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Discussion Starter · #1 · (Edited)
HELP!? I have a modular ranch built here in NE PA in 2007. The ranch came with a full set of steps to an unfinished attic. With the family expanding, we wanted to explore options for making this attic space livable. I'm fully confident I can finish off the space myself, but I'm most concerned about structure; specifically, the roof rafters and collar ties. I'm going to try my best to include pics so you can see. The collar ties are too low for me as they are about 6'10" off the floor space. I would love to move them up and at least get a 7.5ft ceiling. Since this was a modular and assembled as two halves on site, they did some pretty funky things with the rafters. They set up the 2x6 rafters on 24in centers, but they didn't carry them up to the ridge. (see pics). The rafters stop at the collar ties, then they use 2x4 above to carry up to the ridge. I'm fairly confident I CANNOT remove the collar ties and move them up as they would not properly tie into the rafters, but could I sister in additional 2x6 to the existing 2x6 rafters and carry them up to the ridge? Looking at this pics, does that seem feasible?? Are there any alternative options I should consider? Again, I want to move the ties up, insulate and finish off the space. Thanks in advance for your help with this.

Links for pics:
https://drive.google.com/open?id=0BzHemI3wU70XSkxZMTFCUWt1czA
https://drive.google.com/open?id=0BzHemI3wU70XOEVGOXRoNmJUVEE
https://drive.google.com/open?id=0BzHemI3wU70XUGdadEVxZ29XVnc
 

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Be aware that some "modulars" have a two part roof system where the top section is hinged, is stowed in a lower position for transportation, and is raised into final position once the sections are in place on the foundation.
In that case, you would not be moving these collar ties.
 

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Discussion Starter · #3 ·
Be aware that some "modulars" have a two part roof system where the top section is hinged, is stowed in a lower position for transportation, and is raised into final position once the sections are in place on the foundation.
In that case, you would not be moving these collar ties.
Thanks for the response. This may have been the case where the top is hinged. Not sure. Why couldn't I just run 2x6 up to the peak and sister them into the existing 2x6? I've had a few general contractors out that seem to think that would be feasible? No?
 

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I am not a Lawyer, but you would risk voiding any Manufacturer's Warranty, I would think.

Also, are those ceiling joists rated to be used as a floor?
 

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Discussion Starter · #5 ·
According to the person I spoke to at Pennwest, the attic space was intended to be finished living space. The roof is 9/12, the steps going up are finished and the attic has two full sized 36in windows at either end. From what I can see the engineered trusses in the floor are 24in OC. The runs are short (less than 14ft) because they sit on a marriage wall. The builder finished the floor with half inch, so that needs to be reinforced a bit. I was planning on getting that structure stuff approved by the township. The rest of the space I can finish out on my own at my own pace.
 

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As to modifying the roof structure, speak with your local building inspector or possibly a structural engineer.
I would have to agree. You are modifying a major structural element and will need to get a engineer or the city building department to sign off on your plan, especially because you are dealing with a modular home which was specially engineer to begin with, which means that no one here can give you a "prescriptive" building solution.

Also as said you will void any warranty.
 

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Interesting framing, I have not seen it before. Your "collar ties" are doing a lot more than the normal collar tie. A collar tie is typically a lightweight horizontal element used to connect opposite rafters. The purpose of a collar tie is to equalize roof uplift during high wind events. The collar tie is not normally intended to carry any load under normal conditions, is usually a 1x4 or similar sized element, and is normally attached to every third rafter. The collar tie is generally installed about 2/3 of the way up between the floor and the peak of the roof.

Your "collar ties" are holding up the rafters above them, which is certainly unusual. Even if you replaced the rafters, or sistered in a full dimension extension to the peak, your local building code may require collar ties in the 2/3 up position, only your building inspector can tell you. Raising the collar ties diminishes their usefulness in resisting wind uplift, so you need to understand the whole program before you do anything. This is an odd situation, you may need to call the home manufacturer, an engineer, or an architect for advice.
 

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I don't think it's going to be easy. It looks like the 2x6 part is separate from 2x4 part. If you look at the 2x6 roof as a flat roof - the collar ties are actually flat rafters - and lighter 2x4 pitch added to finish the roof as a gable, then you can't move the collar ties because they are actually rafters. Moving them would mean completely reframing the roof. Maybe the house was built when 6.5 ceiling was legal.
The existing rafters also don't give you enough depth for useful insulation. Even if you use spray foam, ventilation is a must. Check Buildingsciences site for moisture damaged roof deck that was supposed to be draft/moisture proof.
BTW, keep the collar ties and sheetrock above it? Custom steel reinforcement for 2x joint and new collar ties? Maybe possible but these are questions for the engineer. Can the manufacturer answer these for you?
 

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Discussion Starter · #10 ·
I don't think it's going to be easy. It looks like the 2x6 part is separate from 2x4 part. If you look at the 2x6 roof as a flat roof - the collar ties are actually flat rafters - and lighter 2x4 pitch added to finish the roof as a gable, then you can't move the collar ties because they are actually rafters. Moving them would mean completely reframing the roof. Maybe the house was built when 6.5 ceiling was legal.
The existing rafters also don't give you enough depth for useful insulation. Even if you use spray foam, ventilation is a must. Check Buildingsciences site for moisture damaged roof deck that was supposed to be draft/moisture proof.
BTW, keep the collar ties and sheetrock above it? Custom steel reinforcement for 2x joint and new collar ties? Maybe possible but these are questions for the engineer. Can the manufacturer answer these for you?
Great feedback. Thank you. I think you've hit it on the head. I think the 2x6 are aligned as a flat roof, which to me is the most ridiculous move made to save a buck, as it puts the headroom close to 6'8 or 6'10" The attic space has a large 28ft laminated beam that pokes out from the center of the floor. I know it's it's to carry the load of the open space on the first floor and it can't be moved. On either side of the attic space are the windows and spots I'd like to make rooms. I'm wondering if I could keep costs down by only reframing the outer third section on either end of the roof, keeping the center space at the current configuration and using that as unfinished storage? It sounds like the only way I'll get more headroom is to reframe the roof. That alone may price is out of the game entirely, but if there was a way to save money by only reframing the space we intend to finish, maybe that's the way to go. As far are your points about insulation and venting, wouldn't a 2x6 afford enough room for insulation while maintaining a vertical vent out the ridge?
 

