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Old 03-02-2008, 11:17 AM   #1
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Barn Gambrel w/no collar ties--sag and sep


the original owner of this house built a 20 by 30 shop/barn with a gambrel roof. the entire shop is stick built, and the upper floor has developed a bit of a problem.

as far as i can tell, the outside stud walls are being pulled apart vertically where the upper slope rise meets the lower slope rise. this has manifested itself by a one-plus inch gap appearing between the floor plate on both sides of the building. the walls also appear to be leaning slightly.

after looking at a few books, i have arrived at the conclusion that since there are no collar ties, the gambrels have slouched and pulled the stud wall apart.

can this be fixed or repaired? i'll add some pictures as soon as the light gets a little better.
Attached Thumbnails
Barn Gambrel w/no collar ties--sag and sep-studwall.jpg   Barn Gambrel w/no collar ties--sag and sep-studwalldetail2.jpg   Barn Gambrel w/no collar ties--sag and sep-studwalldetail.jpg   Barn Gambrel w/no collar ties--sag and sep-upperdeck.jpg  


Last edited by densmore; 03-02-2008 at 12:16 PM. Reason: add photos
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Old 03-02-2008, 09:02 PM   #2
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Barn Gambrel w/no collar ties--sag and sep


My structure we used tongue and groove 3/4 inch plywood all glued together and metal plates screwed in making sure that this single plywood plane could withstand the outward forces of the roof not only pushing down but also pushing out. We also found a top shelf structural engineer who is a bit of a renegade to do the math and put his license on our plan.

So to answer your question, sure it can be fixed. But more importantly you had better find some time to take some long hard looks with a level and tape and maybe a plumb bob or laser and get some specific measurements, and understand what is going on on that gambrel roof design. Obviously those studs shifting should not be doing that. And you want to fix and not bandage.

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Old 03-03-2008, 01:54 PM   #3
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Barn Gambrel w/no collar ties--sag and sep


I don't see any fasteners in the wall studs. If the ridge beam was dropping down I would expect shifting where the wall studs hit the roof joists. The bottom of the stud where it hits the bottom plate would be tilted out towards the gambrel.
Temporarily, I would run a stud wall down the center under the ridge beam so it doesn't drop anymore.
If you have the time now, jack up the ridge beam so the stud wall sits where it should and install rafter ties on every third roof rafter.
This is not a straight forward task. You need to provide lateral support to hold the sides in place while you crank this structure back in place. If you're unsure about the loads and support, call someone in who can do the job without injury.
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Old 03-03-2008, 03:28 PM   #4
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Barn Gambrel w/no collar ties--sag and sep


what size are the floor joists? they are 20' clear span? It could be that the floor is deflecting that much and the roof framing,along with the knee wall are staying in place.
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Old 03-03-2008, 03:36 PM   #5
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Barn Gambrel w/no collar ties--sag and sep


You could consider running some cable from top plate to top plate with a turnbuckle and gradually crank the walls back into plumb. you'd need to do several runs and pull it back over a period of time. It didn't sag in a few days and it will take some time to pull it back. I once pulled a sagging garage roof back using that method. Once it was back where it belonged, I left the cables in place as permanent support. It looks like you may not have the head clearance for that. After you have the stud walls back down where they belong you could plate them with some 3/4 plywood screwed to the studs and bottom plate and screw or lag the bottom plate down to the joists below or add collar ties. Personally, I'd be inclined to do both. It looks like the studs weren't nailed to the bottm plate very well. At this point I don't think jacking up the ridge will pull the walls back into plumb, but it could make pulling them back with the cables quicker and easier. The key to these types of repairs is to go slowwwwwwly and evenly.
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Old 03-03-2008, 03:38 PM   #6
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Barn Gambrel w/no collar ties--sag and sep


Quote:
Originally Posted by johnrem View Post
what size are the floor joists? they are 20' clear span? It could be that the floor is deflecting that much and the roof framing,along with the knee wall are staying in place.
That's a good thought too. I'd be for checking everthing before you go jerking and jacking.
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Old 03-03-2008, 05:49 PM   #7
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Barn Gambrel w/no collar ties--sag and sep


I can't see one nail in any of the wall studs !!
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Old 03-04-2008, 01:36 AM   #8
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Barn Gambrel w/no collar ties--sag and sep


hey thanks to everyone who has replied, i really appreciate it.

1. the floor joist run to a center beam that is mid-span on the first floor. the floor on the upper deck isn't deflecting (noticeably).

2. there are nails in the stud walls. they were built flat and put up as you'd expect but my photos are a bit weak in showing that.

I think the big problem is that the whole roof/rafter part of the barn has zero collar ties. I may try to just pull them back into place and add them.

One thing i did notice is that the ridge beam is 1x? and is deflected.

Could I use a screw-jack to lift this back in place before pulling the stud-walls back to plumb?

thanks gain.
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Old 03-04-2008, 06:16 AM   #9
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Barn Gambrel w/no collar ties--sag and sep


I would be inclined to do both at once. Lift the ridge AND pull the knee walls in. I'd be afraid that jacking the ridge alone would pull things apart somewhere else. A screw jack is certainly the way to go. Since you only have a one by for a ridge board, I'd laminate a couple of 2x4s together and jack over several rafters at the same time. If you can get more than one screw jack, do a couple of places at the same time. Keep alternating between the jacks and pulls on the knee walls, nudging them a little at a time.

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