Sagging roof over cathedral ceiling

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Old 07-25-18, 05:22 PM
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Sagging roof over cathedral ceiling

Hi! My name is Ben and I'm new here.

I'm getting ready to replace the shingles on my roof but noticed that my roof is sagging quite a bit. I put a string from one end to the other (near the ridge line) and found that half the house has sunk by about 2".

The house is framed in an unusual way, with half of the house having a gable roof and the other half with a combination of cathedral/knee wall(?) and flat roof. The part of the house with the gable framing looks great, it's the section with the cathedral ceiling that has problems.

I don't really want to slap some new shingles on it and walk away, but jacking up the roof on half of my house seems like a HUGE project. Any suggestions or experience with this sort of situation? Thank you!
 
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Old 07-25-18, 05:39 PM
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I would check on the inside of the house as well. Is the floor in the same area sagged? Check the bottom of the beam (window) wall right below the roof where you measured. Is it sagging like the roof?

I don't see any cracks in your wall. If the floor is straight and level and the bottom of the beam window wall is also straight then it's possible the roof was framed that way. I would check for rot and broken beams and joists but maybe that's just the way it's made.
 
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Old 07-25-18, 07:17 PM
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In addition...

You should also check the wall in front of the house (the wall opposite the windows) to see if it's leaning away from the windows at the top. Put a string line on the interior surface of the wall near the top and check it from end to end.

You can do the same thing to the wall above the windows (picture 2) by dropping the string line over peak of the roof and see if the wall is straight or is leaning in or out. If it's leaning out, you may have to shim the ends of the string line out (evenly) on the ends until the string clears the bow.

And then check the roof at the middle and bottom... not just the top. Report what you find.

You also didn't tell us anything about what is below this area. Is this a cement pad? Is there a basement?
 
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Old 07-26-18, 09:05 AM
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Thank you for the replies!

As far as inside the house goes, we had some remodeling done a few years ago that has masked some of the signs. I do recall the floor having a pretty good low spot under the (4x4) beam supporting the knee wall (shown in the first pic). At the time, the floor guys just throught it was normal settling and so they filled in the low spot with filler.

Around the same time (shortly after buying the home, which was built in 1978), I was hearing pops and cracks coming from the knee wall. I had a structural engineer come over to check it out and was told that a full structural report would run well into the thousands and would be overkill because he didn't think it was a big deal. He suggested that if i was concerned, I could reinforce the knee wall to the beam using plywood to stop the wall from acting like a hinge. So that's what I did in 2010 and the sounds have been reduced but not eliminated.

The beam supporting the wall is in good shape, although it's supported by what seams like an undersized 4x4. The house is built mostly over a crawl space with a small portion having a slab. The perimeter of the house has a foundation with piers/footings in the middle. I put a level on the wall opposite the knee wall with the windows and it looks like its leaning in towards the house slightly. The knee wall is leaning out for sure, like an inch or more.

I can't get up on the roof until later tonight, but I'll be sure to string a line on the other parts of the roof.

Thank you!
 
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Old 07-26-18, 09:19 AM
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It sounds like your problem could be down at the foundation. I suspect there is a lack of support underneath the floor where your 4x4 is located. If you're main floor hadn't been filled I would suggest fixing the underlying foundation support issue in the middle of the room. It could have been jacked bringing everything above back into line. If you do it now it could straighten the roof but because of the filler the main floor would probably have a hump.
 
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Old 07-27-18, 02:33 PM
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I was able to get up on the roof and found that the sinking has mostly occurred near the peak of the roof. The lowest part of the roof isn't perfectly flat but it's good enough. The middle of the roof is somewhere in between.

Is there a rule of thumb for how to handle a situation like this? If it were 1/2" I wouldn't think too much about it, but 2" seems like a lot to me.
 
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Old 07-27-18, 03:38 PM
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If you don't want to get into the drywall ceiling or wall, the simple thing to do would be to open up the ridge and back side of the wall (above the windows.) Mount a ledger onto the wall that will run straight. Could be anything... a 2x8, for instance. ( you could trim it later with an LP Smart trim 5/4 x 8) Shim the 2x8 out, if needed so it runs as straight as a string line is... screw to each stud with ledger loks. The top of the ledger on each end should plane with the tops of the rafters on each end.

When you are ready to tear off the roof, you can remove the sheathing, sister long 2x6's onto the rafters that will plane right into the top of the new ledger, then resheet the roof. A more complicated way would be to actually shim each individual rafter with a sleeper on top. That would be pretty time consuming but you could get the roof perfect that way if you really wanted to.... with a string line across the bottom, then a string line down each rafter.
 
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