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I have a crack in the paint that seems to be getting larger over the years. It doesn't seem to be damp. Could this be something serious or just shoddy installer work?

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Unfortunately many of the homes built in the 80s and 90s have features such as vaulted ceilings and floating walls, and they usually employed engineered truss systems. Those trusses move seasonally due to temperature and moisture changes, and builders hadn't yet worked out how to handle that movement.

In later years devices like isolation channel and expansion joints were installed, which allowed for such movement without drywall damage. Your house (and mine) lack these preventative measures, so we get cracks that come and go.

You have a couple choices, if this in fact the problem you face.

  1. Ignore it.
  2. Rub some paintable caulk into the cracks, then paint. Press firmly and don't leave caulk on the surface to create ridges or seam lines. A lightly damp cloth can help. Such caulk shrinks as it dries, so you may have to hit it twice.
  3. Re-tape those areas with fiberglass mesh. Obviously this requires re-texturing and full-wall painting. Stronger setting-type joint compound (like EasySand 90) for the initial tape coat would be a good idea. Pre-mixed mud is easier to finish with.

All that said, I'm speculating. If you have reason to think you're in a termite area or have larger foundation issues, bring in an expert to look with real eyes.

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    It's common even in homes that don't have trusses. Any house that settles (so, every house) after drywall is taped and mudded is going to have this problem eventually. – TylerH Jan 6 at 14:26
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    Yes, but engineered trusses dramatically enhanced the tendency for lift to occur due to their very rigid structure and connections. The rafters in my 1950s home, by comparison, had nailed connections that had worked quite loose after 60 years. Also, they made it easy for builders to offer dramatic roof and ceiling features, so these issues became more common. – isherwood Jan 6 at 14:29
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    Paintable silicone doesn't suffer the same way that regular painter's caulk does and it allows for joint movement of about 25%. – MonkeyZeus Jan 6 at 16:21
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I had something similar, only horizontal. A hairline crack that slowly got bigger/longer, and was almost a perfect straight line. Turns out, it was the paper drywall tape letting go from the sheetrock. The builder didn't get enough mud behind the tape to make it adhere properly. Granted, it held well enough for about 12 years.

It's hard to tell from you pictures, but it looks like the same thing. The second picture even looks like you can see the tape's outline telegraphing through.

I ended up cutting out the bad tape and replacing it with fiberglass tape, re-mudding it. Took a little artistic approach to get the texturing done right, but it looks pretty darn good. Mine was a small area, about 8 inches long. In your case I'd consider calling a drywall professional.

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    This is a good suggestion in general, but here we can plainly see the deep cracks and tearing that only come from movement. – isherwood Jan 6 at 14:19
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Isherwood goves some good options here. One thing I've done that seems to have solved a similar issue over the last couple years was to take a utility knife and open the crack into a V-shaped 'trench'. Someone had previously attempted to use mesh tape which I removed entirely. Then I layered in joint compound over a few days to fill the crack level with the wall. Then I put a little spray on texture and painted to match the wall. I haven't seen the crack since.

It's important to not fill in crack all at once. The joint compound will take forever to dry and it will shrink. Fill in a little and let it dry completely before adding more. I would also advise against overfilling and sanding. You don't want to spread all that dust in your house. Try to get it basically smooth with a putty knife. Light sanding is all that you should need.

Update:

I thought a little more about why making the crack wider is important. I had never really considered why, I just got the idea somewhere and it works (every time, in my experience.) So here's a hypothesis about why it helps which essentially comes down to geometry. To simplify the model, assume we have two pairs of nails on a wall separated by a crack which we have connected with an elastic band. Like so:

enter image description here

It doesn't really matter what the units are here but let's say millimeters. One band is 1mm long the other is 4mm. They both have neutral tension in this position i.e. they are not stretched. These bands are flexible to a point. They can be stretched to double their neutral length but beyond that, they will snap.

Now imagine the right side of the crack shifts down 2mm. Now things look like this:

enter image description here

The longer band has been stretched 13% of it's capacity. The short one is stretched to 120% of its capacity. This is beyond its limit and is expected to fail. Obviously joint compound is not an elastic band but it's a flexible bonding agent which will fail when it's stretched significantly.

So when you fill a tight crack with something flexible, it's like the second (closer) pair of nails. When you open the gap wider before filling, the situation is more like the first pair. It's generally not feasible to control the vertical movement but you can reduce the stress by widening the gap. It's going to be hard to finish a wide gap filled with caulk so that's why joint compound is used here.

Whether you tape this is up to you. I know it's recommended and I see a lot of people claiming you will definitely get cracks if you don't use it between drywall sheets. I think that might be a slightly different situation and I've found mesh tape in a few failed crack repairs in my home. I used this method with no tape to good results. My walls are mostly plaster over lath-board, though so that might make a difference here.

Here's a picture of the repair I made a couple years (or more) on. You can see where I made the repair here because I didn't get the texture quite right (it's an art, for sure) but no cracking to be found. I wish I had a pre-picture but I did find a hairline crack in a different spot that wasn't repaired this way. Perhaps when I get that one, I'll document it for posterity.

enter image description here

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    I'm surprised a repair with no tape is holding. That sounds like a sure fail. How long has it been? – isherwood Jan 7 at 20:27
  • @isherwood 2 years at least. I'm fairly certain the cause is seasonal movement. The prior repair with tape didn't work at all. The tape just popped the paint into quarter-sized chips as the wall moved and I think made things worse. I'm not really sure how tape helps here, it's never going to prevent the movement. What you need is something that will accommodate the movement. I think I got this idea from Ask This Old House or something. – JimmyJames Jan 7 at 20:33
  • No, it won't prevent movement, but there's a reason joints are routinely taped. :) Even without structural movement I'd expect a hairline crack after a while. – isherwood Jan 7 at 20:35
  • @isherwood It's really crucial to open up the crack which might seem unintuitive. My prior home had a lot of really bad cracks like this that opened up every year and I had a lot of opportunities to try things including mesh tape and rubberized sprays. This has been the most reliable fix I've found. Next I get to try to solve for improperly installed crown moldings : | – JimmyJames Jan 7 at 20:45
  • @isherwood Yes, good advice but I don't want to cut new ones. They are installed with butt-joints along a long ceiling so they open up every winter and the joints are all cruded up where someone tried to caulk the gap. I'll be posting a question one day. I also think I have some idea why opening the gap helps with the wall cracks. I'll update the answer with the reasoning. – JimmyJames Jan 7 at 21:50

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