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Insulation requirement has been going up. R30 then r40 now, I think. Some people want 60. There is a point where more insulation does not mean more insulating value, but 60 seems to please good building people. But the point here, is that closed cell foam is the most efficient but it is still about r5 per inch. Foam is great with stopping the draft but it is not a miracle insulation. If you have a roof that is insulated differently in spots, you can get ice dams in the middle of the roof. I don't think you want that, esp your roof framing with 2x4 lumber and joints. There is less structurally so you don't want any to be damaged.
 

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Hi jl, I've been pondering what could be done with a minimum effort and expense. The double 2x6 at the top of the 2x6 rafters is acting as a header keeping the roof flat and joining all rafters together. That means the collar ties are working in total and not individually. Remove one and that rafter would still be supported by the header. Remember, I'm just thumb buster and not an engineer.

But, if my thinking could hold up under the educated eyes of an engineer, I think you could move the collar ties to above that header, maybe one at a time. Located above it could still be securely attached to the header and it is the header that is supporting all of the rafters. An engineer might give this a blessing at a very reasonable price.

If that were to be approved, then you would still need to decide on how much insulation and if or how to ventilate those rafters. That double 2x6 is right in the way of a clear air path. You might want to read up on an unvented roof assembly. That would allow you to utilize the full space for insulation and get closer to whatever is required for your location.

Bud
 

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I think I addressed the above to jl and it should have bee Irish. Lack of sleep mybad.

Bud
 

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Discussion Starter · #14 ·
Hi jl, I've been pondering what could be done with a minimum effort and expense. The double 2x6 at the top of the 2x6 rafters is acting as a header keeping the roof flat and joining all rafters together. That means the collar ties are working in total and not individually. Remove one and that rafter would still be supported by the header. Remember, I'm just thumb buster and not an engineer.

But, if my thinking could hold up under the educated eyes of an engineer, I think you could move the collar ties to above that header, maybe one at a time. Located above it could still be securely attached to the header and it is the header that is supporting all of the rafters. An engineer might give this a blessing at a very reasonable price.

If that were to be approved, then you would still need to decide on how much insulation and if or how to ventilate those rafters. That double 2x6 is right in the way of a clear air path. You might want to read up on an unvented roof assembly. That would allow you to utilize the full space for insulation and get closer to whatever is required for your location.

Bud
Bud,
Thanks for putting some thought into this one! I appreciate that. I think the issue with moving the collar ties is that for all intents and purposes, they are the structural rooftop. The 2x6 stop at that collar tie. Are you suggesting running 2x6 up to the top of the ridge and then moving the collar tie up? That was what I'm hoping I can get approved. I would love to just sister one next to the existing 2x6, but even if I can't do that, I don't know why I couldn't just run new 2x6 or 2x8 (whatever they want) from the top plate up the ridge? We should be able to do that with the roof in place.
 

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First a couple of questions. One, I assume the collar ties attach to rafters on both sides in a similar fashion? Two, is that actually a double 2x6 with a 2x2 on the inside acting as a spacer to align the 2x4's that continue up as rafters? I'll assume yes to both.

Then, you said "The 2x6 (rafters) stop at that collar tie." If I'm seeing it correctly, they stops at the double 2x6 top plate at the top edge of the collar ties.

Here's my point. Those are not normal collar ties. Normal would be tying rafters on one side to the rafters on the other. Yes, they are in that position, however the presence of the double top plate (acting as a header or strongback) TOTALLY changes the function of those collar ties. Now they are tying the two assemblies together formed by the rafters with a header on top on each side. If you relocated those collar ties to directly above their current location they would still be supporting side to side. I do think an engineer would take the header function of the double top plate into consideration and most likely allow you to relocate them.

Consider, if you create a triangle out of the framing above the current collar tie location and secure it to the top of the double top plate it would be just as strong as what is there now.

I realize my explanation is clear as mud, but that is where an engineer needs to come in. s/he can sketch something up and put a stamp on it and everyone will be happy.

Bud
 

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Discussion Starter · #16 ·
Yes, the collar ties attach to each side in the same fashion. They cross every two feet. The 2x6 are not doubled at all. A single 2x6 comes up from the top plate to the top of the collar ties. The rafters run every 2ft. Above the collar tie sits 3 2x4s stacked horizontally. On top of them is a single 2x4 that goes up to the ridge. The 2x4 work is sloppy. In some spots it almost looks like the 2x4 up to the ridge is not even nailed into the horizontally stacked 2x4s that are above the collar tie.
 

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Yes, that is exactly what I was seeing. In my opinion, it doesn't matter whether you secure that double top plate, side to side, from below as it is or from above. And creating a triangle that is securely fastened to the top of those two 2x6's is as good as it gets. A triangle is one of the strongest structures.

Bud
 
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