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Drywall screws popping on wall.......


grantiman's Avatar
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01-19-11, 08:57 AM   #1  
Drywall screws popping on wall.......

I'm re-doing my bathroom, I see about 10 drywall screws started to push out of the wall. With a knife I took off the paint and plaster covering the screws, these screws were very close to the surface. I screwed them deeper into the wall and cleaned out the screw slots. Someone told me not to re-plaster over the old screws, they will pop again. Should I take the old screws out and put in new drywall screws? Thanks........

 
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01-19-11, 09:20 AM   #2  
Screws as a rule should not pop unless they weren't fully screwed in. They should just dimple (but not tear) the paper when properly set. Now..if they were too short or didn't hit a stud..I guess they could pop off the mud.

I'd probably remove one and check the length, them maybe take a piece of coat hanger or a thin drillbit and check for solid wood behind.

Is this possibly an old house where sheetrock was installed over old plaster and lath?


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01-19-11, 09:51 AM   #3  
This was a new built house, only around 15 yrs old. The screws are in the studs, they were only loose and close to the surface. I screwed them further into the wall and they tightened right up. Is it ok to plaster over these old screws or should I replace them? Thanks....

 
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01-19-11, 10:05 AM   #4  
Well...I was always told that with nail pops (much more common before screws came out) you should put a screw in just above or below the problem. Then a light sanding over the area, then some spackle should be fine.

Thats what I've been doing for 25 yrs since owning homes...


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01-19-11, 10:14 AM   #5  
I always put mud over top but this has only happened to me two or three times in one bathroom

Been six years, so far everything staying the way I put it

 
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01-19-11, 01:39 PM   #6  
I'd add a screw near each screw pop, not sure that I'd trust the screw that's already backed out some. It's probably ok to leave the old screw once it's screwed back in, the new screw should insure that the old screw will stay put. If you remove the old screws, don't reuse that hole, rescrew a couple of inches up/down so the screw has fresh wood to adhere to.


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01-19-11, 02:06 PM   #7  
I can't remember what exactly I did anymore now that I've been thinking about it, I may have used the same hole but replaced the screw with a longer one

 
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01-19-11, 07:20 PM   #8  
We had screw pop problems two years ago on new construction homes here in the mountains. It rained every day for a month. Sheetrock was installed with a high moisture content, taped and mudded. I spent the fall contracting to builders going in houses and resetting screws (sometimes longer) and patching holes. Houses looked like a leopard when I left. Of course I don't paint

 
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01-20-11, 10:14 PM   #9  
Grantiman:

Tightening up the existing screws is OK, but if it were me I'd also put another drywall screw both an inch or two above and below each one that popped. And, there's good reason for doing that.

If you do that, what's happened won't happen again unless it happens on different screws, perhaps in a different area of your house. This idea that those screws "backed out" simply isn't true. Same with the idea that if the screw popped, it'll pop again. Both of those opinions are generally true for nails, but not for screws, and the reasons will be clear if you read the rest of this post and a paper written by Dr. Stephen Smulski in 1996.

Wood is a natural material and shrinks as it's moisture content decreases. It's not actually the wood itself that shrinks as it dries, it's the wall thickness of the wood cells that gets smaller. Since wood cells look like long cylinders closed off at the ends and about 80 times longer than they are in diameter, there are vastly more wood cell walls as you go across the grain of wood than there are along the grain of wood. Consequently, since it's only the wood cell walls that get thinner as the wood dries, the amount of shrinkage that occurs is very much greater ACROSS the grain than it is along it's grain. In most cases, wood shrinkage along the grain is small enough to be disregarded, but there are construction problems (one of which is called "truss uplift") that are caused by wood shrinkage and swelling ALONG the grain of wood.

What most likely happened in your case is that the lumber used for construction was stored outdoors, and got rained on during construction. Consequently, the lumber at the top of the lift got wet, and some of those studs were used in your bathroom wall. Over the next year or two, those wet wood studs dried out and shrank, so that a gap developed between the back or the drywall and the front of that formerly wet wall stud.

(Now, this is where I fly off on a tangent. Wood is relatively soft, and it's not difficult to prevent that contraction from occuring in wood as it dries. If you use a screw instead of a nail, then the threads of the screw will hold the wood in it's swollen position as it dries, thereby preventing the wood right around the screw from shrinking. But, that effect is very local. If you take the drywall off those studs in your bathroom, what you'll see are small bumps (about 1/4 inch in diameter) where the dried wood "sticks out" from the front of the stud. The top of those bumps are where the face of the stud originally was.

Now, the exact same thing happens when you nail plywood or lumber subflooring down to the tops of wet floor joists. As those joists dry out, they shrink and a gap develops between the top of the floor joist and the underside of the subfloor. But since nails don't have any threads to hold the wood in place as it dries, you don't get those bumps holding the wood in it's swollen position around each nail. The result is a squeeky floor. That's because the squeek actually comes from both the nail and the subfloor vibrating as they rub against one another when you walk on the floor.)

