Hi folks,
First a little background. I have been doing general remodeling for a number of years and would consider myself and intermedieate level drywaller but by no means an expert.
So I put up a new ceiling for a client and have two issues.
1. On a small section of a bevel joint I have a hairline crack about 1 1/2′ long.
2. On the butt edge I have a “bubble” line for about 4 or 5 feet. This was not there before I primed and painted.
What I’ve used. 1/2 inch drywall, bevel seems perpincular to ceiling joists, mesh tape, ( I usually use paper but the Holmes on Homes guy said he liked mesh so I decided to give it a whirl), Lightweight all purpose joint compound. 4 progressive coats of mud.
This is a single story house and there has been no work in the attic.
In my exerience with drywall I know that if the drywall has gaps at the seams the tape will bubble up but these seams are nice and tight. Also, I put a light across the joint before I primed and it looked sweet.
I am sort of a perfectionist and it is driving me crazy having these two issues.
Any help would be appreciated.
Regards,
Howard
Replies
I only use Durabond to imbed mesh. Dries harder and adhesive content higher. Same goes with paper, tho I don't think that is as necessary.
How you got a bubble with mesh I do not know.
Could the board have been boogered up on the butt end? And why more than 4'? Did you stagger the sheets?
nope didn't stagger the joints. It could be longer than 4' I am going off of recall.
Howard
Durabond!
Best stuff in the business! Why on earth it is almost unknown in the Bay Area is a mystery to me. Out here the often use this crap called "Fix-all"
Vallejo Area Durabond source
Where in the northbay is durabond available?
Latex paint can "reactivate"
Latex paint can "reactivate" a bad adhesion of the mud to board.
And the board surface paper may look good, but if the gypsum is crumbled or missing a bubble looking area will probably show up, again with the moisture of the paint softening the compound.
Butt joints really should be staggered on walls and ceilings. More stress and movement on a continuous joint across several boards.
I only bed tape using durabond or general purpose, never lightweight. Every article I've ever read about bedding recommends green top mud or DB. Even so, you can get bubbles if you starve the tape by either spreading on too thin a layer, or squeezing too much out after bedding.
The debate of mesh vs paper will wage on as long as both are on the shelves. If I use mesh - which is very rare - I bed it in setting cmpnd, and I believe the mesh tape instructions recommends this, though I I'm not sure.
If you look a new roll of mesh that still has the label it says that ONLY setting compound should be used. The consistency of your mud may also contribute to the problem. Keep it stiff.
Now you have learned why you HAVE to stagger gypboard which I assume is attached with screws in the proper schedule. Closer on the perimeter than the field.
Being picky I'm surprised you used 1/2" on a ceiling--it should be 5/8" especially if textured as it introduces enough moisture that is absorbed by the gypboard and it sags (especially if attached to joists 24" OC) but makes everything "iffy" with 1/2". You probably didn't use mesh on a butt joint but ............
Thanks for the info folks.
I will definitely stagger next time and I think I will stick to paper.
With that said, What is the preffered compound for paper tape as opposed to mesh?. If settingk type, is that only for bedding or for the remaining feathering steps as well?
Also, how do i go about repairing the hairline crack?
Honestly, I didn't know to go with 5/8". The joists are 16" o.c. and I "over scheduled" the screws and this is a smooth ceiling.
Looks like I need to study up a bit on the technical aspects of drywalling. Again I appreciate the input.
Regards,
Howard
My preferred setting compound is Durabond-90 or 45 depending on the amount of job I've got. Regular joint compound in a bucket is also fine. You take your chances on the liteweights and bucket toppings.
Second and third coats I usually use bucket litewt or if wanting to speed up the finish-Litewt 45 or 20.which I mix.
How to repair the crack? I would need to see it. It cracked for some reason. Movement-I'd rescrew probably. Tape lifting-I'd cut out the bad tape (once exposed edge, should pull off easily. Real pisser-but you have to do it right this time-no wanting to see it happen again.
Best of luck.
Experience is a good teacher. But USG has a handbook of best practice/industry standards. You might be able to pull off some helpful information out of it. May be available online. It's been a long time but while much of it deals with hanging-I think some mention of finishing.
Taunton offers a book by Myron Ferguson on hanging and finishing. I've heard him at trade shows and he's good and easy to understand.
Used to always be 3/4" on
Used to always be 3/4" on cielings, but I'm seeing more 1/2" lately. but we are using cieling board (1/2") that is much stiffer than regular 1/2". So, I wouldn't worry about your your 1/2" on 16" centers, especialy with a smooth surface as opposed to a texture.
Next time, you should stagger your joints, not much you can do about that now except for pulling it down. To try to fix it, pull your tape off (entire seam), then cut a space between sheets with your utility knife, prefill the gap with durabond, let that dry then set your tape with durabond. You can finish from there with the lightwieght compound.
