# Cutting rafter ties ??



## tpolk (Nov 7, 2009)

do your ceiling joists span outside to outside and are they nailed to the rafters?
do the ceiling joists attatch to each other with an adequate lap in the center of the building and are the resting on a wall?
size of collar ties?


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## scatkins (Sep 22, 2008)

Here is a simple cross section of the roof. THe red is the "collar tie" that I would like to remove.


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## tpolk (Nov 7, 2009)

I understand that part, need help with the other parts


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## scatkins (Sep 22, 2008)

tpolk said:


> do your ceiling joists span outside to outside and are they nailed to the rafters?
> do the ceiling joists attatch to each other with an adequate lap in the center of the building and are the resting on a wall?
> size of collar ties?


1) Ceiling joists sit/attached to exterior walls as well as interrior walls. Not continuous ceiling rafter spans. Split up with a hall that runs parallel with ridge beam. Width of overall house is maybe 40-45 feet. 

2) Ceiling rafters sit on exterior walls (attached as well). Not sure they are attached to all ceiling rafters but some are.

3) Collar tie look to be 1 x 4's maybe 1x5's but are really saggy and twisted. Definitely not under compression or tension...

4) And While the ceiling rafters aren't continuous from one side of the building to the other, I'd say the overall they are interlinked in such a way that it forms a continuous link, which is what I think you are sort of asking..


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## scatkins (Sep 22, 2008)

tpolk said:


> I understand that part, need help with the other parts


Sorry, you were quicker than I was, was still composing.....


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## Gary in WA (Mar 11, 2009)

1. Measure the span of the rafter.

2. Measure the size of the rafter.

3. Are the ceiling joists face nailed to every other rafter?

4. Measure the on center of the rafters-16" or 24"?

5. Is the ridge a board (1-1/2" wide) or a beam (3-1/2-5-1/2" wide not high)?

Be safe, Gary


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## jaros bros. (Jan 16, 2009)

Generally it is unlikely that they were placed there unnecessarily. You need to determine what is holding the walls from spreading outward from force exerted on it by the rafters. If the ceiling joists are doing this, they can be removed. If the ceiling joists are not continuous and tied in and working as a system, then they need to stay.


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## COLDIRON (Mar 15, 2009)

Sounds like you need to have a carpenter or someone in the framing business look at the house, it"s hard to answer a question like that on DIY.
Don't want the the roof caving in on you guys.


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## vsheetz (Sep 28, 2008)

If needed, perhaps something new (and more structually functional) could be put in place higher up on the rafters. This would free the area for conduit, etc. I'd consult an experienced framer - they would probably have other ideas as well.


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## Daniel Holzman (Mar 10, 2009)

A "collar tie" is typically a relatively small element, say 1x6, attached in the upper third of the attic. The purpose of a collar tie is to assist in transferring load from one side of the roof to the other (with respect to the ridge board) when uplift occurs, which typically occurs during high wind situations. A collar tie is not designed to replace floor joists, which have the function of resisting outward load on the walls caused by vertical roof loads due to dead load and snow. In fact, collar ties do not really even supplement floor joists in resisting outward thrust on the walls.

What you have are clearly not collar ties, since they are in the lower third of the attic. I am not sure what they are actually doing, possibly nothing. If you have a ridge board rather than a ridge beam (and I assume you have a ridge board), it is critical that the outward thrust generated by the roof against the walls be resisted by continuous floor joists that span from one wall to the other. It sounds like you are not sure if you have such a condition, since I gather from your posts that the floor joists are not continuous, but in fact there are two joists that may or may not be nailed together at the central support beam.

If your joists are not properly connected, the twisted "collar ties" may be absorbing some of the load that would normally be carried by the continuous floor joists. You definitely need to verify the connection detail of the floor joists prior to cutting the elements you refer to as collar ties.


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## scatkins (Sep 22, 2008)

GBR in WA said:


> 1. Measure the span of the rafter.
> 
> 2. Measure the size of the rafter.
> 
> ...


I'll get exacts, but this is approximate: 

1) Span of roof rafters is approx 28 feet (2 x 6)
2) Roof rafters are 2 x 6, ceiling rafters are 2 x 6.
3) Ceiling joists are nailed to every other rafter
4) The ridge (beam or board) looks to be a 4 x 4 (3 1/2 x 3 1/3), roof rafters do not sit on on top (like a beam) rather meet on side. Nailed no joist hangers. So I think this is a ridge board as opposed to a beam. However ridge board/beam is supported by by 2 x 4's down to load bearing interior walls every 8 to 10 feet.