And this is where I come back to the subject at hand...

So, what you have are swollen bumps around each popped drywall screw. Those bumps hold the drywall about 1/64 to 1/16 inch away from the face of the studs. All someone has to do is lean against the wall slightly with their hand (while cleaning or something) and that will press the drywall tight against the studs and cause the joint compound to break off the tops of nearby drywall screws.

To solve the problem, you need to not only tighten the popped drywall screws, but also eliminate any tiny gap behind the drywall caused by the bumps in the wood where the drywall screws are. Typically, you put one drywall screw above and below (or on each side) of the offending screw to press the drywall back against the stud face. Then, there's no reason for any of those screws to pop again now that the wood is dry and won't shrink any more.

Dr. Stephen Smulski used to teach at the University of Massachusettes in the Building Materials and Wood Technology Program. That program is now called the Building and Construction Technology Program, and Dr. Smulski has since moved on and started his own wood failures consulting company. You can find more papers on wood construction and wood science on the U of Mass BCT web site at:

UMass Amherst: Building and Construction Technology

(Just click on the "Publications" link and then click on the "Publications by Title" link to see a list of titles sorted alphabetically.

While teaching at the U of Mass, Dr. Smulski wrote a paper that explained many common house problems (like drywall nail pops and squeeky floors) in terms of wood science and customary construction methods. That paper is called "Detailing for Wood Shrinkage" and you can find a copy of it here:

Minimizing Wood Shrinkage Problems

If you read that paper, you'll know what causes drywall nail or screw pops, and knowing what caused them and why makes knowing how best to fix them a simple matter of reasoning.

Hope this helps.


Last edited by Nestor; 01-20-11 at 10:46 PM.
 
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01-21-11, 10:39 AM   #10  
Gunguy:
"I was always told that with nail pops (much more common before screws came out) you should put a screw in just above or below the problem."
Screw threads hold swollen wood in place and prevent it from shrinking as it dries. The result is a "bump" in the stud face immediately around the drywall screw. So, if this was a popped drywall NAIL, you'd be correct cuz there probably wouldn't be a bump to contend with. But, these were drywall SCREWS that will leave a bump. So, to do a Cadillac job here, it's really better to put a drywall screw on both sides of each popped screw to hold the drywall snug to the stud face of both sides of the bump. Typically, the only time you find those bumps around nails is when the wood was so wet that the nail rusted inside the wood, and it's the formation of that rough rust layer that gripped the wood and prevented it from sliding over the nail as it dried and shrank.

Marksr:
"I'd add a screw near each screw pop, not sure that I'd trust the screw that's already backed out some. If you remove the old screws, don't reuse that hole,..."
The screw didn't back out. The screws felt like they were a little loose when the poster tightened them up, but that's because the wood shrank away from the screw thread, thereby lessening the wood's grip on the screw, and making it seem loose. There's no problem tightening up the popped screw in the same hole. Now that the wood is dry, there won't be any more shrinkage, and the popped screw won't do an encore performance. Neither will any of the new screws added now that the stud has stopped drying (and hence, shrinking).

Chandler:
"It rained every day for a month. Sheetrock was installed with a high moisture content, taped and mudded."
So, you figure it was the moisture content of the drywall that caused the problem?

As DIY'ers we deal with a very broad range of problems; everything from exterminating insects to repairing appliances, installing ceramic tile to hanging doors. It's because DIY work requires fairly detailed knowledge over an extremely broad spectrum of subject matter, no one can know everything. The saving grace, however, is that it's through Q&A forums like this one that we exchange ideas and information with each other, and in that way we all benefit. We ALL learn from each other in here. I know I've learned a lot since registering on this board.


Last edited by Nestor; 01-21-11 at 01:02 PM.
 
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01-22-11, 04:28 PM   #11  
Nestor, yes, high moisture content of drywall materials stored in non-climate controlled buildings, transported (although covered) to jobsites in moist air, and installed immediately without any accliamation.............I'd say high moisture content sheetrock. Framing and dry in was done before the monsoon hit, so the framing lumber was dry.
I agree if all your criterion are met, you will have shrinking wood, but it didn't happen in this case. Thanks for the dissertation, however.

Oops, forgot. Georgia Pacific at that time was making sheetrock as fast as they could and shipped it almost as quick as it was dry in the mill. Didn't help not curing in climate controlled areas first.

 
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01-24-11, 08:08 AM   #12  
Thanks for all the advice, I learned a lot today. I may have to correct myself, my wall had a lot of bumps with cracking around where the screws are in the sheetrock. I should have worded my question better, what I ment by popping was the screws are beginning to push out on the wall with cracking around the screw hole. Neverless I'll put extra screws back in the wall before I re-paint it, thanks for all the help. I have another problem with the same room if you would like to read my thread, "Have belly in wall, can I plaster it?" Thanks......

 
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