the trusses for whatever reason, they wouldn't work out.
In a perfect world, they would fit everytime, but we don't live in that world.
I like to think I live in the same perfect world that a fully competent framing crew inhabits, when it comes to accuracy in building frames.
You know who I mean. Those guys that can snap out a deck, tell their cutter that of course the lines all match the plans, and to start cutting the entire stickframed roof.
What works for stickframed works for trusses, in that perfect world I live in.
Haven't seen a hip cap thrown away yet.
That said, you cannot just trust the truss engineer to get all the details right. Just because he or she has an expensive truss CAD package for use in designing, it doesn't mean all the entry data all got typed correctly. I use 3D CAD software so I can validate every single number on all those truss detail sheets that come with a submittal package, and do not sign off until everything is right.
There is a reason that those truss detail sheets show dims as FT-IN-SIXTEENTHS. It means that is the tolerance to which they are designing and specifying. And cutting, with their computer-driven saws. Just like the numbers that Ms Roof Cutter's Construction Master Pro calculator is giving her to cut those hips and jacks.
View Image
"A stripe is just as real as a dadgummed flower."
Gene Davis 1920-1985
While living in this perfect world, we have tyo account for all the imperfect trades. ie. masons.
As I get older I realize it is harder And harder to get a mason to build what is on the prints.
This perfect world, is quickly becoming more and more imperfect as the "older" generation diapears.
If I understand what you guys are talking about, this is the first time I have heard of it. True, I have not had much experience using trusses for a very very long time and even less using hip trusses. Not since I got out of the prefab business.
Is this a frame/platform the lays on top of the hip trusses to provide a better/more uniform nailing ground for the roof decking? (Are the frame member on edge or on the flat?)
If so, I can see how this could be an asset since hip trusses can be so squirrely to build/install perfectly. I also can see how building one of these to fit properly can be a problem for similar reasons.
If I am seeing this correctly, are you likely to have to strip the ceiling for similar reasons?
With all the practice it get, I still never get used to showing my ignorance.
I'm not working, so I don't have access to pictures that I could post that show how hip frames are used. Basically they take the stepped down (flat top) trusses and drop the flat tops 1.5". Then a "hip frame" truss is built to lay down in there. It's 1.5" thick and basically looks like a gable truss. The benifit is that it eliminates the need for blocking between the trusses when you put the plywood on.
People find it far easier to forgive others for being wrong than being right. [J. K. Rowling]
This job used them at three different sizes, and I highlighted them in yellow in the pic attached.
The largest was too big for shipment in one piece, and if you look closely, you can see that it was split so as to ship in two parts.
All fit just fine.
View Image
View Image
"A stripe is just as real as a dadgummed flower."
Gene Davis 1920-1985
I like to think I live in the same perfect world that a fully competent framing crew inhabits, when it comes to accuracy in building frames.
You know who I mean. Those guys that can snap out a deck, tell their cutter that of course the lines all match the plans, and to start cutting the entire stickframed roof.
What works for stickframed works for trusses, in that perfect world I live in.
Gene,
I don't live in a world where things are perfect (ask my family) ;-)
I think that the trusses should work out. It doesn't take much to snap square and parallel, but where its tough is when the foundation is off. Stick framing, we can make the adjustment to the snapped lines, and with trusses its a little tougher, but they work every day 1000's of times.
having said that, the hip sets I've worked on, had the top chord of the jack truss run long. And they worked out right on the money.
http://www.pioneerbuildersonline.com
View Image
From Lot 30 Muirkirk
http://picasaweb.google.com/TimothyUhler
Tim, you said:
It doesn't take much to snap square and parallel, but where its tough is when the foundation is off.
I agree completely.
Which is why, in my perfect world, the truss order is not released until the foundation is proofed. The deck we will get on that mess, if it is a mess, will nonetheless be all rectilinear. A plan dimension of 28'-6 may turn into 28'-4 1/2", but the deck will have the 90s where it is supposed to, and 45s or other angles where else they should be.
You would not plate out for a roof if the span changed a couple inches over the run, would you?
If the proof-out results in different numbers, no matter how small, the truss drawings and details are changed accordingly. Just like your precut stick roofs.
On one occasion only, we found a truss plant remarkably quick in getting out replacement parts, when the error was theirs and the trusses did not match their own approved details.
When it is one's own error, in not checking submittals carefully, or in letting a bad foundation get decked with not-to-plan dims without going through the revise and resub cycle, it's hard even to get the truss guy to pick up the phone.
BTW, in a conversation with the truss supplier's rep today, they have agreed to make hip caps for the upcoming project. Business is so bad lately they would probably truss a dog house.
View Image
"A stripe is just as real as a dadgummed flower."
Gene Davis 1920-1985
Your "sleeper" picture is a good example of a truss set that I've had to frame, many, many times. I can say with certainty that I would NOT want those "sleeper" trusses sent.
The reasons vary from job to job but there is consistently one main reason because of the roof framing techniques that I use. I like to work each section of the roof ALONE. So, when I get to that end where the split sleeper is, I don't want to call for help to adjust those beasts. I much prefer to grab single sticks of linear plate stock and make a level cut, nail it to the girder, then walk up the roof pulling the roof into alignment and nailing as I go.
I normally do the same with the hips and I tweak the truss alignment to bring the theoretical hip line into something workable. Notice that I said "something workable". That means that there is normally some variation in all the planes and alignment....often as much as 3/4" for whatever reason....don't ask me....it's one of the mysteries of framing.
Anyways, I find it signficantly easier, and therefore faster, to tweak the three main elements (the two hips and the center common) of that truss. After that, it's a simple "slap down and nail" of the remaining members.
Keep in mind that I ALWAYS have a great place to work from because I sheath the lower hipset before I start any work on the stepdown hips. I have a place for my saw, material and theres normally a pile of staged plywood on a rack. Or, I might be working out of a Skytrak box, which makes it all very easy.
I've yet to see a set of hipsets layons like that fit to the 1/4" on all the two main hips and yet, that's the tolerance needed to put a quality sheathed roof together.
To give you an understanding of the amount of time it takes to stick build that "sleeper" up in the air...think a half hour at most. My experience is that I have to fuss around with the shop supplied layons that much...so I'd rather do it myself.
Thanks Boss. I think I get the idea. It's funny how time slips away. When we were doing hip roofs, we used a girder truss and hip trusses with varible length jack trusses.
If everything was not right on, it was tough to get them to stay on centers so the decking would work out. That's why I tried to avoid the use of them. It could be a problem to explain over the phone to your builder/customer, which was in another State, that the problem was because his foundation was out of square and his walls were not plumb.
You all are talking about full length trusses with varying flat sections to create the hip effect. If I remember correctly, in those days, the steepest pitch we use was 4/12. That made the last few of trusses very flat, (some not much more than simple beams) limiting their span. There were many small towns that we shipped to that would not allow any type of truss construction without our jumping through all kinds of hoops to get them to accept them.
CCA built them for me last year so it isn't everyone.