Any substance like drywall mud that dries hard will crack. The only way of which I know to prevent cracks in derwall mudded joints is to make sure the joint itself does not move. If you have done that, makes little difference what compound you use.

Well, IÂm really not sure whether I fixed the underlying cause of the crack (i.e. movement). While there was water damage in that spot and some weaknesses in the framing, I do have other (albeit much smaller) cracks in my wallboard throughout the house. They could be foundation settling, changes in temperature/humidity, building practices that make the house underframed by today's standards etc.. The bottom line is that all the houses in my neighborhood (built by the same builder in the late 50Âs) have this "problem" though most of the owners donÂt see it as a problem and thus give low priority to fixing it.

I have had one too many experts (inspectors, contractors, structural engineers, drainage specialists etc.) come over and give me an opinion (total cost over $1000) and almost every single one of them gave me a different explanation and proposed fix. But most suggested that whatever the reason, it was nothing to worry about and I should just live with it and patch whatever cracks show up every 5 years or so.

One of the structural engineers suggested that there is a way to patch the cracks with some "special" type of mud/putty/caulk? which would make the joint more crack resistant.

I'm not buying the "special" putty concept of that structural engineer. There may be some epoxy product that adds strength to some structural components, but I'm unaware of any special product that is useful in homes for sheetrock issues, and would be able to be hidden by a coat of paint. The underlying issue with sheetrock is that the joints are not very strong in the first place: they're basically cracks with a non-flexible filler compound between. When new cracks appear in a home, the causes are typically normal settling and seasonal variations, and the forces they exert are more powerful than any patching compound. However, I agree that stuff like this is usually mainly cosmetic, and not a sign that your house is falling apart....

There are products that claim to be elastic enough to cover cracks and still allow some movement.

Few of them seem to work well in actual practice.

If the crack is a settling crack you can fill it and it is not very likely to reappear.

The same for wood shrinkage cracks, unless the wood goes through expansion and shrinkage as the humidity changes.

This creates a 'working' crack that continues to move over and over.
You can try caulking compound or some of the 'fix cracks' products, but they seem to fail a lot.

My folks & I used regular bathroom caulk like you use around a sink for repairing cracks from Northridge earthquake back in 1993 I think it was. Anyway still holding. It is pretty flexible & you just rub it into the crack with your finger being sure no open spots let it dry couple of days & paint. The 1 that was about 18 in. long shows slightly, can't find the other 1. Just looked at mom's & can't see her's either. it was just at top of front door going over towards window. She was having company couple days ago so I was checking for spiderwebs, don't usually look up there. If it is not perfectly smooth, wet your finger a little to smooth it. Good Luck! Cheap & works!