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  1. #16
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    Default Re: How Long the Story Pole

    Quote Originally Posted by m beezo View Post
    I know very little about the hold downs that you talk about. I am not sure they are anything that are required here, certainly not on anything that I have built so far. When you talk about taking up the slack, these things are accessible so you can do that?
    No, they automatically take up the slack- there are spring-loaded ones and ratcheting ones. Scroll down and there's an image of the spring-type in that link. You put them on the threaded rod and they allow you to push ahead and close up the wall before shrinkage sets in.

    kevin
    “It is difficult to get a man to understand something, when his salary depends on his not understanding it.” - Upton Sinclair

  2. #17
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    Default Re: How Long the Story Pole

    Incidentally, the 2:1 difference between tangential shrinkage and radial shrinkage is the reason boards cup. Unless the board is v.g., one face will be more or less tangential to the growth rings, while the opposite will be more or less radial.

    When the face that is tangential shrinks twice as much as the opposite face, the board has to change shape or tear apart. Often it will do a bit of both.

    You'll hear/read a lot of <...edit...> theories about why/where/how boards cup, but the <edit: most intrinsic> is the .01%/4%/8% breakdown I gave above.
    Attached Images Attached Images
    Last edited by kfc510; 01-07-2014 at 12:36 PM. Reason: removed kinda douchey language
    “It is difficult to get a man to understand something, when his salary depends on his not understanding it.” - Upton Sinclair

  3. #18
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    Default Re: How Long the Story Pole

    Quote Originally Posted by m beezo View Post
    if you guys are really serious about a house shrinking up to 3/4 an inch for a 2 story I cannot understand why we don't have more call backs about house cracks, doors not working, windows not working. The frame is attached to everything so why is the drywall not buckling, siding getting all wonky looking, doors not dragging or not shutting. That seems like a huge amount even to the math seems to say so.
    In most cases, the siding, doors and windows will be attached to only one component of the frame. So, if a stud does shrink, it really wouldn't affect a door or window. If all the joists shrink, all components resting on it will settle at the same rate.

    Also, we now typically install OSB sheathing. It doesn't shrink. That would indicate to me that the exterior of the frame retains it's shape while the framing members shrink leaving cracks.

    Here in MI, we don't typically sheath over the rim joist. So, it's theoretically possible that the second floor joist system could lose a 1/4" in height, in the floor elevation area only, and thus affect the siding exposures. That in itself wouldn't matter...unless the siding is also nailed to a tall ballooned wall adjacent to the two floor area. Also, the corner boards would also be affected if they fit tight to a perimeter water table (or frieze board), which is also typical of how we build.

    Houses do get wonky from the shrinkage on the interior. It happens over an extended period of time and the inhabitants don't really notice, until a door starts sticking. We've all encountered doors that stick. They didn't stick when the trimmers set them, did they?

  4. #19
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    Default Re: How Long the Story Pole

    Thanks KFC for those sketches and shrinkage rates. That's good stuff.

    Your cupping explanation makes perfect sense if all sides are wet or dry equally. Quite often, out in the jobsites, a board will cup severely when one side is exposed to the hot sun while absorbing moisture from underneath. I typically flip the wide boards over to re-flatten them, so they will be easier to nail up when I get around to using them. They usually flatten out within 24 hrs around these parts.
    Last edited by jimAKAblue; 01-07-2014 at 02:06 PM.

  5. #20
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    St Louis, Mo for the past 25 years
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    Default Re: How Long the Story Pole

    Quote Originally Posted by jimAKAblue View Post
    .

    Also, we now typically install OSB sheathing. It doesn't shrink. That would indicate to me that the exterior of the frame retains it's shape while the framing members shrink leaving cracks.

    Here in MI, we don't typically sheath over the rim joist.
    NOt sure how the exterior frame retains it's shape yet you say the framing shrinks. So the OSB stays the same and the nails just bend as the boards shrink? Of course the OSB would be nailed to the studs mostly so shrinkage would be very little.

    Around here I know that we attach the sheathing to the rim joists. This is partly to help tie the house to the floor framing which is tied to the foundation. If you do not cover it with sheathing what are you doing to cover it? Or are you just building them out to the same plane as the sheathing will be installed.

  6. #21
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    Default Re: How Long the Story Pole

    Yes, the rim is in the same plane as the sheathing on the upper and lower floors.

  7. #22
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    Jul 2006
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    Portland, OR
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    Default Re: How Long the Story Pole

    Drywall on ceilings is unaffected by shrinkage in the bearing systems. Drywall on walls, if done correctly, is installed with a 1/4" gap at the bottom. As bottom plate shrinks, gap gets smaller, but stresses are not put into the drywall.

