What would be the proper (UBC compliant) placement and size of collar ties for a 3/12 roof of 2X6 framing 24″ OC, with a 1X8 ridge “beam”. I have removed the 8′ high ceiling joists which held up the sheetrock lid. I wish to create a more open ceiling. I believe I’m required to use at least 2X6’s, placed 1/3 of the total distance from the top (1/3 to the top or bottom of the collar tie I don’t know), but I’m not certain. My engineer said to do whatever is in the ’97 UBC, does anybody know the particulars.
Thanks
Juan Carlos
Replies
1/3 down from the top was my understanding of the highest location for collar ties, although I'm not sure that with a slope as low as 3:12 that they will provide enough resistance to lateral thrust when they are up that high. Just a hunch....
If you only have 2X6's for rafters you may need to sister them up to get enough depth for insulation. Aren't you required to use R-30 minimum?
R-38 actually, and yes I will sister on members to accomplish this, but I plan on putting the collar ties on the existing 2X6's.
Juan Carlos
You didn't say what the span was from wall to wall, but I gotta tell you, Juan, I don't like the sounds of this at all. Those ceiling joists you say you removed did something way more important than hold up the ceiling. They kept the walls from spreading, as gravity tries to pull the ridge straight down.
First off, I hope you have temporary posts under that ridgeboard. If not, you probably already have a sagging ridge, especially on that low a slope.
Now, others might tell you how to install "collar ties" to compensate for the lack of ceiling joists, but I'll tell you this - you're asking for trouble. You might, and I stress "might" be able to come up with something satisfactory, but collar ties, 1/3 of the way down from the ridge, or even 1/3 of the way up from the plates, isn't going to work. I don't care if you double them, through bolt them, fasten them with tie wire, they will not keep the roof from dropping or the walls from spreading.
Thanks for your reply. However, I am aware of the role the ceiling joists play in the roof system, the tensil strength they provide, and my question is specific as to how the 1997 UBC specifies the placement of collar ties, not how to properly do the demo. This project has a structural engineer involved, and anal-retentive municiple building inspectors too, Both entities say that if the existing ceiling joists are removed all that has to be done is to install collar ties according to the 1997 UBC. The span is 24 feet, outside of top plate to outside of top plate.
Thanks,
Juan Carlos
The PROPER placement of the collar ties is 3/3 of the way down from the ridge.
Mr T
Do not try this at home!
I am an Experienced Professional!
Juan-
how come the engineer won't tell you where to place your collars? that is what engineers get paid to do.
collar ties have become old school-
ties will keep your ridge in place and the walls won't move until a big wind shear hits them and then those collars won't be enough to counter the uplift and something will give and you lose- and if those forces are sustained and your envelope is compromised the walls are coming down.
hub
I'm with Jim on this one.I believe this situation calls for a structural ridge to support the rafters from the top and carry the load through the end walls if possible.A little steel strapping to tie the rafter tops together and no collar ties would be necessary.
Juan, I believe the collar ties should placed 1/3 of the distance up from the top plate,in your case about 12".This doesn't seen to increase head room much and a better solution might be to add a structural ridge after you sister the rafters.Make the ridge part of the finished ceiling.
Vince Carbone
Vince,
Now that is an excellent idea. Sister in 2X10s then put a ridge underneath. It didn't seem like a viable option until I finished the tearout, but after I read your suggestion and had another look at, I think it can be done. The ridge doesn't go from foundation wall to foundation wall and load transfer will be challanging on that side, but it can be done. Thanks again.
Juan Carlos
Another vote for what Jim Blodgett said.
Don't care if an engineer/inspector is involved or not - it ain't right.
How's it going, Norm?
Cut the small talk and get me a beer.
Removing ceiling joists to raise a ceiling and framing in an alternate roof system happens dozens if not hundreds of times a day in this country. It's called modernizing, updating or more commonly remodeling. "It's just not right"... are you people serious. Do you always shy away from doing things just because they're hard. That's Ok I guess, leave the challanging jobs for the rest of us.
Juan Carlos
Maybe you need to get your head out of your a$$ and realize we're not saying it's wrong because it's hard.
We're saying it's wrong because it's inadequate structurally.
The fact that it gets doine frequently has no bearing on whether or not it's a good idea. Stupid things are done daily, probably by guys like you.What's up, Normie?My nipples, it's freezing out there.
I agree 100% that removing ceiling joists is a great way to open up a building. I'm just saying that replacing them with collar ties is dicey, at best, especially on a low slope roof, like a 3/12, with 2x6 rafters spanning...what...12'4" or something?