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## scatkins (Sep 22, 2008)

jaros bros. said:


> Generally it is unlikely that they were placed there unnecessarily. You need to determine what is holding the walls from spreading outward from force exerted on it by the rafters. If the ceiling joists are doing this, they can be removed. If the ceiling joists are not continuous and tied in and working as a system, then they need to stay.


That has been my thoughts. My only thoughts were that maybe this was a common construction technique to hold the walls in place while the roof was framed. Doesn't sound to be the case though...


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## scatkins (Sep 22, 2008)

vsheetz said:


> If needed, perhaps something new (and more structually functional) could be put in place higher up on the rafters. This would free the area for conduit, etc. I'd consult an experienced framer - they would probably have other ideas as well.


Yes, this is my thought if they are indeed necessary. It sounds like any benefit of the ties is for tension to hold the walls from spreading outwords. 

Does anyone use steel cable? This would be the easiest way to accomplish this as opposed to long spans of lumber and getting it into an attic of an existing structure...


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## scatkins (Sep 22, 2008)

Daniel Holzman said:


> A "collar tie" is typically a relatively small element, say 1x6, attached in the upper third of the attic. The purpose of a collar tie is to assist in transferring load from one side of the roof to the other (with respect to the ridge board) when uplift occurs, which typically occurs during high wind situations. A collar tie is not designed to replace floor joists, which have the function of resisting outward load on the walls caused by vertical roof loads due to dead load and snow. In fact, collar ties do not really even supplement floor joists in resisting outward thrust on the walls.
> 
> What you have are clearly not collar ties, since they are in the lower third of the attic. I am not sure what they are actually doing, possibly nothing. If you have a ridge board rather than a ridge beam (and I assume you have a ridge board), it is critical that the outward thrust generated by the roof against the walls be resisted by continuous floor joists that span from one wall to the other. It sounds like you are not sure if you have such a condition, since I gather from your posts that the floor joists are not continuous, but in fact there are two joists that may or may not be nailed together at the central support beam.
> 
> If your joists are not properly connected, the twisted "collar ties" may be absorbing some of the load that would normally be carried by the continuous floor joists. You definitely need to verify the connection detail of the floor joists prior to cutting the elements you refer to as collar ties.


I get it. I need to make sure the ceiling joists are resisting the outward load. If they aren't continuous from outward walls, something needs to provide that tension...

THanks I'm getting the idea...


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## scatkins (Sep 22, 2008)

Thanks everyone, I think I got a little of the education that I was looking for on this subject.

This is what I have learned:

1) Sounds I need to make sure my outer walls don't spread from the roof load. 

2) If the ceiling joists provide this "tension" between the outer walls then I'm probably ok. If not, then I need something to provide that continuous link between. Maybe the ties were for that purpose originally .

In my case my ceiling joists probably partially accomplish this. For the most part there is a link but I need to verify this and possibly add some linkage (I'm currently remodeling and could easily do this)

3) In my case the ties defintely don't provide that any more (they are old and sagging), however maybe they should be repaired or replaced with something that does the job 

My final question is on ideas to replace the sagging boards?. One suggestion was to put ties higher up, that is an option, but it would still be a very long span (probably 30 feet) which will result in more sagging boards. 

How about a steel cable? This would be pretty easy to accomplish.


THanks for everyones input.

Steve..


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## jaros bros. (Jan 16, 2009)

IF the purpose is to resist outward thrust, you are limited to placing them in the bottom 1/3 of the rafter.


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## Daniel Holzman (Mar 10, 2009)

From your description, you may very well have a ridge beam. A ridge beam is a structural element that supports the rafters. This is completely different from a ridge board, which simply supplies a nailing surfact to nail the rafters to.

This is the structural difference. A ridge beam is supported in the vertical direction either by structural walls on the end, or in some cases by posts. In your case, it sounds like you have posts (2x4's) supporting the ridge beam every 8 feet or so. IF the ridge beam is adequately sized, and adequately supported, the rafters exert NO outward thrust on the walls. This is the advantage of a ridge beam versus a ridge board, a ridge beam completely eliminates the need for outward thrust resistance against the walls.

You still need to design to transfer uplift from one side of the ridge beam to the other, sometimes that resistance is supplied by the rafter connection detail to the ridge beam, other times by internal framing. IF you in fact have a properly designed ridge beam, then those horizontal "collar ties" were probably installed as temporary braces, and are no longer necessary.

The best way to tell exactly how your framing is working would be to hire an engineer or architect to examine your framing and give you a written opinion as to whether you can simply remove the "collar ties" and not replace them. This would entail performing calculations to see if the ridge beam is adequately sized, and whether the connection details are acceptable.


