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  1. #1
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    Default Worn ridge shingles,wavy sheathing

    Just finished a manufactured home, hatched in 1994. I have never seen the ridge shingles in such bad shape compared to the rest of the shingles. Any ideas. Also what would be the best way to word the "wavyness" of the sheathing. I walked it, it wasnt spongy, and no attic so cant see from the bottom of sheathing. That small hill in the background is Pikes Peak.

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  2. #2
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    Default Re: Worn ridge shingles,wavy sheathing

    No idea on the ridge shingles other than they look like they are folded over and interlocked...not something I've ever seen. But they also look like they are 40-50 years old! Damn odd, but an easy call for replacement.

    "Also what would be the best way to word the "wavyness" of the sheathing."

    Excessive? I would imagine that that much sag between rafters was due to moisture entry problems from the home in that area, or bad ventilation, or a combination of the two. What was directly underneath? Maybe they have since fixed that problem, and maybe the sheathing has dryed hard in that shape, which may be why it doesn't feel spongy now. BUT...I'll bet it was very spongy at some point and, IMO, you need to recommend that area gets torn up, investigated for underlying damage (and the root cause), and then, of course, repaired.


  3. #3
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    Default Re: Worn ridge shingles,wavy sheathing

    Thanks Richard, I thought about the ventilation issue. I have yet to see a manufactured home (with cathederal ceilings) with any ventilation whatsoever. I guess I will just recommend a roofer to look at it. The buyer is basically buying it for the 35 acres its sitting on...

    Paul Kondzich
    Ft. Myers, FL.

  4. #4
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    Default Re: Worn ridge shingles,wavy sheathing

    After one POS early in my career I made the decision not to do manufactured homes, so I don't know what ventilation is typical for these things. Are they relying on cross ventilation from the soffits?

    If this was a "normal" home I'd be very concerned about the lack of high roof vents. There doesn't appear to be enough space under the ridge shingles for a continuous ridge vent.


  5. #5
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    Default Re: Worn ridge shingles,wavy sheathing

    I would imagine the ridge shingles are a totally different kind of shingle that was site applied after the unit was placed if it was a "double wide" type.
    Even on site built homes, the ridge shingles are sometimes different than the field shingles since the architectural style don't work for the ridge. Could be just a bad batch of shingles. Anyway, replacement is the answer.
    Can't tell much about the sag from the picture, but I would be looking inside to see the support for the ridge. Some of the double wide type construction will rely on the opposite structure to support the ridge. A structural "Trim" bolted to the supporting wall that the other half rests on.

    A 1994 model is about at the end of its useful life anyway. The last time someone told me they were "really" just buying it for the land, came back and wanted me to be on the hook for termite damage a few years later. Document everything, just in case.

    Jim Luttrall
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    Default Re: Worn ridge shingles,wavy sheathing

    Did you walk on those areas of the roof sheathing? (I would not have, you probably did not either.)

    Roof sheathing "particle board"? A little moisture and that particle board could sag like that between the rafters.

    OSB or plywood would tend to hold itself up better than than, even if the plywood was installed with the face grain parallel with the supports instead of perpendicular to the supports.

    My first thought was plywood parallel with the supports, then I thought ... oh-oh ... I betcha 'manufactured home' = 'particle board' back then.

    Jerry Peck
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  7. #7
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    Default Re: Worn ridge shingles,wavy sheathing

    Jerry, not sure if plywood or particle board. I suppose I could have checked at the edges (note to self.) I wanted off of there asap, didnt want to make a surprise entrance...

    Paul Kondzich
    Ft. Myers, FL.

  8. #8
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    Default Re: Worn ridge shingles,wavy sheathing

    The ridge cap is a particularly poor material that I run into fairly frequently around here. It is essentially felt paper with granules stuck to it. These were sold to roofers to give the ridgeline some "dimension". It typically lasts about 10 years. Essentially a bad product.

    Roof sheathing on mobiles is often wavy. The often use 1/2" 3-ply on 24" centers instead of 5 ply. As a result, the sheathing sags and will deflect noticeably when walked on.

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    Default Re: Worn ridge shingles,wavy sheathing

    Quote Originally Posted by Gunnar Alquist View Post
    The often use 1/2" 3-ply on 24" centers instead of 5 ply. As a result, the sheathing sags and will deflect noticeably when walked on.
    Gunnar,

    That roof is more than just 'deflection', that is 'sagging' as in 'draping cloth across trusses'.

    As soon as that sagging starts, you will get lateral movement of water across the shingles, which are not made for resisting the flow of water laterally across them, which can (typically does) lead to leaks.

    Those leaks will weaken the sheathing, causing greater sagging, causing even more water to run laterally across those shingles, leading to more leaks, and-on-and-on-it-gets-worse-every-year.

