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Old 12-31-2009, 06:51 PM   #1
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Cutting rafter ties ??


Well not exactly.

Have a 50 year old 1 story house. Simple Roof construction, with a single ridge beam and roof rafters that extend from the ridge beam to the exterior load bearing walls.. Don't have the grade of roof but it isn't overly steep (easily walked on without siding off).

Question:
There are what I can best describe as "collar ties" which run every other rafter. However these ties are really low on the roof and connect to the roof rafters just above the exterior walls. In fact the collar ties are so long that they sag and lay on the ceiling rafters. (Actually the ties are two long ~20 foot 1 x 4's that are nailed together to extend about 40 feet.

I'm remodeling and would like to remove these ties since they are sagging and make it difficult to run conduit and other stuff in the attic. I don't think they are accomplishing anything structural (since they are sagging so bad they don't apply any compression or tension). I know what collar ties do, but these don't seem to be for that function. Most I have seen are on steeper roofs and towards the top of the roof not the bottom.

I'm thinking these are maybe remnants of the original construction process that were holding things together while the roof was being framed. But, I'm always a little nervious about cutting things. I'll post a diagram as well.

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Old 12-31-2009, 07:01 PM   #2
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Cutting rafter ties ??


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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Old 12-31-2009, 07:04 PM   #3
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Cutting rafter ties ??


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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Old 12-31-2009, 07:07 PM   #4
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Cutting rafter ties ??


I understand that part, need help with the other parts
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Old 12-31-2009, 07:11 PM   #5
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Cutting rafter ties ??


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Originally Posted by tpolk View Post
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..

Last edited by scatkins; 12-31-2009 at 07:18 PM.
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Old 12-31-2009, 07:12 PM   #6
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Cutting rafter ties ??


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Originally Posted by tpolk View Post
I understand that part, need help with the other parts
Sorry, you were quicker than I was, was still composing.....
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Old 12-31-2009, 09:25 PM   #7
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Cutting rafter ties ??


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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Old 12-31-2009, 10:08 PM   #8
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Cutting rafter ties ??


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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Old 01-01-2010, 06:51 AM   #9
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Cutting rafter ties ??


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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Old 01-01-2010, 09:47 AM   #10
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Cutting rafter ties ??


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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Old 01-01-2010, 11:24 AM   #11
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Cutting rafter ties ??


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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Old 01-01-2010, 11:50 AM   #12
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Cutting rafter ties ??


Quote:
Originally Posted by GBR in WA View Post
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
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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Old 01-01-2010, 11:52 AM   #13
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Cutting rafter ties ??


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Originally Posted by jaros bros. View Post
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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Old 01-01-2010, 11:54 AM   #14
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Cutting rafter ties ??


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Originally Posted by vsheetz View Post
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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Old 01-01-2010, 11:57 AM   #15
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Cutting rafter ties ??


Quote:
Originally Posted by Daniel Holzman View Post
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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