Weird Drywall Patch Failure

I have a bunch of drywall tape that is just releasing and peeling. I performed these repairs 9 yrs ago and they have been fine until recently. These were all strip repairs where I removed drywall to route new wiring. These are not tension or compression failures. Every piece of paper tape is visible with a crack on each edge. There is no evidence of any water damage. I can repeat the repairs, but am baffled as to why this would take so long to occur.

 

So is there drywall behind the paper, or a gap? Was the gap completely prefilled, or could air from the stud bays come into contact with the back of the paper?

I guess I'm wondering if its humidity from either cold air contacting the warm paper in winter or hot humid air contacting the cooler A/C wall in summer that eventually got to the paper. Or if that's not the case, it's just expansion and contraction eventually getting the best of it, assuming the drywall on either side is not really connected anymore if you cut a slot out of the drywall... if so, you basically created an expansion joint.... 9 seasons of expansion and contraction, getting progressively worse every year until it got to the point where you noticed it had failed.

Paper tape that is wiped down "too tight" will tend to peel away clean if there isn't enough "goody" on the back of the paper to allow it to stick. Won't take much increased humidity to make it peel.

 

I am having the same problem in my garage. I suspect it is as X explained, too little mud behind the tape (too much squeezed out initially) as well as never laying on a cover coat of mud. Some day I will have to remove the little that is still in place, scrape the joints and then re-tape the entire ceiling. I think I will wait until I add drywall to the walls first, though. Probably will have to wait until my second lifetime.

 

Too little mud or mud thinned too much are common causes of tape lifting later on. High humidity [like in a garage or bath rm] can also be an issue.

 

I've also seen this happen when there was a lot of sanding dust on the sheetrock before it was taped.

 

The sanding dust might be a problem. When making repairs, I always take a power sander to knock off the adjacent texture, so I don't get knife chatter. I may have been less than diligent in vacuuming or wiping it down. I doubt with our dry climate that humidity is an issue. Also, this BR has a window AC, but it is run only when we have a guest which is pretty seldom. I doubt that I squeezed out too much mud on the bedding coat, since the problem hasn't shown up on any other of my considerable drywall work in this house. BTW, one inside and one outside wall is involved. On the outside wall, the tape is lifting and curling. On the inside it is just cracks that outline every piece of tape. This would have all been one bucket of premixed mud and roll of tape in 2007. Any one ever hear of a bad batch?

 

A bad batch is possible but not likely, it would be more likely that a bucket of mud went bad either from extreme heat or below freezing temps ..... not that I think that applies to your situation.

 

Just one more question. I use premixed mud for convenience, but it is usually thinner than I prefer so I add a little 45 minute dry mix to stiffen it. Is this ok?

 

Straight out of the bucket it's too thin ??

I've added setting compound to ready mix compound when it's too thin, it does work BUT you can not return any of the amended j/c back into the bucket as the setting compound will contaminate the rest.

 

Setting compound cures whereas joint compound dries, hence Mark's comment about not being able to re-use any joint compound which has had setting compound added to it.

 

Agreed. I never reuse any mixed compound. Thanks guys.

 

If mud out of the bucket is too thin do you still have a shoulder and elbow left?
Is there something you are not telling us. Maybe your mud was so stiff that it did not moisten the tape and embed it. Does seem strange though that it took this long to show.

 

Good point, tape has to be wet in order to stick good. I agree, it's odd.

 

I always moisten the tape. I am not a pro, but have done a few thousand feet of joints and never encountered this before. I shall be more careful in the future of dust on the surface. Of all the things mentioned here, that sounds like the best suspect----but it still took 9 yrs. Just when we think we have seen it all, something comes out of left field.