# Trouble with screws bulging



## Wimpy65 (Dec 17, 2013)

Hello everyone! I'm new to Drywall Talk and this is my first post (so be gentle). I've been in the drywall trade for 30 years, mostly as a finisher. I guess that makes me an old dog, but I'm still learning new tricks. I've recently had trouble with screws swelling long after the job is completed. This week I got a call back for a job I finished last May. The problem is the screws in the field are protruding and need to be scraped off to be level with the surface again. I've seen this problem on some other recent jobs. 
Here is the run-down of what I know:

- The screws were coated (3 to 4 coats) with USG All-Purpose
mud (green lid/purple lid).
- They were flat and smooth after I sanded them
- I have used the same method for years with no trouble like this
While I would like to blame wet lumber, I wonder if something else is going on because framers have used wet
lumber for years without this problem showing up - The job was warm when I worked there and had central heat before cool weather.
- The drywall used was lightweight drywall (the builder thinks this may contribute to the problem); I've noticed some of you
don't like the new lightweight drywall and wonder if you have had similar problems. If this problem persists, I may have to use metal battens (if I can pass the cost along)Thanks in advance for any advice you can send my way! I have enjoyed the information I have gleaned here so far (and the playful banter) and look forward to your thoughts on my situation.


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## jcampbell (Aug 26, 2012)

Did the board shrink? Is there an air exchanger/dehumidifier running?


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## boco (Oct 29, 2010)

Board was swollen now its shrink. Dehumidifier and fans would prevent this.


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## Wimpy65 (Dec 17, 2013)

I don't know if the board was swollen or not. Do I need to run a dehumidifier as I hang the board? Seems like it could just pick up moisture after I'm finished. What happens if the central heat is not hooked up? Is the builder correct; is this a problem with the lightweight drywall? Thanks!


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## cracker (Nov 3, 2013)

If you glued..board was pulled in as the high moisture wood dried...screw stays in the same place because as wood shrinks in does not take the screw with it. Funny how wood is like that!!...make sure the wood you hang on is less than 12-15% moisture


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## Wimpy65 (Dec 17, 2013)

Wow! So, I should check the lumber's moisture content? Do you also check the drywall's moisture content? What percent should the drywall be at? Today's drywaller has to go high tech. This hadn't happened with the regular drywall (in the good old days), just this lightweight drywall.


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## Magic (Feb 20, 2014)

Thats scary Wimpy. The screws are still tight?


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## BOBTHEFIXER (Oct 28, 2013)

Welcome to drywalltalk,

This is a long shot but if its not everywhere and never happened to you before, do you think it might be flooring guys banging the floor or the doors while installing them or the baseboard?


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## Wimpy65 (Dec 17, 2013)

Yeah, it is a little scary. The sheets are still tight. I think about how many jobs I've done with this lightweight drywall and wonder how many will come back to haunt me.
I have seen on other jobs, but have not gotten any call-backs on those. I'm not sure about carpenters banging around to cause this. Something to look into. 
Has anyone else had this problem? Is the swelling sheet problem something exclusive to lightweight board? I'm not sure I can even get regular drywall around here anymore.


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## ell (Jan 24, 2009)

*screws bulging*

Is it on the clgs ,walls or both ,possible screw gun depth to deep or worse yet cordless drill


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## Wimpy65 (Dec 17, 2013)

Walls & ceilings, but mostly ceilings. What does the cordless screw gun do? The hanger did use a Makita cordless.


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## Wimpy65 (Dec 17, 2013)

Hey Cracker, what kind of moisture meter do you use? I may have to invest in one. Do most of you guys take moisture readings of drywall & lumber?


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## moore (Dec 2, 2010)

http://www.paintsource.net/pages/solutions/new construction/nail_pops.html


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## Wimpy65 (Dec 17, 2013)

Thanks Moore, that is a helpful link. I'll have to pass that along to the builder. Do you run dehumidifiers on your jobs? Seems like that wouldn't work too well until the lids are drywalled. I guess that dehumidifiers would need to run to lower moisture in the drywall, as well. Oh for the good old days when lumber was dry!


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## Magic (Feb 20, 2014)

You also said you finished it in May. Do you remember if heat was on? I've had weird problems when finishing jobs that time of year with no heat. I'm sure you have too. Did u have heat?


