# Hairline crack - ceiling meets wall.



## cjaustin81 (Sep 4, 2014)

I'm prepping to paint my family room and I've been fixing nail pops. I noticed in the corners (where the wall and ceiling meet) hairline cracks, near some of the nail pops. 

Should I caulk these w latex caulk? Or just run some joint compound over them? If I were to caulk should I do it after I prime the walls/ceiling?

The cracks are small and near some of the nail pops. I'm not sure if these were originally caulked.



























In this pic it almost looks like the installers may have originally used caulk, it's hard to tell.


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## Jmayspaint (May 4, 2013)

Caulking them will work to an extent. The "correct" fix would be to re tape and mud. Caulking them is obviously way easier and if that suits you, it can hold up pretty well. Use a good elastomeric caulk and try to force it back into the cracks. I like to caulk them twice letting the caulk dry in between.


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## cjaustin81 (Sep 4, 2014)

It seems like the tape is still solid since the cracks don't seem to penetrate the paper (I could be wrong but they're very small and near the nail pops) but I did notice I can see the edge of the tape in some areas (ceiling side of the ceiling/wall corner) ever so slightly to the touch (as if it needs more mud and to be feathered out).

My big question is whether I can just get away w caulk. It doesn't appear too bad and would be from settling I would assume. 

Do I just caulk the areas that show hairline cracks? Or do I have to do the entire edge of a wall at a time? Do I do this before or after I prime?

I noticed a corner where two walls and the ceiling meet have a slight crack too. I imagine I want a paintable latex caulk w some silicone in it (for flex).


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## stick\shift (Mar 23, 2015)

I agree re-mud and tape is the way to go to really fix this. Kinda looks like the screws in the ceiling got too close to the walls - generally, if the ceiling is rocked first, you don't put screws closer than about a foot from the walls and let the wall rock support the edge of the ceiling rock. The two can then move together a bit if needed without having cracks appear.


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## cjaustin81 (Sep 4, 2014)

stick\shift said:


> I agree re-mud and tape is the way to go to really fix this. Kinda looks like the screws in the ceiling got too close to the walls - generally, if the ceiling is rocked first, you don't put screws closer than about a foot from the walls and let the wall rock support the edge of the ceiling rock.  The two can then move together a bit if needed without having cracks appear.


I'm surprised for just these tiny hairline cracks it's being recommended to retape/mud. 

If I were to retape, do you have to remove all the old tape or do u just cut the seam of the tape on now and retape over that?

The original installers nailed the drywall 1-2" from the wall, which are the nail pops I've been fixing. I've been using a nail set to bang them in and putting a screw 4" away from it (5-6" away from the wall).

I'll get some more pics tonight but I wonder why I can see the 'edge' of the corner paper (ceiling side). It seems like the paper is still secured. 

I see a lot of articles online saying to caulk, I guess the question also is how big do the cracks need to be to require retaping vs caulking?


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## cjaustin81 (Sep 4, 2014)

The hairline cracks seem to be in areas where the nail pops occurred. As seen in this picture the edge looks good except around the popped area.


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## cjaustin81 (Sep 4, 2014)

Today I went to a local BM store and showed one of the guys my pics of the hairline cracks. He said to just use siliconized Acrylic caulk (shown below). 

I was able to take some better pictures of these hairline cracks. You don't notice them unless you're on a ladder looking under heavy light. 

What do these look like there from? Should I be putting tape over these nail pops? (I've been spackling, followed by mud)























































Here's where you can see the edge of the tape. I'm not sure if this was from fixing nail pops.









I can add mud and feather it out like this.









The slightest crack just at the tip of where the corners meet.









Does it look like these seams were originally caulked?


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## cundiff111 (Mar 19, 2015)

I would scrape as much of the old 
Tape & bed off without going to deep! Then retake & bed that 
area, but 1st. I'd check the ceiling for a leak because in one of the pictures it looks like that may be your problem where it is pulling 
apart, if that problem , you don't want have. to redo if it lacks again
I've heard it said, measure twice cut 
once, the same applies here. Good luck.


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## Nestor_Kelebay (Jun 17, 2008)

On my PLASTER walls and ceilings I often have problems with cracks in the plaster as a result of the building moving due to frost heave in winter. I use a procedure called "sponge caulking" where you basically apply an acrylic (or any water based) caulk to the crack and fill the crack with your finger. Then, using a damp sponge and wiping ACROSS the crack, remove the excess acrylic caulk from the surface of the plaster. The idea here is that as long as you're wiping across the crack, the sponge won't penetrate into the crack hardly at all, so that you can clean up all the caulk except what's in the crack. Don't do more than a few inches at a time when sponge caulking because the caulk dries up quickly when it's thin, and it then can become more difficult to remove. (If push comes to shove with acrylic caulk, you can always remove it with acetone, but that will also remove the paint on the wall. If you're prepared to repaint that small area, then acetone will work for you.)