You could install a structural ridge, like Vince said, or maybe remove every other joist and double the ones you leave-that can look nice, or run a pair of beams perpendicular to the rafters, say 1/3 of the way down from the ridge. Or maybe strategically place a couple beams to replace the original joists and leave them exposed, steel rods with turnbuckles look great in certain applications.
There are lots of ways to do what you are talking about. Collar ties just isn't one of them.
Juan, what's your problem man? You asked for advise and got it. You don't like what you hear and accuse everyone of being lazy or somethin. Never mind, rip em out, do your thing. Gimme a call when you need to borrow a half dozen come-a-longs and bottle jacks to put your roof back where it belongs.
Maybe you forgot to tell us something important or there is a lack of communication. Those ceiling joists do serve a purpose other than holding up your sheet rock. I've seen a ton of roof failures, even on new construction when builders decide to eek out a little extra height from a cieling, or decide to make a room cathedral where the roof wasn't designed for such a thing. Everyone is just trying to give you a heads up to what problems may lie ahead. Everyone makes mistakes, even archs and engineers.
Ripping out the ceiling joists and THEN deciding how to support the roof is moronic at best and stinks of ignorance. Everyone was trying to be polite about it, but appartently that doesn't work with you. DP
Juan heres a simple test.
Take two pieces of scrap plywood and and make a small mock up of what ever pitch your roof is. Do not put anything going along the bottom edge of the triangle you just created.
Now put it on the ground and stand up on it. What happens?? It spreads apart and flattens out.
Now make another one, only this time every so often attach some 1x (or what ever) strips going across it, now stand on this one, what happens? Unless your very much over wieght, it should hold you up
Now imagine the first one sitting over your head in the room you just ripped the joists out of.
I havent got much sleep the last few nights so this might not be completly clear and I dont feel like re-reading it right now, if you dont understand let me know.
View ImageGo Jayhawks
Edited 3/13/2003 2:53:05 PM ET by CAG
juan- your engineer should be answering your questions.
if you have an engineer and he won't tell you how this needs to be framed- get another.
code compliance won't save your behind.
can you afford for your roof system to fail?
The old code called for collar ties 1/3rd of the way down on every 3rd set of rafters. Six nails into each rafter. I'm not sure if the size of collar tie was spec'ed, but we used a lot of 1x4. Is this a grandfather clause deal?
Like the rest of the folks are sayin', where do you work that an engineer won't spec plans that he stamps? Or did he stamp them? And why doesn't he have access to the '97 code? Sounds sketchy.
Seems like a pretty touchy subject...I like Vince's take.
Good luck, I'd like to know what you work out.
EliphIno!
Billy, your collar tie specs are on target, however that is under the presumption that there are ceiling joists also tieing in the rafters. He has removed the ceiling joists, therefore without wall ties or a structural ridge chances are he is in jeopardy. There may be other variables involved with his roof that haven't been mentioned, however, based on the information given his situation will fail. "BASED ON THE INFORMATION GIVEN"
I was just regugitating the code...didn't say I liked the idea, or the code...I have taken out 2nd fl joists and put in collar ties on a 6/12, but, I also put in steel tensioning rods. Oh so discreet. EliphIno!
Now I getcha. Steel tensioning rods huh? Through top plates? O/C spacing? Just curious. DP
Yup, through the bottom of a double top plate,then through the sheathing, a beauty block and a 1/2" steel plate on the outside. The rods were threaded on each end and after tensioning, we cut off the extra that was out past the nut.
I can't remember the exact centers, but it was at least 8' and maybe 10.
Confused yet? EliphIno!
DP... i tried your fax... no good... sent you an email too.. check it outMike Smith Rhode Island : Design / Build / Repair / Restore
I'm assuming you're not going to be sticking your head up into this additional "headroom", but rather you just want the increased volume in the space ...
What about using steel tie rods between the top plates of the opposing walls? Then use a steel rod on center from tie rod to ridge to keep the rods from sagging. Done right, and painted to disappear or contrast, this can be a real nice look.
Formerly BEMW at The High Desert Group LLC
I am an engineer. Since you have one, ask him what to do.
3 questions for you:
1) What is the tensile load in your tie?
2) What is the shear load in the nails that join the ties to the rafters?
3) How much snow load do you have?
Engineers get paid to answer those questions in a safe manner.
The jerks her just get a good laugh when you follow their advice.
um- what jerks george?
how many houses and room additions have you built?
doesn't matter- point is to problem solve and save name calling for tomorrow or the next day.
In other words give your advice and shut up-
If Juan doesn't act on it it is his problem
jerks are universal-
get it?