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## Corey The Taper (Mar 18, 2014)

Ive been getting alot of those in the entrances where theres the most stress but I believe its because theres no heat in the house and when there its the propane kind so it gets shut off when we leave


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## thefinisher (Sep 2, 2011)

There is a lot of things that will cause a screw to pop. Wet lumber, even a little bit will do it. Ceiling screws like to pop when flooring gets put in. screws around trim like to pop when trim is installed. basically any movement or source of wetness will pop them! Only way to get around this is to glue the board and put one screw every other stud or so then wait for glue to cure then back the screws back out. Of course that is only for walls. Of course most people still put 3 in the field on each stud. If you build a house, the screws are going to pop at some time.


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## cracker (Nov 3, 2013)

Wimpy65 said:


> Hey Cracker, what kind of moisture meter do you use? I may have to invest in one. Do most of you guys take moisture readings of drywall & lumber?



any brand works good....what wont work is when you tell your GC he has wet wood....getting him to understand does not work:furious:


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## moore (Dec 2, 2010)

thefinisher said:


> If you build a house with wood, the screws are going to pop at some time.


.....:yes::yes::yes:


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## Wimpy65 (Dec 17, 2013)

We were finished by the end of May, so no heat was needed at that point.
Our building codes require screws every 16", so I can't get away with removing screws after the glue sets. 
Yes, there will be some screw pops, but this is unusual.


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## cracker (Nov 3, 2013)

What this industry needs is a fastener that holds the drywall independently from the connection to the wood stud!!!...but that's not going to happen because drywall is not structural...


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## drywall guy158 (Dec 31, 2009)

I always warn my customers before I do a job and tell them if there going to get any screw pops there going to show up after the first winter there moved in and the furnace has been running all winter. winter and spring = low humidity and things dry out. and I do check lumber with a moisture meter if i'm going to be hanging the board. I give NO warranty on screw pops ! its in every contract. I cant warranty something I have no control over


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## moore (Dec 2, 2010)

cracker said:


> What this industry needs is a fastener that holds the drywall independently from the connection to the wood stud!!!...but that's not going to happen because drywall is not structural...


https://www.youtube.com/watch?v=-IfYuNnRLgU


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## boco (Oct 29, 2010)

The end of last may there was quite a bit of rain. I remember driving an hour away into mountains to tape a cabin. I had the HO buy a dehumidifier for that one. Kinda funny but I started using dehumidifiers 100% of the time around the same time the lightweight rock started coming around. New rock sucks and lumbers all wet. Just not a good combo


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## cracker (Nov 3, 2013)

moore said:


> https://www.youtube.com/watch?v=-IfYuNnRLgU


Yes there is RC1...without adding an extra inch to the walls???


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## Magic (Feb 20, 2014)

After you scraped and re-coated did you push on the rock to see if there is any movement?


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## Mudstar (Feb 15, 2008)

What I've been finding is that some of the paints out there are soaking in to the compounds and it swells and drys, humping it out, what a pain in the a$$ that is to fix.


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## VANMAN (Jan 14, 2011)

Mudstar said:


> What I've been finding is that some of the paints out there are soaking in to the compounds and it swells and drys, humping it out, what a pain in the a$$ that is to fix.


Fix what?
After I'm finished its some other f*ckers problem!:thumbsup:
Don't do call backs ever!:thumbup:
Its out of my hands what goes on with twisting/heat and the rest that can happen!!
I have seen some crazy sh*t happen that makes u wan't 2 cry! But its still not my problem! Wet timber and board,then heat is not a good combination!!:furious:


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## jcampbell (Aug 26, 2012)

Mudstar said:


> What I've been finding is that some of the paints out there are soaking in to the compounds and it swells and drys, humping it out, what a pain in the a$$ that is to fix.


I have found that also . Was using certainteed lite weight blue box . I go all red now . Was nice to sand tho.


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## Magic (Feb 20, 2014)

Wonder if we need to switch to mid weight during the wet no heat months.


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## cracker (Nov 3, 2013)

this was on wconline




Yes, gypsum board does shrink due to changing heat and humidity levels. But don’t jump to conclusions. 

We review articles, reports and technical documents from a variety of sources at the Gypsum Association, and some contain some “unique” conclusions. An article that recently appeared in a national periodical discussing “shrinking gypsum board” falls squarely in that category.