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## jaros bros. (Jan 16, 2009)

"The best way to tell exactly how your framing is working would be to hire an engineer or architect"

Any decent carpenter with skills could make that call as well, and I don't mean a weekend warrior. Even if there is a beam there, which it doesn't sound like there is based on the age of your place and the description, he could take the dimensions to the lumberyard and they could size everything for him through the engineers that work for their suppliers.


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## tpolk (Nov 7, 2009)

He said the ridge was 3-1/2" which does not cover the full height of the plumb cut on the rafters. Whether ridge is supported or not I feel additional wood needs to be added to the ridge to support the rafter face


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## scatkins (Sep 22, 2008)

tpolk said:


> He said the ridge was 3-1/2" which does not cover the full height of the plumb cut on the rafters. Whether ridge is supported or not I feel additional wood needs to be added to the ridge to support the rafter face


Sorry, just realized I mis-stated the ridge height. The rafters meet the ridge plumb, so the ridge height is 5 1/2".

But in reviewing the overall structure, I don't believe that the ridge is really being supported directly by the 2 x4's. The supports aren't all that "substantial" and appear to be more for stablization than as load bearing support. (they are 2x4 stock and sit on an interrior wall, however when you look at them they don't appear to be attached substantially at either the ridge or at the top of the load bearing wall directly below. It could be sloppy construction but it just doesn't look to be intended as a support). 

So, it would appear that the entire load is indeed sitting on the exterior walls of the house, which I think indicates the structural need somehow to keep the exterior walls from spreading. (either with a tie or through the ceiling joists).

I understand and will have someone take a look at this as well before I start cutting anything. I'm an engineer (not structural, but I do understand the static load concepts. It is the carpentry and framing techniques I'm trying to understand better).


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## Gary in WA (Mar 11, 2009)

I agree with Daniel, except for the reason why the rafter ties were installed. When framing a house with a stick built roof, you always install the ceiling joists on the walls first, to walk on when installing the rafters. I think the builders installed them thinking they were shortening the rafter span with collar ties- not really familiar with where or what they were for: ceiling joists *act as rafter ties* when installed* parallel* to rafters, otherwise rafter ties are required when ceiling joists run perpendicular to rafters. You don't need both in the same roof area.
I think they installed them thinking it would reduce your over-spanned 2x6 rafters.... 24"o.c. = 11'9" (no snow load) OR 16"o.c. = 14'1" n.s. I don't know the on center as you skipped my #4 question. Either way, with the 20-22' span (measured horizontally), I would add collar ties or purlins and struts to strengthen the roof system. Then remove the 1x4's. 

Page 39, rafter ties: http://books.google.com/books?id=iw...um=3#v=onepage&q=cutting floor joists&f=false

Page 257, collar ties- 1/2 way up, or purlins: http://books.google.com/books?id=1f...sult&resnum=1#v=onepage&q=collar ties&f=false

Be safe, Gary


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## scatkins (Sep 22, 2008)

GBR in WA said:


> I agree with Daniel, except for the reason why the rafter ties were installed. When framing a house with a stick built roof, you always install the ceiling joists on the walls first, to walk on when installing the rafters. I think the builders installed them thinking they were shortening the rafter span with collar ties- not really familiar with where or what they were for: ceiling joists *act as rafter ties* when installed* parallel* to rafters, otherwise rafter ties are required when ceiling joists run perpendicular to rafters. You don't need both in the same roof area.
> I think they installed them thinking it would reduce your over-spanned 2x6 rafters.... 24"o.c. = 11'9" (no snow load) OR 16"o.c. = 14'1" n.s. I don't know the on center as you skipped my #4 question. Either way, with the 20-22' span (measured horizontally), I would add collar ties or purlins and struts to strengthen the roof system. Then remove the 1x4's.
> 
> 
> ...


Oops, I did miss one of your questions..... The rafters are 24" OC. And independent of the ties I can see the need to strengthen the roof system as in looking at the rafter spanning tables the first thing I noticed is that they seemed to be undersized for the span. 

Strangely (or maybe lucky) enough the 50 year old roof seems not to have any signs of sagging or other bad structural things, however the actual roof loading looks to be pretty low and I'm in southern california so no snow or hurricanes. But I'm not sure what would happen if in the future someone changed the roof from composite to concrete tile. 

Going to look at the references and see what makes sense....


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## mrfixit38671 (Apr 13, 2010)

*collar tie*



scatkins said:


> Here is a simple cross section of the roof. THe red is the "collar tie" that I would like to remove.


 
thats not a collar tie...but a rafter tie instead


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