drywall seams showing through primer

[econguy]

Hello

Several months ago, I drywalled, taped, mudded, and primed a couple of bedrooms. They looked fine until the last few weeks. All of a sudden, I can see a lot of the seams, both tapered and butted, through the primer. The tape itself isn't peeling or blistering, and the drywall itself isn't loose. Rather, it's one of two scenarios...I can either see the crease (and only the crease) along the length of the tape, or the crease has become slightly recessed, forming a very shallow, narrow valley (I think it depends on which way the crease was facing when I first laid the tape). Some - but not all - of these seams have a hairline crack along part of their length.

Can I just add a thin layer of setting-type joint compound for either case? Or do I need to add a layer of tape, and then the 2-3 coats to feather it out? If so, can I add the tape on top of the primer, or do I need to tear out the existing tape and sand the area down?

Thanks for any advice

[TnAndy]

Hard to say without seeing it, but it sounds like maybe things dried a bit in your walls and shrank ( in the case of the slight crack ) and/or the joints weren't finished as well as you thought, and you're seeing it from another angle or in a different light.

I've found very small cracks can often just be filled with another coat or two of paint ( primer is pretty thin stuff to start with ) and be fine....and the quality of the seam from an appearance standpoint, you can apply more joint compound, feather out, and re-sand.

Also, make sure if you add any water to pre-mixed compound or the dry, bagged type, you don't over do the water....that too can cause excessive shrinkage later.

[joe w.]

sounds like to me you may not have applied a full 3 coats. and also the 2nd and 3rd coats you apply need to be fanned out with a 10- 12inch mud knife. but as long as the tape is well bonded, yes you can float it out correctly with no problem. remember, wide knife, thin coats, and dont just mud over the tape. it needs to be about 12 inch float on each side of the tape.

[onerenohome]

Did you give enough time for your coats to dry? Possibly your inner coats started cracking and thus you have seams showing...

[mjpliv]

Having the joint appear a few months after the taping is fairly common.

The first coat/tape bed should always be a cementuous type filler like Durabond because it shrinks very little and cures rather than drying. This allows it to continue curing even under fresh coats of regular, air dry drywall mud. Most people, however, lay the tape in a bed of regular, air dry drywall mud. While the surface appears to be dry before applying second and feather coats, it is still quite wet under the tape. Add a primer and a few coats of paint then it can take some time for the mud to air dry which causes it to shrink, pulling the tape into the void as it does. That would be the slight recess that you see.

The only fix is to skim the ceiling and re-paint.

[BuildWritewell]

If the first coat of mud is a set fast material you will not see the tape and cracking will be minimized in the future.

Add another coat of regular drywall compound unless the tape is loose - Then you will have to remove the loose tape and start at the bottom :(