    Shrinkage of the floor framing, as well explained above, is where the difficulties come in. Flat straps across the floor lines can bow out, pushing out the siding.

    Then there are brick veneer issues. Brick can be up to 22' tall, self supporting. (Your code may vary). Tall enough to get to a window sill on the third floor. So there you have a vinyl window attached to framing and projecting into a masonry opening. Framing shrinks, brick doesn't (may even expand). How wide a sealant joint should there be below the sill of that third floor window?

  8. #23
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    Nov 2006
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    Calyfornia
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    726

    Default Re: How Long the Story Pole

    Interesting Jim, seems like an effective solution although we would never get away with it here. Usually the SE wants ply spanning the rim with nailing patterns anywhere from 6" to 2" oc depending on the shear wall design.
    As for the shrinkage factor I wouldn't know where most of it happens although KFCs numbers make total sense, but it does happen. It's pretty hilly here and lots of houses sitting on them end up looking like high heeled shoes. Three stories on the down hill side and one on the up isn't uncommon. Every single one i've been in has been significantly sloped to the downhill, and it's not foundation movement.

  9. #24
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    Default Re: How Long the Story Pole

    Quote Originally Posted by jimAKAblue View Post
    Thanks KFC for those sketches and shrinkage rates. That's good stuff.

    Your cupping explanation makes perfect sense if all sides are wet or dry equally. Quite often, out in the jobsites, a board will cup severely when one side is exposed to the hot sun while absorbing moisture from underneath.
    You're welcome, Jim.

    Yeah, part of the reason I edited my post about cupping was that I originally kind of pooh-poohed the "wet underneath" explanation that a lot of guys give, and I wanted to take the know-it-all attitude out of my post.

    I can see how differential swelling would have the same effect as differential shrinkage. I always (and I mean ALWAYS) see boards cup the same way with respect to the growth rings, so I tend to dismiss that theory, but it's entirely possible I just haven't been in the right conditions. Around here, when it's wet it's wet for a while, when it's dry it's dry for a while, and the boards mostly reach equal moisture on all sides. I could see other climates causing other conditions.

    I've posted this link before, but it goes over a lot of the basics of wood movement:
    http://workshopcompanion.com/KnowHow...d_Movement.htm

    kevin
    “It is difficult to get a man to understand something, when his salary depends on his not understanding it.” - Upton Sinclair

  10. #25
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    Default Re: How Long the Story Pole

    For those who may be interested there's...

    http://owic.oregonstate.edu/wood-shrinkswell-estimator

    ...of course more at FPL
    “I find the curiosity of our men with respect to this animal is pretty much satisfied.”
    ~ Meriwether Lewis

  11. #26
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    Default Re: How Long the Story Pole

    Quote Originally Posted by MarkMc View Post
    For those who may be interested there's...

    http://owic.oregonstate.edu/wood-shrinkswell-estimator

    ...of course more at FPL
    Simpson has a shrinkage calculator as well- I ran a two story solid framed DF (2x8 joists) structure and it gave me about 1/2" of total shrinkage: http://www.strongtie.com/webapps/woodshrinkage/

    kevin
    “It is difficult to get a man to understand something, when his salary depends on his not understanding it.” - Upton Sinclair

  12. #27
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    Default Re: How Long the Story Pole

    Quote Originally Posted by m beezo View Post
    NOt sure how the exterior frame retains it's shape yet you say the framing shrinks. So the OSB stays the same and the nails just bend as the boards shrink? Of course the OSB would be nailed to the studs mostly so shrinkage would be very little.

    Around here I know that we attach the sheathing to the rim joists. This is partly to help tie the house to the floor framing which is tied to the foundation.
    The sheathing will act as a vertical load carrying element to some extent, depending on its thickness, and the gap it has to span, etc. If a plate shrinks 1/16" it might pull up 1/32nd from the studs it's on and pull down 1/32nd from the joist above, and the sheathing (especially if it was 3/4" or something beefy) might hold the whole assemblage stiff. I've definitely had engineers tell me not to worry about a small gap here or there on the basis that "the ply will tie all that together".

    I've also seen where a wet piece of wood (sopping wet PT, in one case) was really constrained from moving on both sides, being attached to concrete. When I checked it out at the end of the job, it had shrunk and sort of ended up as a torn, ropey mass. It was no longer a solid 2x10, but it still was tying things together. I think there is more of that "torn ropey mass" stuff going on in solid lumber structures than a lot of people realize.
    “It is difficult to get a man to understand something, when his salary depends on his not understanding it.” - Upton Sinclair

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