If eveyone here is a jerk, why not find a different place to visit?View ImageGo Jayhawks
I think that was actually a failed attempt at a humorous tag line. I rarely give that kind of credit out, so I may be wrong....that's not a mistake, it's rustic
I think we hurt his feelings. He hasn't read any messages since sometime Thursday.Would you like a beer Mr. Peterson?No, I'd like a dead cat in a glass.
Maybe a little birdy or two landed on his ridge and without those pesky drywall nailers up there the rafters kicked out?
Think we should call someone to drive by his place see if hes under a pile of roof ??:)View ImageGo Jayhawks
Guess we oughta leave him alone.
He's not the first one in this forum that got all bent out of shape when they didn't hear what they wanted to hear.What's goin' down, Normie?My butt cheeks on that bar stool.
Probably,
But hell dont ask a question if you only have answer in mind. I dont no much about roofs, but I know whats wrong, and any time you remove a piece of a structure without making up for it is just bad karma.
By the way I keep trying to convince my boss we should be using trusses instead of framing roofs :) But its selfish Im just tired of climbing up and down latters.View ImageGo Jayhawks
" I keep trying to convince my boss we should be using trusses instead of framing roofs"
You're a STICK FRAMER ???
I'm gonna email Brian and see if I can get you banned from this forum. Can't have your kind around here.............I'd horsewhip you if I had a horse.
First of all I am not a Framer, I keep trying to tell that to my boss but he wont listen....Guess he expects me to learn....
And I am not sure if trusses would apply to half of our jobs anyway, its all remodel and usually trying to match whats existing or work into it.
But I hate roofs, I hate dangling off ladders, I hate running up and down ladders 10 times in a row.View ImageGo Jayhawks
"But I hate roofs, I hate dangling off ladders, I hate running up and down ladders 10 times in a row."
Better stay in school, CAG.
And, um, try not to hate, not good for your soul.
ok I strongly dislike roofs, ladders don't bother me, but today was ridiculous, Trying to get the rafters up, but they were all cut the wrong length, fortunately to long and even more fortunately not by me.
I'm just ranting about a wasted day below read at your own risk.
So they go up, wrestling with the ridge beam which wasn't level, so that had to be adjusted, then the rafters are to long and pushing the wall all out of wack, which was messed up yesterday when someone had the bright idea to try to pull it in because it wasn't plumb, but it wasn't plumb because the wall that it met up with on the existing structure wasn't plumb so it had to be the way it was,
Then I go down to the ground to see what the wall looks like from the side, the wall is so racked it looks like an ocean wave, so then the rafters have to all be taken down, it was only about a dozen or so rafters but a waste of time none the less then the wall has to be pushed back to were it should have been in the first place, rafters get cut and go back up. Wasted about 30 man hours on something that should have taken half that at least. Now I don't write the checks so it doesn't bother me to much but waste like cuts my chances of getting a raise.
Man I feel better now that I got to let that out. Sorry but you just happen to be here when I decided to rant.View ImageGo Jayhawks
Get rid of the ladders and walk the plates bro, it's the only way to go. Tell your boss to get them walls straight before he starts feeding ya rafters. Up the ladder once and back down it once. And we are ALL framers!
"Your a stick framer?" Is there any other way to do it right? :) Call me a purist, but I LOVE cutting roofs! Would a truss designer be considered my competition? Man this business is getting crowded.
Heck, I was just poking fun at CAG.
Althought - Maybe a truss vs. stick framing thread would be fun. We've hardly had ANY arguements around here lately.Go, and never darken my towels again.
I just found this very entertaining thread.
Something is fishy about the info that Juan provides here. Given the brevity of what he reports that the engineer said and the atitude he diosplays here, I read his conversation with the engineer this way -
Juan (dials Phone...)
"I need to know what size collar ties I need and where to stick them"
Engineeer
"I'll need to come visit the job to inspect what you have, document the conditions, and write a spec sheet for you. The basic minimum cost for this sevice is normally $250"
Juan
"I realy don't want top spend that kind of money. I just want to know...Maybe you can give me a bnrief idea over the phone"
Engineer
"Just look it up in the UBC. It's all right there. Click!"
Juan
"Damn money grabber! I can do this without his help. I'll just get an answer from these guys at Breaktime..."
Excellence is its own reward!
I agree.I got the room built. How do I get outside?
AWESOME!!! I haven't noticed him back, however. I think CAG was right!
Or Maybe
j:Hi I need to know where to place my collar ties
e: Ok I need to come out and visit
j: Ok
Engineer comes over, Takes one look up at the missing (drywall nailers) and heads for the door.View ImageGo Jayhawks