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Old 01-29-2017, 03:00 AM  
Cooter85
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Default Sagging Roof on Shop

I have a 24 x 40' shop with a bonus room upstairs. The roof is sagging in the middle, and one of the walls is bulging outwards. It has 2x10 rafters nailed to a ridgeboard 24" OC, and notched and nailed at the wall plates (2x6 walls). The collar ties are 2x8's, on every other rafter, and no ceiling joists, as the walls are 4' high in the upstairs room. The home was built in 1978, all lumber is nailed, no ties or mending plates or anything.

The bottom ends of the rafters are pulled away from the ridgeboard about 1.5" at the worst in the middle. And they have slid off the wall plate a few inches as well .

I tried lifting the ridge with a bottle jack and got it level, but the rafters need to be pulled in. How can I do this?

My understanding is that without ceiling joists, there is nothing holding the bottom of the roof from spreading outwards from downward force, but putting joists on top of the walls would be right at chest level in the room. So could I reinforce the roof enough with other methods to not need joists at the wall plate?

I'd appreciate any advice. To a new homeowner trying to finish a man cave.


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Old 01-29-2017, 06:56 AM  
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Sounds like your going to need a load carrying ridge beam, or some posts in the room.
I would go with the ridge beam, probably a laminated product. And you will need a way to get it into place because it will be one piece..or you will have posts.

An engineer can point you in the right direction for a few hundred bucks. Call around.


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Old 01-29-2017, 07:19 AM  
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with inspector, hire an engineer to write a scope of work. Lots of moving parts should failure occur during a repair if not done right.
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Old 01-29-2017, 10:08 AM  
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First off I’m not a builder or a professional in any building trade so take my advice or suggestions as coming from a homeowner handyman such as yourself. The smart side of me is going to give you the smart advice you were given above. It also wont be a cheap date and most likely wont be a DIY fix. It will require most likely a crane, and going down thru the structure with support columns and into footings capable of carrying half the roof load both structure and snow etc. Windows and such will be involved.

It looks like you are closing it in and discovered the problem. Drywall is going to add even more weight to a structure that could be close to failure.

Now as the homeowner handy man it looks to me like it was just built by someone that thought they knew what they were doing with the collar ties and heavy rafters and trying to make a bonus area out of the space that new construction would be wasted and all trusses. The collar ties are part of the problem but IMO the method of construction of just nailing is the biggest problem. It looks to me almost the building was a homeowner built project or built by a guy with a 4’ level hanging on the easy rider rifle rack in the back window of his pickup truck. It was never a structure that numbers were run on. Sometimes I say just stabilize a structure that has some problems, but with your knee wall bowing out and a drop in the roof line I say you are past that point. Your roof needs to be brought back into location then stabilized to keep it there.

One question I have is the knee wall I just mentioned. Is that wall a short wall built on top of the floor and wall below it. Or is it balloon framed and an extension of the studs in the wall below? I think that is an important question for starters. As a short knee wall built on top and nailed down is a hinge point and offers little inward pull to resist spreading and the floor ceiling joists are not at all working with the collar ties to prevent spreading.

I had a bunch of similar problems with the owner built garage that came with the short sale house we bought a couple years ago. Mine was much worse construction than yours and built by the owner from whatever scrap lumber he came across over many years. I had a builder come look at it and the advice was tear it down and start over. Both of them were not an option at that time and I took it on myself to correct and then over structure the stabilization. He stopped over after and said well it isn’t pretty but it should stand 100 years.

I’m not encouraging you to get in over your head and we have no ideas what your background is and your skill levels are. Even as a DIY attempt it might cost a fair amount of money but I feel could be pulled back and fixed in a strong safe manner. I would start though by taking down just about everything you have done so far and get the roof problem fixed first.
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Old 01-29-2017, 02:36 PM  
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Sorry, that is an older pic of the room. The last owner was putting 1/4" plywood walls and ceiling. I have since torn all the plywood off, and removed enough insulation to access what I need.

