I've encountered the same problem in my own home, although the drywall and ceiling seam cracks only showed up one at a time over the course of a few years, and most of them were present when I moved in. If more than one or two seams popped or nail heads started showing within a month, that seems like it could be a rather large settlement in your foundation, or some other structural problem.
I'd highly recommend getting a foundation specialist to your house sooner rather than later to see if your foundation might need piers to support part of it, or if some other repair is required. In my house, a total of 14 piers were needed along the side and front of the house to support one side and prevent further shifting. There were a few hairline cracks (even small cracks can be a bad sign depending on where and how many they are) in the foundation walls, and the corner of the house had settled over 2" before the problem was found.
The problem could also be in load-bearing structures (walls, I-beams in the basement, etc.), especially if it seems the problems are mostly towards the middle of the house.
The sooner you get this fixed (don't just let it go, even if you have to pay a few thousand), the better. You'll avoid more drywall repair later, and prevent further settlement and degradation of your house's structural integrity.
It looks to me like the cracks are appearing on the board joins.
Some possible causes there are:
- Something went wrong with the drywall tape, or there was no tape used at all? You may want to scratch around and try to find some of the tape? I think i can actually see a bubble seam on the wall, indicating that your tape is pushing out. I would say they didn't pre-fill the join seams when applying tape -- basically a poor taping and preparation job.
![enter image description here](https://i.stack.imgur.com/i9SZJ.jpg)
Other - Less likely Faults:
- The boards may not be secure enough (ie, enough lateral supports, and my be vibrating too much (wind or knocks)
- Structural Fault - do they all follow some sort of pattern? the house may be settling and structurally changing
- Excess Moisture: easy to check (if the area around the crack is damp)
Best Answer
I am not a structural engineer. I'm just a homeowner/remodeler. This kind of diagnosis requires a site by a structural engineer. If you are really concerned about your house, I'd recommend hiring one for an hour or two to visit your home and provide their opinion. Cost is likely $125-$250. Don't get talked into making complicated drawings for lots of money unless they see that there is a problem. You may already have some drawings if you had a permitted remodel.
However, I can talk about what might generically cause issues like this in a house.
There is, as BrownRedHawk suggestions, the benign explanation. These crack could be normal signs of age, material expansion, or harmless settling. If these cracks are primarily at corners or in lines at seams in the drywall, then they may simply be a bad mud job on the drywall. Even how you hang the pieces around doors and windows can significantly affect cracking. If it is the benign problem, you could probably just have a drywaller redo the cracking joints, possible with fiber tape if that wasn't used last time or corner beard, and see if it cracks again. I wouldn't do that until you eliminate the more serious problems.
However, you could have more serious problems.
Some possibilities:
So those are some very general things that could cause this problem. I'd strongly suggest investing in an hour or two of a structural engineer's time if for no other reason than to sleep better at night. If something really foolish has been done structurally, hopefully they would notice and you could correct it before the problem becomes more serious (structure or life threatening). I'd also consider having a drainage guy out to look at your gutter and drainage systems if they aren't in great shape.
Hope that helps.