Roof Ridge Beam Sag

Originally Posted By: Stan Sacha
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[ Image: beam sag.JPG ]

I was recently on my roof and noticed the ridge beam sags toward the fireplace. The fireplace divides a great room, both having cathedral ceilings. Dimensions of the living room (to the right of the fireplace) is 15X21, and the dining room (to the left of the fireplace) is 15X12. The sag appears to total about 4-5 inches. I just had the flashing and plywood around the fireplace replaced due to leakage around the fireplace. The person who replaced the flashing stated the original flashing had been installed incorrectly, hence the leak. The house is about 25 years old and currently has 2 layers of roofing. Is the ridge beam sag something to be concrned about and is major repairs inevidable, or is this normal for such a span and age of house? Is there anthing else I should check to see if this is a significant problem?

Thanks much.

Originally Posted By: ckratzer
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First and foremost I am a builder so you know my questions or ideas are going to evolve from my 25yrs. of experiance in new and old homes.

  1. 4-5" in 25yrs. is not normal.

    Lets start your fact finding in the basement.

    If the floor is concrete and has significant cracks around the fire place area this could be a significant clue that the whole fire place has settled.Are cracks present on the fire place?There could possibly be improper footing under the fire place or the footing has simply failed.

    If the floor is a crawl space can you get to and inspect the base of the fire place for evidence of sinking or cracks on the fireplace?

    Are the living area floors around the fireplace sagging into the fireplace as well?

    Do your cathedral ceilings end in a point or is there a small amount of flat ceiling at its apex?

    If it ends in a point and there are no other forms of collar ties are the adjacent walls pushing out at the top? (check for plumb with a level).If the walls are spreading this could be the problem.

    A small amount of flat ceiling is usually an indicator of collar ties being present and ,in my opinion, a stronger design.

    As far as failed flashing goes it will fail if it shifts dramatically and 4-5" is pretty dramatic.Plus your roof sloping into your chimney is an open invitation to water when the flashing does fail.

    There’s a good chance you could use a structural engineer on this one to tell you how to fix it and then find a good contractor who understands the engineers instructions.


Originally Posted By: Stan Sacha
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Thanks much for the reply. I didn’t think that kind of sag is normal. I’m going to verify the specific measurement with a laser level. I did check the base of the fireplace, which is in the basement, as well as the first floor where the fireplace runs through. Both are level and have no indications of settling.

Unfortunately, there is no small amount of flat ceiling. I agree collar ties are a stronger design. I will check the walls to see if they are pushing out.

Thanks again for the input. Stan

Originally Posted By: twheeler
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A common area for sagging in a roof indeed.

When a chimney has to pass through a roofline, the ridge beam stops at that point, and if it is not supported properly in the attic, and given the fact that the roof has two layer of shingles, it can, and in most cases, cause sagging in the roof.