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  1. #11
    Join Date
    Jun 2011
    Posts
    208

    Default Re: Popping Drywall Nails - Suggestions Please

    Well, I've done some digging too, and I stand by my initial position; smooth shank nails driven into green wood LOOSE their holding power as the wood dries, everything else being equal.

    Here's a web page from your US Department of Agriculture, Forestry Service, Forestry Products Laboratory:

    http://www.fpl.fs.fed.us/products/pu...00&header_id=p

    Download chapter 8 of their "Wood Handbook" and on page 3 of Chapter 8 it says:

    Effect of Seasoning
    With practically all species, nails driven into green wood and pulled before any seasoning takes place offer about the same withdrawal resistance as nails driven into seasoned wood and pulled soon after driving. However, if common smooth-shank nails are driven into green wood that is allowed to season, or into seasoned wood that is subject to cycles of wetting and drying before the nails are pulled, they lose a major part of their initial withdrawal resistance. The withdrawal resistance for nails that are driven into wood that is subjected to changes in moisture content may be as low as 25% of the value for nails tested soon after driving. On the other hand, if the wood fibers deteriorate or the nail corrodes under some conditions of moisture variation and time, withdrawal resistance is eratic; resistance may be regained or increased over the immediate withdrawal resistance. However, such sustained performance should not be relied on in the design of a nailed joint.



    In addition, look at this report from the Virginia Polytechnic Institute dated July, 1964. It claims that the style of nail used has an important influence on withdrawal resistance:

    http://unitload.vt.edu/research/WOODBulletin-53.pdf

    On page 3, it says:

    It is a well known fact that plain-shank nails lose as much as four-fifths of their initial holding power during seasoning of the nailed lumber, while properly threaded nails retain or slightly increase their initial greater holding power under identical conditions.

    This report purports to show that, unlike smooth shank nails, threaded nails driven into wet wood increase their withdrawal resistance as the wood dries. However, if you look at "Table 1" on the last page, the highest withdrawal resistance recorded is for a threaded nail driven through oak that had a 33.6 percent moisture content and was allowed to dry for 5 weeks. In that case, the anomolous 907 pound withdrawal force (which was nearly twice it's initial withdrawal resistance) was attributed to rusting of the nail shank inside the wet wood.

    I certainly can't explain why threaded nails would behave differently than smooth shank nails in wet wood, but it's clear from the test results that rusting of the nail shank is a critical factor in determining the force required to pull the nail out once the wood has dried.

    J. Kirk: Please don't read my posts.
    I don't read yours.

    Ordjen: You said:
    Ceiling pops are more prevalent because of the downward weight of the drywall.
    You'd think that ceiling pops would be less prevalent if gravity is helping to prevent them. Where am I screwing up in my thinking here?
    Last edited by Nestor; 07-01-2011 at 03:39 AM.

  2. #12
    Join Date
    Aug 2007
    Location
    The Great White North
    Posts
    4,045

    Default Re: Popping Drywall Nails - Suggestions Please

    Quote Originally Posted by Dev View Post
    I recently moved into a 1960s built home (Silver Spring, MD). I see that nails are popping out from walls and ceiling throughout the home. A small bulge appears and in weeks, it cracks open, exposing nail head. I used a punch, drove them in (just a tap). Nails appear to be very lose in their holes.

    I hear random(5-15 per 24hrs) noises all the time, more if I change thermostat setting (say to 68 from 73 or hot day to cold night). Noises are like a snap/cracking whip or like when you try to remove old, stuck nail using claw hammer from wood or like expansion/contraction sounds of office buildings with large glass & aluminum side-walls.

    I see attic insulation is weak (fiber glass, blown in, has compressed/settled to about 1.5 - 2 inches, bald at places) & not ventilated well, gets super hot inside.

    I am inclined to think that temp variation, noises & nails popping are connected.

    I am thinking of using drywall screws every where, options are:
    1. Drive popped nails back in, put a new drywall screw, like 2" from nail.
    2. Remove nail, as they pop, drive a matching sized screw into same hole.

    I wish to have all problems solved...
    any suggestions much appreciated, thanks
    Instead of using the nail hole --- drive the screw above or below the nail and then remove said nail..
    "" an ounce of perception -- a pound of obscure "
    - Rush

  3. #13
    Join Date
    Jun 2011
    Posts
    2

    Default Re: Popping Drywall Nails - Suggestions Please

    Thanks a lot everyone, for all the information & experienced thoughts.

    Solution I am going with - fastening with screws, 2" away from popping nail.
    Nails are loose enough to be pulled out easily using pliers.
    Boards are 1/2" gypsum.

    Please comment on attic ventilation when you get a chance:
    Larger attic: 45ft x 25ft - 2 gable vents, no soffit/inlet.
    Smaller attic: 25ft x 25ft - 1 gable vent, no soffit/inlet.