The article discussed “nail pops” and theorized that the cause of the pops was “shrinking” gypsum board. According to the article, the board absorbed moisture as the result of exposure to high humidity conditions during transit and storage. Then, after installation in a conditioned environment, the board shrank, thus causing the heads of the application fasteners to become exposed.

It is an interesting supposition. Unfortunately, it is completely incorrect on a number of levels. Here’s why.

*Getting the numbers straight*

Virtually all common building materials expand and contract as the result of two primary physical influences: thermal expansion and hygrometric expansion. Thermal expansion occurs when a material is exposed to heat. It can be quantified for a solid object by identifying its Thermal Coefficient of Linear Expansion (call it TCLE, for short). Hygrometric expansion occurs when a material absorbs moisture, including water vapor.

This characteristic is particularly true for materials of organic origin and is usually expressed by quantifying the Hygrometric Coefficient of Expansion (let’s call it HCE, for short).

Gypsum board exhibits both thermal and hygrometric expansion characteristics. It has a TCLE of 9.0 x 10-6/in. and a HCE of 7.2 x 10-6/ % RH. In lay terms, that means that an inch of gypsum board will expand 0.000009 inches when the temperature of the board is increased by one degree Fahrenheit. Likewise, an inch of gypsum board will expand 0.0000072 inches when the relative humidity in the area of exposure is increased by one percentage point.

Materials with higher TCLE or HCE coefficients expand and contract due to changes in temperature or moisture to a greater extent than materials with lower coefficients. Comparatively, the TCLE coefficient for steel is somewhat less than that of gypsum board and the coefficient for aluminum is significantly greater. Simply stated, when exposed to heat, a gypsum panel will expand slightly more than a steel panel, but less than an aluminum panel. Mercury has a very high TCLE, which makes sense when you think of its traditional use in thermometers.

*Digging deeper*

So, if gypsum board can expand and contract, why doesn’t the movement cause fastener pops? Essentially, there are two reasons. First, an individual sheet of gypsum board does not expand or shrink very much (note the numbers above; they are not very large). Second, fastener pops are a function of stresses placed on the fasteners from myriad other sources, all of which are significantly greater than the thermal or hygrometric stress placed on a board. 

The first concept can be most readily explained by simple math and comparative analysis using the HCE for gypsum board. Since the board in question was installed in the southeastern United States, let’s assume that it was transported, stored and installed in a hot, humid Georgia summer with a relative humidity of 90 percent. Then, let’s assume a cold, dry winter with a relative humidity of 20 percent. That’s a swing in relative humidity of 70 percent over six months, easily a worst-case scenario. 

Also, note that gypsum board is isotropic, meaning that it moves uniformly in all directions when it expands and contracts. As a result, a board will expand from side-to-side and top-to-base at the same rate that it expands from back face to front face. 

Take the HCE for gypsum board of 0.0000072in./% RH; multiply it by 70 (using an integer for the percentage change in relative humidity); multiply it by 0.5 (for the thickness of the board) and you arrive at a figure of 0.00025, or 25 ten-thousandth of an inch. That is how much a layer of 1/2-inch-thick gypsum board will shrink from front to back when exposed to a decrease in relative humidity of 70 percent - not much of a change and not perceptible to the naked eye.

Now assume that the fasteners in question are either standard drywall nails – manufactured to ASTM C 514 – or standard drywall screws – manufactured to ASTM C 1002. Per standard, ASTM C 514 nails have a head that is a minimum of 0.015 inches thick and ASTM C 1002 screws have a head that is a minimum of 0.02 inches thick, both measurements taken at the edge of the fastener. Compare the gypsum board shrinkage to the fastener head thickness and you quickly arrive at the conclusion that even if the board did shrink due to an extreme change in relative humidity, the total shrinkage was less than 2 percent of the thickness of the head of the thinner-headed fastener; movement that is undetectable if the fasteners are properly installed and not sufficient enough to expose the head of the fasteners. The movement also is less than the thickness of the face paper of the board and less than the suggested thickness of the joint treatment that is applied to the board.

*Wood you have guessed?*

So what causes fastener pops? The biggest culprit is lumber that is installed when it is still “wet” and does not attain environmental equilibrium until well after the gypsum board has been applied. Most wood industry documents recommend (and increasingly most building codes require) that the moisture content of framing lumber not be in excess of 19 percent at the time of installation. Even if installed “per standard,” lumber that shrinks to a 6 percent moisture content (a common winter environment moisture content for lumber) will decrease by almost 5 percent in cross-section. For a properly manufactured 2-x-4, that’s more than 1/8 of an inch of shrinkage. 