    The problem I am having is that, with plywood, you have some sense a rigidity across the tops of the trusses, leading to a more subdued bowing effect, that photo shows it like the material is just draped across the trusses. If you've ever seen particle board after it has gotten wet, especially repeatedly, not only does it swell and fall apart, it sags like that shown in the photo.

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    Default Re: Worn ridge shingles,wavy sheathing

    i tend to agree with jp about roof ply being parallel to supports. what is the snow load of the mh and the snow load of the area? heavy snow possibly cause sagging between supports?


  11. #11
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    Default Re: Worn ridge shingles,wavy sheathing

    Jerry,

    You could be right. The subfloor in mobile homes is always (as far as I have seen) particleboard. I had thought that they generally used plywood for roof sheathing though. It could be that some manufacturers use particleboard. I would have thought that Paul would have felt deflection or "spongyness" when he walked across the roof.

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    Default Re: Worn ridge shingles,wavy sheathing

    Thats what had me baffled the roof did not seem spongy. As far as the snow load last year we had 3 3ft. snows. Havent seen this on other MH though. The buyer is calling a roofer, and I am supposed to hear from him as what his diagnosis is.

    Paul Kondzich
    Ft. Myers, FL.

  13. #13
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    Default Re: Worn ridge shingles,wavy sheathing

    Jerry, you are pretty good at estimating distances from a photo. Can you tell what the rafter spacing is between sags? That looked more than 2' on first glance like maybe missing supports, but the more I look the more it looks like snow load an damaged sheathing.

    Jim Luttrall
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    Default Re: Worn ridge shingles,wavy sheathing

    Quote Originally Posted by Jim Luttrall View Post
    Jerry, you are pretty good at estimating distances from a photo. Can you tell what the rafter spacing is between sags?
    Well, eyeballing my thumb to the ridges between the dips, its about one thumb width, being as my thumb is about 1 inch wide (give or take), those supports are ....

    That looked more than 2' on first glance like maybe missing supports,
    ... 3-1/2 to 4 feet apart (give or take).

    (Ask me how I got that. )

    Jerry Peck
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  15. #15
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    Default Re: Worn ridge shingles,wavy sheathing

    Quote Originally Posted by Jerry Peck View Post

    ... 3-1/2 to 4 feet apart (give or take).

    (Ask me how I got that. )
    i
    Number of shingles between x length of shingle.

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    Default Re: Worn ridge shingles,wavy sheathing

    Quote Originally Posted by Billy Stephens View Post
    i
    Number of shingles between x length of shingle.
    And what did you get?

    (You spoiled all the fun, I was going to go into detail about an algorithm, triangulation and the trapezoidal effects and blah-blah-blah, and end it with ... 'and then finally counted the number of 1 foot long shingle tabs between ridges'. )

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  17. #17
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    Default Re: Worn ridge shingles,wavy sheathing

    Mr. Peck,

    Without the benefit of a command center with mulit -synchronized monitors and Hubble assist. I would put the distance at 42 in.


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  18. #18
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    Default Re: Worn ridge shingles,wavy sheathing

    Of course I could have just asked Paul (who was there)... Duh!
    Anyway, that distance estimate kind of supports my initial theory of lack of support, assuming that the maximum spacing would typically be 2' on center.
    Looks like the ridge side truss support has failed in several places, trailing off to the outside wall where the sag in the decking is less pronounced since the truss or rafter would have continuous support there.
    What do you guys think?

    Jim Luttrall
    www.MrInspector.net
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  19. #19
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    Default Re: Worn ridge shingles,wavy sheathing

    Quote Originally Posted by Billy Stephens View Post
    Without the benefit of a command center with mulit -synchronized monitors and Hubble assist.
    The Hubble has a finger print on it whichis blurring it a bit.

    I would put the distance at 42 in.
    So we are either 'right on' or 6" difference, not too bad considering the thumb width varies using the thumb-width-to-target-vector method.

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  20. #20
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    Default Re: Worn ridge shingles,wavy sheathing

    Quote Originally Posted by Jim Luttrall View Post
    What do you guys think?
    Mc Manson's are a different breed regulated under HUD. Max. distance could be 48".

    Picture# 3 still has moisture showing in sagged area of roof.

    With a 3 foot season of snow fall and this area being the last to melt. I could see a snow
    load build up to snap the sheathing as shown.

    Last edited by Billy Stephens; 10-26-2007 at 08:44 PM. Reason: pic# 2 to 3
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  21. #21
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    Default Re: Worn ridge shingles,wavy sheathing

    With a 3 foot snow load, when it starts to melt underneath, it's going to become one big pond at each sagging area, and shingles are made to shed water, not hold water. That water is going to run out laterally for sure.

    I think Billy is right in saying "I could see a snow load build up to snap the sheathing as shown." - that is what it looks like - a snap line down the center of the dip.

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