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  1. #1
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    Default Weird, Moving Creaks In The Roof System

    This is kind of a weird one. It's long too (no surprise there).


    I was called out to take a look at a coastal home that was having weird running creaks across the interior of the home.


    I don't have pics, but they really would not be of much help.


    The original part of the home was built in the mid 1950s and is in the Eichlers style, but on a perimeter foundation rather than slab-on-grade.

    The owner hired a contractor to add-on a master bedroom suite at the right side of the home where the attached single-car garage was. The plans have an engineers stamp and was inspected by the county building department. I could find no obvious problems with the build. Overall, it looks good.


    The original/attached garage was pulled-down (except for the common wall between the original house and the old garage) and new walls and roof framing constructed for the master suite. A new garage was built farther to the right.


    The roof membrane is a low-sloped, built-up (hot-mopped) with a granulated cap sheet. The roof framing is "open-beam" at the interior.


    The basic construction of the original roof, from the top-down is:
    3-ply hot-mopped membrane with a granulated cap sheet.
    1/2" plywood
    1" of rigid polystyrene insulation
    2x6 tongue & groove solid-wood sheathing
    4x8 wood beams on 48" centers


    The construction of the new roof, from the top-down is:
    3-ply hot-mopped membrane with a granulated cap sheet.
    1/2" board between the membrane and the insulation (I forget the brand)
    5-1/2" rigid polystyrene secured as per the manufacturer's installation instructions.
    1/2" struct-one plywood
    2x6 tongue & groove solid-wood sheathing, gapped 1/8" at the perimeter of each panel
    4x8 wood beams on 48" centers


    The plywood is nailed to the solid decking over the girders only.


    Several times each day, the roof above the new section creaks in a cascade from one end to the other. Most noticeable in the middle of the night (we're guessing because there are no other sounds) and mid-morning, but it also happens at other times of the day. This does not appear to be related to exterior temperature as it will happen on warm, sunny days or cool, cloudy days. The sound is a bit louder than wood floor squeaks, but sharp. A fairly rapid "popping" sound that moves from one end of the room to the other. Nothing from the older/original section, only the new.


    The new section is a bit less than 2 years old, so I expect any major wood shrinkage should have happened by now.


    A few months ago, the contractor pulled-up a section of the roof membrane above the master and added additional fasteners through the insulation, plywood, decking, and into the 4x8s, thinking that maybe the sound was insulation movement. No noticeable change in the creaking.


    My guess is that the solid wood and the plywood do not expand/contract the same amount/rate and we are hearing the two sliding across each other, but that is only a guess.


    Has anyone here hear of anything like this before? Does anyone have any suggestions? Both the owner and contractor are losing sleep over this.

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  2. #2
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    Default Re: Weird, Moving Creaks In The Roof System

    I'm thinking thermal expansion above the 2x6 T&G.

    Jerry Peck
    Construction Litigation Consultant ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  3. #3
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    Default Re: Weird, Moving Creaks In The Roof System

    We moved into a house that I built in September. We have a 1x6 T&G ceiling, and it pops pretty loud at various times. It will definitely wake me up in the middle of the night. It is apparently pretty common, regardless of age, wood dryness, etc. I have not found any way to correct it.




    Jim Robinson
    New Mexico, USA

  4. #4
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    Default Re: Weird, Moving Creaks In The Roof System

    I call it "thermal cycling", and have an issue in my home similar to that. Definitely ceiling/structure related (in my case at least).

    Temperature swings seem to bring it out, whether its hot or cold out, sooner or later, the temperature changes and the noise appears. It's very annoying.


  5. #5
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    Default Re: Weird, Moving Creaks In The Roof System

    Think in terms of what is provided around a 1x T&G wood floor - expansion space around the perimeter, which is mostly for expansion and contraction due to humidity as, thermally, the temperature doesn't change a lot.

    With a 1x T&G ceiling/roof decking/insulation/roof covering system, the 1x T&G is exposed to much greater temperature swings (that 1" rigid insulation is what, maybe R-5 at the most?).

    If that insulation is only R-5 ... how does it meet the energy code?