Furthermore, as the lumber shrinks, it places pressure on the shank of the fasteners used to attach the gypsum board. That pressure, coupled with the receding stud, forces the fastener out from the stud and causes the head of the fastener to “pop” out from the surface of the board. Use of over-long fasteners increases the shank area – thus increasing the area where pressure may be placed on the fastener – and exacerbates the problem, as does the use of plain shank nails. Ring shank nails and screws are less affected.

Worker error is also another prime cause of fastener pops. Fasteners that are not properly seated or that completely miss the framing member; use of the wrong-size fastener; and not holding the board tightly to the framing members when it is installed all can cause fastener pops. Fastener pops can also occur in metal framing; however, unlike wood framing fastener pops - which are most often a function of the moisture content of the lumber - metal framing pops are most often attributed to worker error and are caused by fasteners that are not properly seated in the metal studs, or by the use of fasteners that have a thread pattern that is too large for the thickness of the metal studs. Building stresses, in particular the downward pressure placed on walls by truss movement, can also aggravate the problem.

Based on the description of the situation as it appeared in the original article, it is difficult to determine exactly what caused the rash of fastener pops that occurred. To be fair, the author may not have been able to obtain all the background information on the situation – information about stud moisture and application conditions that might have allowed a different conclusion. However, what is clear is that the inference that was expressed in the article was incorrect and that gypsum board doesn’t shrink as claimed.


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## Magic (Feb 20, 2014)

Thanks cracker. Im saving that artical.

Everyone wants their job done asap. Most every callback I get is due to shrinkage. I've always fixed the pops and chit because I care. And I want every job my builders get!! Lol


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## boco (Oct 29, 2010)

Magic said:


> Wonder if we need to switch to mid weight during the wet no heat months.


 If you are using lightweight now You need to get moisture meter, dehumidifier, 220 heaters and lots of fans. Also waiting a day or 2 after final coat to sand. .The problem with lightweight is the delayed shrinking that occurs after it fully dries. i have been using a ez sand and plus 3 to skim for about 3 years now not for houses but condos. Start on Mon prime on Fri. Havent had any issues at all other then an occasional crack in angles where it meets the beads. another thing I like to do is keep the temperature at around 68 degrees. Too much heat and mud shrinks too little it cracks. Run lots of fans


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## boco (Oct 29, 2010)

i dont agree with article sheetrock swells up like a beyatch. If you want an example go to lowes pick up some board store it outside and install it. Make sure your attaching it to steel so you know its not thw lumber . Tape then come back and check it out 6 months later.


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## cracker (Nov 3, 2013)

boco said:


> i dont agree with article sheetrock swells up like a beyatch. If you want an example go to lowes pick up some board store it outside and install it. Make sure your attaching it to steel so you know its not thw lumber . Tape then come back and check it out 6 months later.



He did not say it does not swell. Just the swelling is a lot smaller than most plp think. I think wood plays a lot larger roll in the whole house "nail pops" plp are talking about, and if it shrank that much don't you think there would be tapes pulling lose? If the board shrank and poped the heads up +/- an 1/8" don't you think it would of also lost the same across the L and W of the board, and not just in the 1/2 core? I say test it all! Make sure you get a 20%mc+ stud and glue it put a few screws in it...watch the screws rise up. Its not the glue, its the combination of gluing on wet wood. Do the same with no glue...watch the gap form between drywall and stud. Im just hoping for a better tomorrow for all of us..with less call backs


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## Wimpy65 (Dec 17, 2013)

I like the idea of the tests. I have a nearby Lowes that does store the drywall outside, so it should have picked up moisture. I'll test wet studs & wet drywall.
I agree with you Boco about running heaters & lots of fans. I usually run both, but I think I'll throw the dehumidifier into the mix now.

Thanks so much for all the helpful thoughts & ideas! I figured I could count on the DWT gang to help me out. :thumbup:


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## ell (Jan 24, 2009)

*screws bulging*

If they use a cordless gun I find theirs no depth adjustment or clutch so the screw has to be set just right so the chances are good they might have been set a little to deep and with the weight of the board and spackle softening the paper at the screw head could be enough to make them pop. I would think if it was a moisture problem their would me more wrong than just the screws.but thats just my opinion


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## drywallninja (Apr 28, 2013)

Wimpy, are you using glue?