Personally, I like the mesh, but not for butt joints because its too easy to sand too thin, exposing the mesh
There are lots of ways to arrive at a decent and longlasting drywall job, but my favorite rules to help prevent problems are:
-Glue it in addition to screws
-For prefilling, ALWAYS use one of the setting type compounds (I prefer to prefill any gap 1/8" or larger prior to taping)
-set your tape with setting type compound or regular mud (green top)
For subsequent coats:
-use the lightwieght (sands easy, but not very strong and dings easily, sometimes dries leaving pock marks)
OR
-topping compound, a little harder to sand, but seems "creamier" and easier to pread nicely.
-use
You didn't stagger your joints? Drywall 101 ... ALWAYS stagger the joints ... just like plywood.
One trick I learned from the guy that did my house was to, in as much as possible, never let your butt joints end up on framing members. Best to let them 'float' and back them w/ e.g. a 3" scrap of plywood. This is good because: 1) you don't have to measure and fuss w/ getting a 4ft edge to be dead center 2) fasteners near the edge often break the drywall which compromises the structure of the joint at that point and 3) the floating joint is actually structurally superior. Movement of framing won't affect the joint and the joint is stronger because you don't have to put the fasteners so close to the edge.
This makes it a piece of cake to layout a sheet w/out having to worry about having the joint line up.
Tape and compund
I could frame all day for all the problems that one hour of taping drywal can cause!
I used to have problems with paper tape, eg bubbles, etc.
I took a hint from the pros who run their paper through a bango; a device that coats the paper with a thin layer of compound on both sides.
You can do this with a bucket, but very messy. I simply pre-cut my tape and drop it in a bucket of water. I then wring it out and apply it to the wet compound. Squeeze out the excess, smooth and voila; no more bubbles.
You can use setting-type durabond, or green-top compound as a first coat with paper tape. The setting-type compund is exothermic, meaning that it generates it's own heat. So, it dries faster. I always make too much and have it dry in the bucket!
GP compound is fine too, easy to work with. Takes much longer to dry. Since it dries by the evaporation of water only, it tends to shrink.
If you want the best of both worlds, mix up a batch of Durabond, and then add some gp compound for workability and sandability.
Maybe I will be called "Old-School", but in the 80's you couldn't really sand Durabond, hence the hybrid mix.
In my area of New York state, Durabond is called "Setting Type" compound.
What I usually use is screws 8" on butt ends, 10"-12" in the center, mesh on all except the corners, 20 min sheetrock brand drymix, and if I am on the job a few days I'll use the green lid in the corners. I havent used paper tape on beveled joints or butt ends in years though I have fixed many, many, many bad tape joints (mostly from DIY homeowners) when paper tape was used. I found its usually poor bedding when the paper tape bubbles.
As for your mesh tape bubbling down on your butted end...... If there was a gap, and you filled the gap with compound then applied the tape, gravity would make the compound push the tape down as it would sag out of the gap. Check to see if there is mud or air (empty space) behind the bubble. Paper tape is easy to removed and replace. Mesh tape, not so much. Is easier to run your knife along the crack or bubble and reapply new mesh. They also make 6" tape. I use 6" tape when repairing a DIY'ers attempt to do drywall.
For your crack issue, Is it a straight crack or does it vary? There are many reasons for compound to crack. In this case, without seeing it, I would rule out movement and lean more toward heavy compound application (too thick of a coat will crack) or again a gap. But its tough to determine without looking... Feel free to post pics.
Good luck!
Bubbling....
It could also be that the bubbling was due to minor contraction/expansion of the joists due to seasonal or a situational moisture changes. Sometimes central heat speeds these changes up and sometimes moisture gets trapped in the space above, etc.
Also, because the butts were aligned, any sag due to the added weight of the rock on the joists would be amped up causing the edges to lift..
I always at least bevel my butt ends and I try to leave a gap for dimensional changes. The best technique is to float your butt joint between joists and use one of several methods to slightly concave the joint so that to disappears.
Myron Ferguson's drywall book (Taunton) mentions this. It's a really excellent book, even for old dogs....
Bubbles in drywall
... Perfectionism may be the problem. I was a perfectionist when I first started taping, and pressed too hard, trying to get totally smooth coats. Which pressed out too much mud, allowing air in, creating bubbles on the next coat. I have found the opposite problem from you: If I don't have a gap between sheets, I more often get bubbling. These days, I want about one -eighth gap and set paper tape in mayo consistency durabond. The thinnish consistency makes it easier for me to load mud into the gap (which seems to hold better in the long term, sort of like keying plaster when using lath), and forces me to press more lightly when setting tape, aka I go a lot faster than I did when I was new to taping.
Calvin mentioned the USG handbook, which has a LOT of information and is available here:
http://www.usg.com/resource-center/gypsum-construction-handbook.html
I've only used it a little, but I've had good luck with the self-stick perforated paper tape.
Like I said, I only used it a little. And used setting mud on top, similar to mesh.