Hi all,
Framing the roof on my 24×64 workshop. Stick framing the roof with 2×10 rafters and need to place 2×8 collar ties in the lower third of the height of the roof.
Do I add the collar ties as I frame each pair of rafters or wait till all rafters are up, run a chalk line and then nail them up?
Thanks,
Marco
Listeners write in about removing masonry chimneys and ask about blocked ridge vents, deal-breakers with fixer-uppers, and flashing ledgers that are spaced from the wall.
"I have learned so much thanks to the searchable articles on the FHB website. I can confidently say that I expect to be a life-long subscriber." - M.K.
Dig into cutting-edge approaches and decades of proven solutions with total access to our experts and tradespeople.
Start Free Trial NowGet instant access to the latest developments in green building, research, and reports from the field.
Start Free Trial Now
Replies
Depends. What's bracing the walls now?
Whoa!
you are about three steps ahead of the questions you should be asking here already.
unless you are parking a lot of posts in the middle of the shop, you are obviously not using a 64' long structrual ridge beam, so rafter ties are a must. Whether you need collar ties or not depends on local codes. Placement in the lower third defines a rafter tie, not a collar tie which is placed in the upper third.
Why not use trusses on this? Seems like the logical choice to me. Can you get joists to use for rafter ties that are 24' feet long where you are?
Welcome to the
Taunton University of Knowledge FHB Campus at Breaktime.
where ...
Excellence is its own reward!
You should use a tie on your collar when you go to church. Any other use requires prayer as well.
hello?
Welcome to the
Taunton University of Knowledge FHB Campus at Breaktime.
where ...
Excellence is its own reward!
Collar ties go in the upper third of the roof. Here we are required to install a collar tie on every 3rd pair of rafters, assuming the rafters are on 16" centers. Install your collar ties as you go.
Rafter ties, (lower third) or ceiling joists are installed as you put up the rafter pairs, unless you have a fairly sturdy temp support for the ridge board, which often is the case. The rafters exert significant outward lateral force on the walls, hence the need for rafter ties. Assuming the rafter ties are going to form your ceiling I guess you are concerned about keeping them all in the same plane for a nice flat ceiling. A rotating laser level would perfect for that. Another method would be to tack nail a rafter tie on every other rafter pair about a foot higher then the perm position. Once you have your roof "stacked" chalk your lines, install the remaining rafter ties in the perm position, and then lower down the high ones to your chalk lines.
Marco must have fallen while framing this roof. He has not been back to view answers or participate in the conversation he started.I'm thinking that since he mentioned the lower third, that he is aiming to gain ceiling height by lifting, hence this complication and question.So he should probably string his walls straainght and brace them well, then onnect them to each other oposite with some semblaance of a ceioing joist/rafter tie about every 6-8feet temporarily to prevent spread. Then he can frame the roof rafters and add collar ties as he goes, releasing the temporaries allong the way.Whatcha think?
I'd love to hear Framer and Blue commment on this one
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
I'm good with those methods and I guess some of those things were assumed (in my mind). Probably my bad!
And you are right - after typing my post I was thinking there are at lease 4 or 5 guys here who frame all day every day and would have the most efficient methods that would yield the best results, and they could do this in their sleep. For example it seems like the perfect scenario for Tim's U. gang cutting.
Like Don said, above, when the floor is a flat level olane, what we often do for these is to cut legs the length that we want the tie to be above the floor. Two men can each have an end of the tie against the rafter, with a leg to the floor cut of a 2x4 and use the other hand to gun nail it in place.I sense that the OP is less experienced and maybe even working alone so that might dictate his methods...
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Hi All,
Thanks for all the replys. Yes, I am a DIY working alone, and with help when I can wrangle it. I am a Chef for a living, so I feed my temp crew/neighbors/students well when I am lucky enought to have them help me.
I was outside all weekend nailing up the 3/8 plywood shelthing on the building and laying out for the rafters, so sorry for the late reply.
Thanks for the clarification of rafter ties instead of collar ties. I did not know there was a difference.
I have the walls braced every 8ft on the inside of the bulding and there is a 4' brace wall 34 feet down each side.
I like the idea of a come along to hold the walls togeather and add the col...er, Rafter ties later.
Not using trusses because of cost and headroom.