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## Wimpy65 (Dec 17, 2013)

Hi Drywall Ninja,

Yes, the drywall was installed with screws every 16" and drywall adhesive, as required by our building code.
Now the builder is concerned that the pops might return after I repair them. I would think whether it be joint compound or wood swelling/shrinking, it would be done by now (1 year after drywalling).


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## Corey The Taper (Mar 18, 2014)

Wimpy65 said:


> Hi Drywall Ninja,
> 
> Yes, the drywall was installed with screws every 16" and drywall adhesive, as required by our building code.
> Now the builder is concerned that the pops might return after I repair them. I would think whether it be joint compound or wood swelling/shrinking, it would be done by now (1 year after drywalling).


I just went to look at a job alit of the screws were bulging like 3/8s out could it be a framing foundation problen. Also alot of corners cracking some moved about half an inch this is a house that has been up only a year. Random cracking over doors where there was a sheet from wall to wall.


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## moore (Dec 2, 2010)

Corey The Taper said:


> Random cracking over doors where there was a sheet from wall to wall.


Diagonal cracks next to the interior doors??


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## Corey The Taper (Mar 18, 2014)

moore said:


> Diagonal cracks next to the interior doors??


Yes from the corner of the door moldings to random spots to the ceilings. This was a house done by the gc I do alot of work for before I started doing his drywall I can see every flat and crossbar. Some of the screws bubbled like almost a water blister all the beads are showing some of them cracked some just you can tell they cut corners.


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## jcampbell (Aug 26, 2012)

Corey The Taper said:


> I just went to look at a job alit of the screws were bulging like 3/8s out could it be a framing foundation problen. Also alot of corners cracking some moved about half an inch this is a house that has been up only a year. Random cracking over doors where there was a sheet from wall to wall.


Sounds like an Alberta house built overnight.


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## Corey The Taper (Mar 18, 2014)

Well im gonna do it for free I guess the gc asked for a "favor" since he gives me all his work instead of getting the hacks who did it. Im not sure if its for free though we never discussed payment though lol


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## Corey The Taper (Mar 18, 2014)

Also the screws are bulging from behind the tape ive never seen that before it must be a framing/foundation problem


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## Magic (Feb 20, 2014)

There aint much to screw to when you get a diagonal crack by a door.


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## Corey The Taper (Mar 18, 2014)

Whats that mean i dont want to fix **** if its just gonna keep on getting worse I told him to get it inspected before hand


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## moore (Dec 2, 2010)

Corey The Taper said:


> Yes from the corner of the door moldings to random spots to the ceilings. This was a house done by the gc I do alot of work for before I started doing his drywall I can see every flat and crossbar. Some of the screws bubbled like almost a water blister all the beads are showing some of them cracked some just you can tell they cut corners.





Corey The Taper said:


> Well im gonna do it for free I guess the gc asked for a "favor" since he gives me all his work instead of getting the hacks who did it. Im not sure if its for free though we never discussed payment though lol





Corey The Taper said:


> Also the screws are bulging from behind the tape ive never seen that before it must be a framing/foundation problem





Corey The Taper said:


> Whats that mean i dont want to fix **** if its just gonna keep on getting worse I told him to get it inspected before hand


You are now a drywall contractor Cory! Have at It!!! :thumbsup:


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## drywallninja (Apr 28, 2013)

Wimpy65 said:


> Hi Drywall Ninja,
> 
> Yes, the drywall was installed with screws every 16" and drywall adhesive, as required by our building code.
> Now the builder is concerned that the pops might return after I repair them. I would think whether it be joint compound or wood swelling/shrinking, it would be done by now (1 year after drywalling).


Applying glue and then putting a screw or however many your code requires may unfortunately be your problem. I've found that anywhere you put a screw where you've applied glue, more than likely you'll have the problem you've described. This problem seems to be amplified when using L/W board. I've adjusted this problem by installing one field screw every other stud on wall boards, then remove them after the job is 2 coated or the glue has had time to set up/harden. You end up having to 4 coat the screws, but a small extra step like that is much easier than repairing work in a lived in house.


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## gazman (Apr 29, 2011)

Glue is part of our code over here. You are not supposed to screw within 8 inches of the glue.


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