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## cjaustin81 (Sep 4, 2014)

cundiff111 said:


> I would scrape as much of the old
> Tape & bed off without going to deep! Then retake & bed that
> area, but 1st. I'd check the ceiling for a leak because in one of the pictures it looks like that may be your problem where it is pulling
> apart, if that problem , you don't want have. to redo if it lacks again
> ...


Thanks for the reply. I can understand your concern about a leak but I haven't seen any leaks (water marks) anywhere.

What I do know is the house had very high humidity last summer (up to 70%) since I wasn't running the AC followed by a very cold/dry winter. The other thing to note is those areas had the edge of the nail head UNDER the tape.. So when I pounded the nail pop back into the drywall the drywall may have moved ever so slightly exposing some tape lines.

I'm fearful of removing good tape of I can just caulk the edges and feather in the couple areas where the tape line shows.


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## cjaustin81 (Sep 4, 2014)

Nestor_Kelebay said:


> On my PLASTER walls and ceilings I often have problems with cracks in the plaster as a result of the building moving due to frost heave in winter. I use a procedure called "sponge caulking" where you basically apply an acrylic (or any water based) caulk to the crack and fill the crack with your finger. Then, using a damp sponge and wiping ACROSS the crack, remove the excess acrylic caulk from the surface of the plaster. The idea here is that as long as you're wiping across the crack, the sponge won't penetrate into the crack hardly at all, so that you can clean up all the caulk except what's in the crack. Don't do more than a few inches at a time when sponge caulking because the caulk dries up quickly when it's thin, and it then can become more difficult to remove. (If push comes to shove with acrylic caulk, you can always remove it with acetone, but that will also remove the paint on the wall. If you're prepared to repaint that small area, then acetone will work for you.)


Thanks again for your always helpful reply Nestor. The caulk I bought is siliconized and should be water based (I think). It should have a slight flex w it along w a 50 yr guarantee. I have to paint everything, which is why I'm doing all this prep (to prime/paint). I feel like the tape is still in decent condition and this is from settling and moisture.

The trick is going to be working a foot at a time like you indicated since this is a fairly large room and I have a lot to apply. I'm hoping it doesn't turn out too 'rounded' so I can get a nice paint line.

I just got done silicone caulking a bathroom so the acrylic should be far easier. I'm going to get a handheld sponge and try your suggestion, thanks!


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## 123pugsy (Oct 6, 2012)

Is the ceiling drywall screwed to trusses?
I read that if the screws are too close to the walls, when the trusses lift, and they will lift no matter what, you'll get cracks.

I will be keeping screws well in from my walls on my second floor ceiling.


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## cjaustin81 (Sep 4, 2014)

123pugsy said:


> Is the ceiling drywall screwed to trusses?
> I read that if the screws are too close to the walls, when the trusses lift, and they will lift no matter what, you'll get cracks.
> 
> I will be keeping screws well in from my walls on my second floor ceiling.


It's nailed to the floor joists. This is the 1st floor of a 2-story. When it was installed 20 years ago they nailed 1-2" away from the wall (first screw). This is why I assume to be having issues.

Whenever I fix these nail pops by driving the nail in, I make sure to put the replacement screw about 4" away from the nail.

For new construction you start the screws 11-12" away from the wall, 8" from ceiling height too.


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## Nestor_Kelebay (Jun 17, 2008)

123Pugsy:

That's called "truss uplift", and the way it was explained to me is that it's because the RELATIVE humidity of the air in the attic is higher than the air at the bottom of the insulation between the ceiling joists.

The result is that the top chords of the trusses expand linearly at tiny bit, and that causes the top of the truss to move upward, causing the bottom chord of the truss also to arch upward. The result is a crack forming between the walls and the ceiling in the middle of the top floor of the house.

The fix, according to the guy who wrote this blurb:

http://www.wwta.ab.ca/homeowner/truss-uplift.pdf

is to use clips on the top plate of the wall to hold the ceiling drywall in place at the walls. Then, don't fasten the drywall to the ceiling any closer than 18 inches from the wall, thereby allowing the ceiling drywall near the wall to bend with the movement of the bottom chord of the truss. But, since there won't be any wide open gaps, there won't be any homeowner complaints.

PS: The guy that wrote that blurb about truss uplift obviously doesn't understand wood expansion and contraction. He says "Wood is weird. Wood expands more across it's grain than with it's grain."

What he should have said was "Wood cells are shaped like long thin drinking straws closed off at their ends. When wood absorbs moisture, it's only the cell walls that swell and shrink; that is, get thicker and thinner within limits. The result is the wood swells and shrinks very much more across it's grain because of the very much larger number of cell walls going across the grain than with the grain." Only the relatively few cell wall "ends" contribute to elongation of the wood along it's grain.