Thanks again for all the help.
Trusses aren't as expensive as one may think. Then again, they are a bit more than stick framing.
There are different style trusses as well, that will provide more headroom.
Anyhow, if you must stick-frame, I'd support the ridge beam with temporary posts and then attache rafters. Double check wall to wall dimensions before you nail off your collar ties to be sure that the walls aren't bowed out (or in for that matter).
Now, I've always been of the belief that collar ties are to be installed in the lower third of the roof and rafter ties would go into the upper third, which is the opposite of what two others said already. My way makes sense to me as the "collar" would be formed by the top plates.... rafter ties would then go into the rafters, higher up. Furthermore, I don;t believe that "rafter ties" are considered as structurally dependable as collar ties (based on my usage of the terms).
Collar ties are used, in my experience, in the absence of ceiling joists in order to provide the structural element forgone by the elimination of the joists.
Have I been wrong all this time? If so, this would be the second time.
http://www.petedraganic.com/
Yes you are wrong. I made similar omments yers ago here and had a dozen references handed to me from definitions to codes quotes. I learned whih is which from that humbling experience. Also, he is not using a ridge beam. He might be using a ridge board. That distinction made, using temp supports for it is a good way to deal with this situation too.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Piffin , I guess that means I'm wrong too! :) just not my second time, or third or fourth or.......well you get the idea.
I knew I should have waited a little longer to post.
Geoff
To be fair, it is common mistake to interchange the two terms, but take a look at this oficial sitehttp://www.tdi.state.tx.us/wind/images/artwork/306.1.4B.gif
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
i like the tx in tha url
The JLC Field Guide says 'collar ties often are placed near the ridge', AND, 'To effectively keep rafters from spreading, collar ties must be in the lower third of the rafter'. (Page 146 and Figure 2-89)
(can't trust nothin' from TX)
I have not used collar ties in years. Ceiling joists, yes, but collar ties, no. In fact the last time I saw them on a drawing, the inspector told me they were useless.
Edited 11/1/2006 9:42 am by gb93433
FYI, here is a link reference to the code we use here in NC. It is based on IRC2000. Specifically, read the last sentence on the page. Granted, it refers to them as "collar beams".
The way I make up my mind though on stuff like this is to collect information from a number of resources and make a decision from there.
Doing a Google search for "collar tie" rafter might be a good start.
In this case I use the same terminology the BIs here use for obvious reasons. Also, in a code seminar I went to some years back, we were taught collar tie = upper 1/3, rafter tie/ceiling joist, lower 3rd.
I guess part of being "educated" about this stuff includes knowing that there is some differences in use (misuse) of terminology in certain topical areas, and knowing alternate terms for a particular item/element/etc that those commonly used in a particular geographic area, etc.
Edited 11/1/2006 8:08 am ET by Matt
Well, here is the whole story -
Some places do use the terms collar and rafter tie interchangeably, even in officialdom. but regardless what we call it, th eones placed in the upper third do nothing to prevent spread under load. these collar ties are to prevent the roof from opening or hinging at the ridge in high winds. Southern code3s require collar ties in the upper third at least every four feet as a way of keeping the roof togehter vs tornadoes and hurricanes.
The rafter tie is placed in the lower third and is theree to keep the walls from spreading under load and the ridge from sagging. The greatest stresses on it are on the connections between it and the rafter. in most cases, ceiling joists function as rafter ties
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Pete, I'm standing on your side of the fence, collar ties are the lower connectors, which in essence are ceiling joists.
As for the rafter ties (upper third) I do believe there is some draw back to using them since they impart a load transfer that needs to be put into the equation.
Geoff
Our remodel project earlier this year had a roof framed just as you've described. It's so very hard to accurately and quickly attach the rafter ties as you go that we left that for last, holding our plates together via come along and shooting a level line over all 50 or so rafters at once.
If all new construction and the floor is uniform it might be an easy measurement to hang rafter ties as you go, but for something like a smooth finished ceiling the flatter the better.
While collar ties are required by IRC only every 4', our engineer wanted them on every rafter.
Our rafter ties were up to near the 1/4 mark and the engineer spec'ed rafters 2" deeper than minimum code.
Beer was created so carpenters wouldn't rule the world.