hello, I am drywalling my basement, I am putting on my last coat of mud and noticing cracking. I am wandering if I put the final coat on to thick or do I have a bigger problem. I used regular paper tape, and it seems that is where it is occuring. Do I need to sand it back down or can I put a thin coat over top? Any help would greatly be appreciated. Back to top
When mud dries it shrinks and cracks form. Just put another thin layer on.
I used regular paper tape,
Is the mud, only, cracking or can you tell if the tape, itself, is rising (peeling up, separating) from the drywall surface?
If you can be sure only the mud is cracking, then you are caking the mud too thick and, as it dries, it will form irregular cracks, usually in all directions, like in a dried-up mud hole cracking irregularly from drought. This isn't bad. Allow it to dry completely, gouge out or scrape (not sand), somewhat, those areas and skim it again.
If your tape adherence, to the drywall surface, has failed, this means you didn't put enough mud behind the tape for it to adhere properly OR You may have initially put enough mud behind the tape, but you pressed the mud out from under the tape (when skimming, too tight, that first mudding/taping layer). The cracking, due to this lack of mud behind the tape, will likely be a straight lined crack along the edge of the tape (and not the small irregular type cracks as that of a dried-up mud hole). If this is the case, cut out the mud and tape, from the affected areas, and re-mud and tape. If this is the case, you may have mudded and taped improperly, this way, over other areas and your problem may very well show up in those other areas, later.
I hope your problem is the thick mud problem and not the non-adhesion problem.
Sonny
Good post, Sonny! Thanks!
Pop
I drywalled most of my house, and started with paper tape. I had the same kind of problem that Sonny outlined, and could never get it right. I had a pro show me, practiced til I had mud coming out my fingernails and finally gave in to the fact that it was something I wasn't going to learn.
The pro who showed me how to do it disdained the self-stick nylon mesh tape, but I used it anyway. After using it for a few joints I thought I'd died and gone to heaven. No more cracks.
Tanus
No one's asked about the type of mud you're using. Is it the pre-mixed general purpose stuff?
I have nothing but problems using that stuff. Instead I've switched to the setting type compound that comes in a bag and needs to be mixed with water, Durabond 90. It hardens like a rock, has much greater adhesion, and doesnt shrink as much. And its specifically designed as a bedding mud instead of being general purpose.
It's corresponding top coat mud, Easysand, goes on like butter, doesnt shrink as much and really is easier to sand than the readymix stuff. Both are available from the BORG.
I've given up using the ready mixed mud and am much happier for it.
BTW, if you're doing long edge to long edge taping, I find it hard to believe that you can put that much mud in the indent that it will crack when it dries. If you're doing short edge butt joints, then if you're putting it on that thick that it cracks, you really should sand it down, else you'll have a really good bulge in your wall.
dickm
Not really the right group for this, but why not.
I've got a feeling you've fallen into the common trap of thinking there's nothing to taping drywall and anyone can do it. Granted, it isn't exactly rocket science, but there are a few things you need to know.
First, you're hanging new drywall- paper tape is not the thing to use. Get the mesh tape. It allows you to press the mud into the joint.
Second, your first coat needs to be Durabond. Not the premixed mud- It comes in brown bags, and you need to mix it yourself. They have numbers on them that refer to the working times- 90, 120, 210, etc. Get one that gives you enough time to use up what you mix. This stuff chemically cures instead of drying, so it is very hard and does not shrink and crack as it sets. It's tough to sand, so keep it lower than the level of the wall itself. Once that is dry, move to the premixed Plus 3 with the darker blue top (if you're using sheetrock brand stuff) and do your second coat with a 10" knife. Sand it when it dries, and then do a final coat either with the Plus 3 or topping (the premixed stuff with the light blue lid) and a 12" knife.
Use this technique, and it won't crack on you. Otherwise, just keep filling in the cracks until either you or the wall gives up. They'll eventually stop cracking, but it takes a lot more time and work. Where the paper tape has bubbled up, you can either peel up the edge and squeeze in some mud underneith and press it down, or tear it out and start over.
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