I looked at a duplex yesterday that I'm scheduled to buy next week. I mentioned this in another post. I did an inspection of the property on Friday.
There is a section of roof where the rafters appear to be sagging. Its not just sagging between rafters. I took a pic but the sagging it not as noticeable in the pic as it is in person.
The overhang portion of the roof on the gable end(right side of pic) is not sagging at all. I'm assuming that exterior wall on the right side is keeping the roof from sagging. But, just inside gable overhang is where the rafters are sagging. Sepecifically its sagging towards the lower 1/3 of the roof.
The ceiling below the sagging portion is a vaulted ceiling. There are no cracks or anything in the ceiling or the wall that the rafters rest on. The exterior wall(brick portion in pic) does not seem like there has be any movement.
How common is a section of sagging rafters and is it something I should be conerned about? The property is about 15 years old. I believe the rafters are 2x6 and 24 inches on center. Not sure of the thickness of the roof sheathing
From the explanation, I couldn't load that site, it sounds like the sagging is at the eves? I'm not a roofing guy or framer, but false rafters are common where the rafter extends beyound the load bearing wall. These can get weaker and exposed to more weather conditions than interior members. Fairly easy to cure by taking the soffit down, remove, jack decking into palce as needed and replace them and replace the soffit. You may need to replace the flying or outer rafter and trim, as it may be sagging and drawing the roof down.
If I followed that right....
If the roof is sagging over a cathedral ceiling, it might be easier to inspect the underside of the roof from the outside opening the soffit. If you have weak rafters, you might be able to scab on along side an existing rafter from the soffit and above the top plate. You can use 2bys to pry the roof up if it's not bad. I have had to do this before and it's a job. Depends on many factors of access how easy it might be. You may need to cut holes in the roof (a section) and repair it, and build your roof decking and roofing back from the top side. Romiving a section of roof needs to be done along the centers of adjacent rafters so you have a nailer....better yet, get some bids, while it is not rocket science, it's not for the average DIYer, you'll need some construction experience....and be careful.
PS. A sagging roof rafter can also be braced up from ceiling joists if a wall plate is not near by. You'll need to lay your base of the "A" frame over several ceiling joists to disipate the laod, one will not brace a rafter and you can damage your ceiling. Place the base on edge and scab on the side to the rafter, at a 45 degree slope and nail to the rafter, the base is running perpendicular to the rafter and ceiling joists. I have notched the base so that it sits at an angle over the joists, like a bids mouth type notch and nail to the joists.
Man that's hard to explain! Hope you got the idea.
In fact, if you don't have experience, get some help. Just thinking, you need to look at anything you tie in to and make sure it will carry the expected load, Following my suggestion above of bracing a rafter and tieing into joists that are floating and not laid above the top plate, will cause problems...you need to realize how weight is distributed and carried, all the way down to the foundation. Good luck
Thanks for the detailed answer Bill.
You may try to the pic. link again. It seemed to work for me.
Its not sagging at the eaves.
There is no attich space below the sagging portion either.
Your second paragraph describes it best as it is a cathedral ceiling. I'm going to have someone take a look at it and see if its bad enought to need repairing. Removing shingles, roof decking and then sister another rafter does sound like a pain.
It looks to me like most of the issue is in the fly rafter (barge rafter or sub-fascia) from your picture it looks like is has a bad upward bow. Since this is your reference point it makes any sag look that much worse.
If it is framed like they frame things around here a slight sag in the second truss will translate to a rise in the fascia if the framer doesn't care about straight lines.
It is very hard to tell from just one picture :)
I just checked and it looks as though you are in Missouri. Likely it is just rafters and not trusses. This is likely just a rafter or 2 that bowed after install or were put in with a downward bow when the rest of them were either straight or with an upward bow. Shouldn't be a big deal structurally. It just looks bad.