Sagging Roof on Shop

Discussion in 'Framing and Foundation' started by Cooter85, Jan 29, 2017.

Help Support House Repair Talk by donating using the link above.
  1. Jan 29, 2017 #1

    Cooter85

    Cooter85

    Cooter85

    Member

    Joined:
    Jan 29, 2017
    Messages:
    8
    Likes Received:
    0
    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. :)

    20170122_124833.jpg

    20170122_124718.jpg

    20170128_163917.jpg
     
  2. Jan 29, 2017 #2

    inspectorD

    inspectorD

    inspectorD

    Housebroken Staff Member Admin Moderator

    Joined:
    Dec 17, 2005
    Messages:
    4,503
    Likes Received:
    267
    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.
     
    Last edited: Jan 31, 2017
  3. Jan 29, 2017 #3

    oldognewtrick

    oldognewtrick

    oldognewtrick

    Administrator Staff Member Admin Moderator

    Joined:
    Jul 26, 2009
    Messages:
    10,839
    Likes Received:
    1,445
    :agree: 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.
     
  4. Jan 29, 2017 #4

    bud16415

    bud16415

    bud16415

    Fixer Upper Staff Member Admin Moderator

    Joined:
    Feb 5, 2013
    Messages:
    4,715
    Likes Received:
    1,623
    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.
     
  5. Jan 29, 2017 #5

    Cooter85

    Cooter85

    Cooter85

    Member

    Joined:
    Jan 29, 2017
    Messages:
    8
    Likes Received:
    0
    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
     
  6. Jan 30, 2017 #6

    nealtw

    nealtw

    nealtw

    Contractor retired

    Joined:
    Nov 4, 2010
    Messages:
    23,974
    Likes Received:
    3,145
    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.
     
  7. Jan 30, 2017 #7

    slownsteady

    slownsteady

    slownsteady

    Administrator Staff Member Admin Moderator

    Joined:
    Jun 6, 2009
    Messages:
    6,575
    Likes Received:
    1,187
    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?
     
  8. Jan 30, 2017 #8

    nealtw

    nealtw

    nealtw

    Contractor retired

    Joined:
    Nov 4, 2010
    Messages:
    23,974
    Likes Received:
    3,145
    Yes, I think he got his measurement by the look of the birds mouth and actual spread will be much less.
     
  9. Jan 30, 2017 #9

    bud16415

    bud16415

    bud16415

    Fixer Upper Staff Member Admin Moderator

    Joined:
    Feb 5, 2013
    Messages:
    4,715
    Likes Received:
    1,623
    That’s 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 that’s when things start breaking. His effort to jack the ridge back up didn’t work because he didn’t have a horizontal force component to his plan.
     
    nealtw likes this.
  10. Jan 30, 2017 #10

    nealtw

    nealtw

    nealtw

    Contractor retired

    Joined:
    Nov 4, 2010
    Messages:
    23,974
    Likes Received:
    3,145
    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.
     
    bud16415 likes this.
  11. Jan 30, 2017 #11

    bud16415

    bud16415

    bud16415

    Fixer Upper Staff Member Admin Moderator

    Joined:
    Feb 5, 2013
    Messages:
    4,715
    Likes Received:
    1,623
    We don’t know what we don’t know. My guess is it is built just like you would frame a two story house only the second story walls are only 4’ high. Good construction practice would put the first floor studs directly under the second floor studs and the rafters directly over them. that doesn’t provide much strength for pushing that short wall out though.
     
  12. Jan 30, 2017 #12

    nealtw

    nealtw

    nealtw

    Contractor retired

    Joined:
    Nov 4, 2010
    Messages:
    23,974
    Likes Received:
    3,145
    There is a fix for either way it is built, I just want to know how bad it is before getting into it.
     
  13. Jan 30, 2017 #13

    Gary

    Gary

    Gary

    Well-Known Member

    Joined:
    Oct 3, 2005
    Messages:
    453
    Likes Received:
    297
    I'm also just an amateur carpenter. I was employed by a general contractor building houses in my younger days, so that's where my experience comes from.
    If it were mine, and this may be overkill, but that's what I tend to do. I would run cable from the outside wall through the building and out the opposing side. Maybe one in the center would be enough. If not, use as many as needed to support the walls with somewhat even pressure. Maybe ready rod through the walls tied to the cable. Run the ready rod through steel plates on the outside or even timbers to distribute the load. then tighten up nuts on the ready rod until you have tension on the cable (s). At best you may be able to draw the bow out of the walls by tightening the ready rod bolts. If that doesn't work at least you'd have some back up support while figuring out a plan of action.
    I'm going on the assumtion that the structure may not be stable? This would at least provide some temporary stability, making it a little safer to work on.
     
    Last edited: Jan 30, 2017
  14. Jan 30, 2017 #14

    nealtw

    nealtw

    nealtw

    Contractor retired

    Joined:
    Nov 4, 2010
    Messages:
    23,974
    Likes Received:
    3,145
    You would pull it in before you knew how far you want to pull it.

    If the OP is correct about it being out 1 1/2 inches and he shows that maybe the rafter has slipped out from the wall. Then the roof has moved with out the wall. If the walls are short knee walls on the platform, you may just have pulled wall out from under the roof.

    You just don't have enough info to make suggestions here.
     
