Sagging garage roof concern


I had a general inspector come out and do an inspection on my home and later discovered a sagging garage roof. The sag was not mentioned in the report. After I alerted the company, the owner of the company came out to do follow up inspection after I told them about the sag in the middle of the roof and he told me that it’s fine and just cosmetic. He walked on the roof and said it’s secure and the sag is based on how the builders built it. He assured me that the roof is not coming down and the sag won’t shorten the roof’s life expectancy. Note: the roof is 2 years old and was done by the former owners of the home we just bought. I’m a little unsettled because I’ve read elsewhere that roofs should not sag. Would you kindly be able to look at the pics in the PDF and let me know if the sag seems like it should be fixed? Here is a dropbox link to a PDF I made with pictures. Dropbox - Garage Roof.pdf - Simplify your life

How is the roof framed? Rafters or trusses?
Pictures of the underside of the roof?

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This often happens when the exterior walls spread apart because of improper or lack of rafter ties. You should check the exterior walls for bowing. You can do this with a string and few blocks. If the walls are bowed in the center then most likely that’s the reason for the sagging ridge. Does the garage have a ceiling? do you have pictures of the framing of the roof from the inside?


Thank you so much for your help and replies!

@David (good name!) it’s built on rafters and I enclosed pictures here. Dropbox - Roof inside.pdf - Simplify your life The ceiling of the garage that the roof supports is made of foam boards.

@Simon, thank you for this tip. I’m going to head out and grab string today to do the test. In the meantime, I took this pic of the side of the garage wall from the outside. The green line is a straight line and the pink line is where I can see the end of the wall poke out from around the corner of the front wall. Dropbox - garage side.jpg - Simplify your life

David I’m not seeing anything in those pictures that would make me think that garage was in any kind of jeopardy…

There appears to be missing rafter tie(s). The center where you took the pics inside, there is a large gap without a tie. The wooden 2x that are right above the suspended ceiling are the rafter ties, they tie the left and the right wall that are parallel to the ridge. They are supposed to be spaced every 48 inches or less. How big is the gap between the rafter ties in the center where there appears to be a missing rafter tie? Using a string, run it from one end of the wall to the other (not from top to bottom). Do this at the top of the wall. Off set each end with a block, or similar, by exactly 2 inches. Tie the string tight. Then measure from the wall to the string in the center. The closer it is to the string the more bowed the wall is. From the pictures alone, the framing does not look too bad. In reality, it is not going anywhere anytime soon.

What is your concern? before you purchased, you knew at least cosmetically, the ridge was uneven.

In the first set of pictures you posted, there is a hump at the drip edge over the man door in line with the dip in the ridge. It almost looks like the rafter tails in that area moved upward when the ridge beam sagged. The lack of rafter ties would also cause this. After you check the walls for bowing as Simon suggested, run the string along the bottom of the roof line as well. Be sure the string is VERY tight when you check both items.

That low pitch roof puts a lot of outward thrust on the walls, which can create a sag in the ridgeline. In addition, those 2x6 rafters are spaced farther apart than normal which can cause the rafters to bow downward in the middle. Any bow in the rafters will also cause the ridgeline to sag.