My plan was to straighten everything up, then put strong ties at the ridge and wall, and double the joists. I am not opposed to the idea of posts, or even building a wall in the middle of the room for load bearing.

My problem right now is how to pull the rafters inward to sit flush on both sides. Should I start from one end of the room and do one at a time, or use 3 or 4 come-alongs to pull them all at once? How do I attach the chain/cable/rope to the rafter? Drill a hole and slip a shackle through each one? Or go through the fascia and hook onto a steel bar outside to pull them all in? Lol
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Old 01-29-2017, 09:56 PM  
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Rafter ties or ceiling joists should be in the lower third of the height from the wall to the peak.
Measured straight up or on the angle the answer should be the same.

You show the birds mouth cut out to sit on the wall, compare that cut out to the one on the gable end. there is no guarantee that it was ever up tight.
Measure the width between wall at each end and in the middle, There are tricks to fixing this.

Before you finish insulating, lets talk about venting.
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Old 01-29-2017, 10:53 PM  
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Just another homeowner chiming in, but FWIW, shouldn't the joists between the first & second floor be doing some of that wall support? Do we know whether the joists are running in the right direction and are securely fastened to the walls? Any sign of movement from them, as they should show a gap also?
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Old 01-29-2017, 11:01 PM  
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Quote:
Originally Posted by slownsteady View Post
Just another homeowner chiming in, but FWIW, shouldn't the joists between the first & second floor be doing some of that wall support? Do we know whether the joists are running in the right direction and are securely fastened to the walls? Any sign of movement from them, as they should show a gap also?
Yes, I think he got his measurement by the look of the birds mouth and actual spread will be much less.
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Old 01-30-2017, 05:51 AM  
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Quote:
Originally Posted by slownsteady View Post
Just another homeowner chiming in, but FWIW, shouldn't the joists between the first & second floor be doing some of that wall support? Do we know whether the joists are running in the right direction and are securely fastened to the walls? Any sign of movement from them, as they should show a gap also?
Thatís why I asked the question if the knee wall was an extension of the first-floor wall as a type of balloon framing or if it is a short wall attached to the deck like modern construction supporting a truss would be done. (still unanswered) The joists below play no role if the short wall can hinge on a row of nails.

Framing must be looked at as a mechanics problem and the forces and angles work together. As an example, the lower the pitch the greater the tension in the collar tie. The higher the collar tie the greater the tension. In a truss, all the members for the most part are in compression and tension. A rafter and collar tie or just rafters and joists are the simplest of truss. Once the forces exceed the strength of the fastening system movement happens.

The OP is asking questions no one knows the answer to yet. In general to answer his last question I think they would all have to be pulled back at once. As doing anything in part the rest of the structure would be resisting and thatís when things start breaking. His effort to jack the ridge back up didnít work because he didnít have a horizontal force component to his plan.
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Old 01-30-2017, 02:14 PM  
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Quote:
Originally Posted by bud16415 View Post
Thatís why I asked the question if the knee wall was an extension of the first-floor wall as a type of balloon framing or if it is a short wall attached to the deck like modern construction supporting a truss would be done. (still unanswered) The joists below play no role if the short wall can hinge on a row of nails.

Framing must be looked at as a mechanics problem and the forces and angles work together. As an example, the lower the pitch the greater the tension in the collar tie. The higher the collar tie the greater the tension. In a truss, all the members for the most part are in compression and tension. A rafter and collar tie or just rafters and joists are the simplest of truss. Once the forces exceed the strength of the fastening system movement happens.

The OP is asking questions no one knows the answer to yet. In general to answer his last question I think they would all have to be pulled back at once. As doing anything in part the rest of the structure would be resisting and thatís when things start breaking. His effort to jack the ridge back up didnít work because he didnít have a horizontal force component to his plan.
We hope it is balloon framed,the floor would be holding the roof.
But if it is then the floor upstairs comes into question, if the joists are just nailed to the side of studs, jacking the roof from that floor could cause a whole world of trouble.
So I agree we need much more info about the structure before making suggestions.


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