    Jerry Peck
    Construction Litigation Consultant ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  6. #6
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    Default Re: Weird, Moving Creaks In The Roof System

    Quote Originally Posted by Jim Robinson View Post
    We moved into a house that I built in September. We have a 1x6 T&G ceiling, and it pops pretty loud at various times. It will definitely wake me up in the middle of the night. It is apparently pretty common, regardless of age, wood dryness, etc. I have not found any way to correct it.
    Jim,

    What is the roof construction in your home? Is this open-beam with rigid insulation or standard ceiling joists?

    The odd thing (to me) is that this is only happening in the newer portion of the house. Both have similar roof construction, the primary difference being the age, plywood, and thickness of rigid insulation. Presumably, there is an occasional creak from the original, but the new portion is doing it multiple times each day.

    Quote Originally Posted by Dom D'Agostino View Post
    I call it "thermal cycling", and have an issue in my home similar to that. Definitely ceiling/structure related (in my case at least). Temperature swings seem to bring it out, whether its hot or cold out, sooner or later, the temperature changes and the noise appears. It's very annoying.
    Dom,

    Same question. Is yours open-beam or rafters & joists?

    Quote Originally Posted by Jerry Peck View Post
    Think in terms of what is provided around a 1x T&G wood floor - expansion space around the perimeter, which is mostly for expansion and contraction due to humidity as, thermally, the temperature doesn't change a lot.
    With a 1x T&G ceiling/roof decking/insulation/roof covering system, the 1x T&G is exposed to much greater temperature swings (that 1" rigid insulation is what, maybe R-5 at the most?).
    If that insulation is only R-5 ... how does it meet the energy code?
    Jerry,

    Not sure if your questions were directed at me. A couple of clarifications and one correction.

    1. The T&G in both portions is 2x6. Exposed in the interior.
    2. The rigid polystyrene on the new portion is 5-1/2". The old portion is 1". To the best of my knowledge, no requirement here in CA to upgrade insulation on existing. Certainly would have been a good idea and is encouraged, but the exterior walls of the original portion probably have no insulation as well. The belief in the '50s was "Insulation? We don' need no stinkin' insulation!"
    3. The 1/8" spacing is for the plywood, not the T&G like I originally stated.


    I am unclear how the humidity could change that rapidly. Heat, I understand, but I wouldn't have thought that RH would change repeatedly throughout the day.

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    http://www.FullCircleInspect.com/

  7. #7
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    Default Re: Weird, Moving Creaks In The Roof System

    [QUOTE=Gunnar Alquist;287730]Jim,

    What is the roof construction in your home? Is this open-beam with rigid insulation or standard ceiling joists?

    I tried to post a picture, but the dumb resizing thing frustrates me too much.

    It is a parallel scissor truss framing. 24" OC, with about R 60 blown in fiberglass. We used the Intello membrane in between the T&G and the framing. The roof is pretty conventional 5/8" OSB with metal panel roofing. It's newish, but all of the roof framing was in place for over a year before we put up the T&G, and the T&G was on site for several weeks to acclimate. It was probably six months from when we put the ceiling up until we moved in. I was pretty surprised at how loud it was the first night we slept here. Definitely didn't see that coming. I think it's just one of those things you get used to after moving to a new house. Sort of like my neighbor's dogs outside the bedroom window.

    Jim Robinson
    New Mexico, USA

  8. #8
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    Default Re: Weird, Moving Creaks In The Roof System

    While most of my home is trussed, the majority of the noise is at the stick-framed portion.
    The noise can sound like fireworks at times. Very prominent when a cold front suddenly moves in.


  9. #9
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    Default Re: Weird, Moving Creaks In The Roof System

    Gunnar,

    My humidity reference was to wood floors and the gap around them to allow for expansion (albeit slow expansion, and due to humidity changes over the months).

    Whereas 2x T&G (or 1x T&G) ceilings with the roof directly on it (no ventilation between ceiling and roof) can cause more rapid expansion and contraction.

    More rapid expansion and contraction leaves less time for the wood to more gently slip around, resulting in incremental 'pops' (end to end parallel with the grain expansion is less per inch, it also is accompanied with greater lengths, where expansion perpendicular to the grain is greater per inch, it is also accompanied by lesser widths).

    Sure it is all "nailed in place and shouldn't move", put the nails do allow movement, but each nail just adds to the 'squeak' noises when the wood moves.

    With a difference in installation thickness, are we to presume that the roof level (plane) is not continuous from older construction to new addition?

    Where is the noise greatest, old or new?

    Jerry Peck
    Construction Litigation Consultant ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

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