  15. Jan 30, 2017 #15

    Gary

    Gary

    Gary

    Well-Known Member

    Joined:
    Oct 3, 2005
    Messages:
    453
    Likes Received:
    297
    My main thought was just tension, on the walls, at least at first, not moving anything. At least that way there would be some measure of safety if the building is unstable. If the roof is slipping off the top plate, then support under the ridge pole. I guess what I'm saying is be darn sure it's supported well before work starts.
    But you are right, more info is needed to know for sure what is and isn't needed. More pics at least. Someone with experience on site to inspect would be the best solution if only for advise. If he's unsure at all, this probably isn't a good DIY project. Things could go south in a hurry.
     
    Last edited: Jan 31, 2017
  16. Jan 31, 2017 #16

    Cooter85

    Cooter85

    Cooter85

    Member

    Joined:
    Jan 29, 2017
    Messages:
    8
    Likes Received:
    0
    It is not balloon framed. The upstairs walls are nailed to the floor. The floor joists run perpendicular to the direction of the roof rafters. They are 2x6s, 24" OC, and they rest on 8" beams in the walls, and one big 8x24 timber in the middle (my car engine hanger. :) )

    The birdsmouths are nearly flush against the wall plate on either end, and gets progressively worse towards the center. Same goes with the rafter contact with the ridgeboard.

    My best guess is to start on the ends and pull one or two at a time, working toward the middle until everything comes together. My concerns are where and how to hook on to pull. Also, each board has 4-6 nails in it, and I would probably need to cut them loose or else risk pulling the knee wall in too far.

    20170129_165448.jpg
     
    Last edited: Jan 31, 2017
  17. Jan 31, 2017 #17

    bud16415

    bud16415

    bud16415

    Fixer Upper Staff Member Admin Moderator

    Joined:
    Feb 5, 2013
    Messages:
    4,715
    Likes Received:
    1,623
    Thanks for the information.

    Right now the only thing that is holding your building together is the collar ties and the only thing holding them is a handful of nails. The problem as you would expect is worse in the middle as the ends are gaining strength from the end walls below. The information that the floor joists are running the long way in the building is also not good news IMO.

    You are correct the nails will fight you with trying to pull things back as will all the sheathing attached to all the other rafters that you don’t plan to pull on. As I mentioned above the collar ties are taking it all and for movement to have happened the nails attaching the collar tie to the rafter had to start to twist. It is like a house of cards right now. You haven’t mentioned where you live and if there is the likelihood of a bunch of snow loading the roof in the next month or so?

    I still go with the first impression of the two experts here that bringing in a pro would be a good idea. I also know you have some abilities and desire to get this fixed yourself. Personally I would go back and do something very much like our member Gary suggested and make some attempt to stabilize what you have for now.

    Here are some ideas and only ideas and thoughts at this point. Assuming it was all framed dimensionally correct in the first place what has happened is the drop in the ridge is with doing the trig is equal to the spread in the walls. Things are kind of toggle-ing around points that want to rotate, base of the knee wall, connection of the collar ties and the ridge.

    You are going to need more collar ties at that height at least one for each pair of rafters and better one on each side of each rafter. I would be tempted to put those in first even if they had to be removed and done again after you pull the walls in. if they were attached with a single bolt .50 dia and washers and nuts they could take load and still can rotate during the correction. Oversize holes spaced in the right direction would be needed as the span of the collar tie will lessen when it goes up. That could be calculated. I would then cable the bottom of every other set of rafters. Strap come-along’s or cables with turn buckles etc. and snug it all up. At that point you could remove the old collar ties one at a time by sawing off the nails and replacing them like you did the new ones. Once I had the roof safely stabilized and freedom to move I would place 3 or 4 jacks against the ridge like you have and slowly pull all the bottoms in a little at a time and work the jacks up a little at a time.

    The roof didn’t start to fail one rafter at a time it slid out as one big heavy piece and IMO to bring it back it has to come back as one piece.

    The only other way I could think of fixing it would be wait for good weather and remove the whole roof and rebuild it from scratch.
    Again I’m not a pro and the above are just ideas to be taken with a grain of salt.
     
    Last edited: Jan 31, 2017
  18. Jan 31, 2017 #18

    nealtw

    nealtw

    nealtw

    Contractor retired

    Joined:
    Nov 4, 2010
    Messages:
    23,974
    Likes Received:
    3,145
    This is the kind of job where we would bring in the engineer, the owner, all the employees and anyone else that was interested.
    And kick around ideas until we talked about every sound or silly idea until a plan was developed.

    Bud talked about the weight, that is killer, then there are jacking points. Jacking in the center could blow the peak apart..

    If the sag in the roof is acceptable, making it stable where it is would be a good option.

    Are the knee walls still plumb or are they leaning out?
     
  19. Jan 31, 2017 #19

    bud16415

    bud16415

    bud16415

    Fixer Upper Staff Member Admin Moderator

    Joined:
    Feb 5, 2013
    Messages:
    4,715
    Likes Received:
    1,623
    My understanding Neal is they are leaning 1.5” in the center and tapering better near the ends. 1.5” IMO is too much.

    As to the jacking I suggested that should only be done after the bottom is cabled tight and then even it shouldn’t be the main force resetting the roof it should just follow along taking some of the weight.

    I think a heavy snow load or strong winds could be the tipping point. I wouldn’t want to be up there when the knee walls kick out. When they go they are going all at once. Add up the weight of all that lumber and count the nails in those collars. I would be putting a pin / bolt thru every one of them first thing.
     
  20. Jan 31, 2017 #20

    Cooter85

    Cooter85

    Cooter85

    Member

    Joined:
    Jan 29, 2017
    Messages:
    8
    Likes Received:
    0
    I live in Oregon, we get a bit of snow once in awhile.
    The knee wall shown in the pic is bulged out about 1 1/2 in the middle. The other walls are fine.
     

Share This Page