    I am thinking of installing 6" round inlets on the eaves (from venymyhouse_com), about 12 on larger attic & 6~8 on smaller one.

    Thanks again,
    Dev

  4. #14
    Join Date
    Dec 2010
    Location
    Houston Texas
    Posts
    2,358

    Default Re: Popping Drywall Nails - Suggestions Please

    Didn't I say that already?

    If you can, ridge venting with continuous eave venting is optimal. Other venting systems lead to hot spots, which you may or may not care about.

  5. #15
    Join Date
    Jun 2011
    Posts
    208

    Default Re: Popping Drywall Nails - Suggestions Please

    I find that lots of people in the southern USA try to increase the amount of attic ventilation to allow the hot air out of their attic in summer in an effort to help keep their house cooler.

    If that's the case here, ignore the rest of this post.

    Where I live, insufficient attic ventilation can result in an inch of frost forming on the underside of a roof over the course of a winter (and I saw a picture of one house with 3 inches of frost under it's roof). That frost causes no problems...until spring, when it melts and drips off the roof rafters onto the ceiling insulation below. Insulation works by keeping air stagnant and preventing convective currents that would otherwise form. Unfortunately, that also means that wet insulation takes forever to dry out because of the lack of air circulation through it, and wet insulation in contact with wood joist leads to wood rot. And, on top of it all, the vapour barrier below the insulation will help keep the ceiling dryer than it would otherwise be, and that diminishes the urgency of the problem in the eyes of the homeowner. So, you have a "perfect storm" of problems arising from insufficient ventilation that can do real serious damage to a house.

    The first thing to determine is whether or not you need more attic venting.

    Go into you attic on the coldest day of the year and look for frost or condensation anywhere on the underside of the roof sheathing. Look for dirty spots on the insulation cuz if there is any condensation forming airborne dust will stick to the wetness and it'll be deposited on the insulation by the dripping water. If you don't see any frost, condensaiton or dirty spots on the insulation, then check to see if you have any ice damming on your eves. If you don't see any of that either, then you don't need any more attic ventilation than you already have.

    Ridge vents with soffit vents are only THEORETICALLY optimal. They rely on the convection of warmer air out the ridge vent and colder make up air in the soffits to work as they're supposed to. However, you have as many dead calm days in the winter as you do in the summer, and MOST of the time there's some wind outside. That wind creates a higher pressure on one side of the house than the other and you get cold air coming in the soffit vents on one side of the attic and warmer air being pushed out the soffit vents on the other side of the attic. Just pop up to your attic for a smoke on any winter's day and you'll see that the smoke doesn't rise gracefully up to the ridge drawing cold air in behind it through the soffits. It gets swirled around in every direction at once by the air currents in the attic caused by wind coming in the soffit vents.

    My feeling is that the more holes you have in your attic that allow air in and out, but not water, the better. That's because not all of those holes will be working all the time. For example, where I live, it's common to have a foot or so of snow accumulate on your roof in the winter, and that pretty much renders a ridge vent useless. That's when you discover that you ALSO need gable vents. But, the gable vents will only be effective when the wind is blowing the right way. So, in my view, the more holes you got, the better. Once the warm air rises into your attic, it's of no more benefit to you, and it's better to get rid of it as fast as possible than to let moisture condense out of it.
    Last edited by Nestor; 07-01-2011 at 02:13 PM.

  6. #16
    Join Date
    Mar 2008
    Location
    nova scotia, canada
    Posts
    1,522

    Default Re: Popping Drywall Nails - Suggestions Please

    in regards to attic ventilation. the attic must be treated as a cold zone or condititoned as outside space which means unheated and direct venting to the outside

    in canada the national building code states that 1sq ft of ventilation must be provided to 150 sq ft of ceiling space. this can be achieved by installing soffit ventilation with ridge venting or gable vents.

    however, it has been seen by many contractors that having gable end vents with soffit vents can actually create moisture problems. in heavy rain and wind conditions water can enter the attic space by being wind driven in. because of this, more and more in new construction the almost never see a true "gable end vent" fake ones are installed just for the look of a end vent.

    truss uplift can be cause drywall cracks at the joint between the ceiling and wall. this is caused by temperature differences between the top and bottom chords of the truss which then makes it so the top chord will want to pull up on the bottom chord, thus pulling on the ceiling which causes the drywall to crack even have nail pops. more and more drywallers are becoming aware of this problem and are now adopting installing the top row of screws 7" down from the ceiling, this allows the sheet to flex and not be brittle reducing the chance of the seems breaking and screws popping.

    with your house being older without actually being in your house and seeing what you have for structure it can be several things all working together to create problems
    fire up the saw and make some dust

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