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## cjaustin81 (Sep 4, 2014)

I've read that the wood in winter months (low humidity) can get down to 4% moisture content, and up to 16% in summer (high humidity) 
When the wood is originally shipped from the lumbar yards the MC value can be over 20%. 

http://www.paintsource.net/pages/solutions/new construction/wood_shrink.htm

In my case by having high humidity in the summer and not running much if any AC and no dehumidifier caused the wood to expand. Then in our cold winters we have in IL it was reduced greatly and actually became too dry since I haven't installed a humidifier to my HVAC.


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## Nestor_Kelebay (Jun 17, 2008)

Probably the best primer on wood shrinkage is an article entitled "Detailing for Wood Shrinkage" by Dr. Stephen Smulski. Dr. Smulski used to work for the University of Massachusettes at Amhurst in their Building and Construction Technology Department, but he quit to start his own wood failures consulting company called Wood Science Specialists Inc.

Read this short article, and you'll know more about wood shrinkage than 99% of newbie homeowners:

http://www.paintsource.net/pages/solutions/new construction/wood_shrink.htm

It covers in some detail the drywall nail pops you're fighting with now.

The University of Massachusetts Building and Construction Technology department is very much like University for Carpenters. What I find very helpful are the articles available online from their site:

Go to:
http://bct.eco.umass.edu/

Click on the "Publications" Link, and then open "Publications by Title" in a new window. There's lots of stuff in there that I'm not interested in, but at least I know that everything I do read in those articles is going to be reliable information from people who know what they're talking about.

That's such a relief from the shelf stockers I meet in home centers that will think up an answer to my question as a free service, to save me the trouble and bother of having to think up one myself.


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## cjaustin81 (Sep 4, 2014)

Quick question: I want to repair a couple of these hairline cracks (where the wall meets the ceiling). The affected areas a small (3-5" long). 

My question is do I just re-tape the affected sections? Lets say my wall is 20 feet long, and I have 2 cracks that are 4" each.. do I just fix those 2 areas? (versus pulling the 20 feet of tape completely off)

Another question is when I re-tape the 4" seam (for example) should I "overlap" the new tape over the edges of the old tape or do you try to get the new tape inside the edges of the old tape?

EDIT: I just read in this family handyman book NOT to overlap the new tape with the old. Under "BAD DRYWALL JOINT" > 'Be careful not to let the new tape overlap the old tape.'

https://books.google.com/books?id=284ql850bqUC&pg=PA20&lpg=PA20&dq=retape+a+joint+don%27t+overlap+old+tape&source=bl&ots=iED2RzTLN1&sig=vDBurEq9ihc4nfeGNKXsSkZjzdM&hl=en&sa=X&ved=0CCAQ6AEwAGoVChMIxIrQp-_xxgIVDKCACh0KGABx#v=onepage&q=retape%20a%20joint%20don%27t%20overlap%20old%20tape&f=false


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## Jmayspaint (May 4, 2013)

If you're talking about an inside corner (where wall meets ceiling) why not just caulk it with an elastomeric caulk? Whole lot easier and IME holds just as well as re taping if not better. 

The drawback is that caulking that inside corner rounds it out somewhat and can make getting a crisp paint line a little more difficult (assuming different colors on ceiling and walls).


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## cjaustin81 (Sep 4, 2014)

I was thinking if I caulked it would round out the corners and possibly be messy. Plus I would have to caulk the entire perimeter of the room.

With the tape I was hoping to just fix a couple sections and be done w nice crisp corners. The only issue is my lack of experience taping but it doesn't look too hard w a corner mudding tool.


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## cjaustin81 (Sep 4, 2014)

Jmayspaint said:


> If you're talking about an inside corner (where wall meets ceiling) why not just caulk it with an elastomeric caulk? Whole lot easier and IME holds just as well as re taping if not better.
> 
> The drawback is that caulking that inside corner rounds it out somewhat and can make getting a crisp paint line a little more difficult (assuming different colors on ceiling and walls).


If I were to caulk would I need to do the entire perimeter (all 4 wall/ceilings)? Or do you just touch up the areas where it's cracked?

Reason I ask is because it's a big room (family room leading into open kitchen) so if I do have to make it all uniform with caulk it may be a big job but I'm curious what you think.


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## ralphwaldo (Jul 24, 2015)

Might be truss lift, if your house uses them, especially if it's near the center of the house. 

Two possible fixes, if so. 

i) pull the screws nails out near the edges and corners and let the drywall flex. 

ii) put in crown moldings

iii) go up in the attic and put in nailing blocks at the tops of the walls between the trusses. pull the drywall nails out and renail only into the blocks. 

ok, i guess that's three. 

disclaimer, I'm a newbie so check with someone who has a clue. and this thread is too long to read it all. sorry if this is a repeat or whatever, it's free.


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## cjaustin81 (Sep 4, 2014)

This isn't truss uplift since this is the first floor (I have a 2 story home) and there's no attic above this floor.


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