We've just completed our first drywall project and the outcome wasn't so great in places. There are a couple spots in particular that have 1/2-1/4" gaps.
I was wondering, is there a nifty way to close these gaps or do we have to pull the panel down and try again if it is too bad? I don't think that just slathering mud in it will work.
Setting-type compound (the bagged kind you mix vs. the drying-type you buy premixed in a bucket) will easily fill a 1/2" gap without cracking. Make sure you load up the gap well before applying your tape, then finish it as you would any other joint.
Sadly I have a lot of experience filling this type of gap from my own basement project a few years ago...
Use 90 joint compound that you have to mix and flush fill below level then tape and finish coat with lighter mud.
I'd probably cut a small sliver of drywall and put it in the crack. Have to cut because it would be hard to snap a piece that small.
I had a gap at the top of the drywall of about 1 inch on one end tapering to 1/2 inch at the other end of a length of 36 inches. I took a 2.5 inch wide piece of drywall doubled scored in the middle of the backing for 1/2 inch for the whole 36 inch length. I then snapped the 1 inch ends and peeled off the drywall from the front paper. This left me with a 2.5 inch wide 36 inch length of front drywall paper with a 1/5 inch piece of drywall running down the center. I then used this like drywall patch paper and joint compound to close the gap. It wasn't perfect but it worked.
I would probably take the panel down and try again.
Even if you used fiberglass mesh tape when you tape the joints, it'll be hard to finish the surface, and you're probably going to experience premature cracking, etc.
You could try filling in the gap with one of several materials:
But I'm not sure how the mud would dry over material like that. I'd imagine that it'll still be more prone to cracks than a tight gap. If you are going to try to fill the gap, a harder material would probably work better than a softer material like foam, simply because it would provide more support against bumps and scrapes.
I've filled large gaps in new installation drywall as my house is old, not square, and has some very unusual shapes. They've stood up 20 years without issue. If there is backing behind the drywall, such as a stud, just start filling it in. Let it dry between coats. If you have a situation where there is no backing such as between wall studs, start by tucking so that the compound forms a hook over the back of the drywall. It is the same premise that was used to attach plaster to lath. I push in some fiberglass mesh on a second or third filling, but before flushing out the seam and applying the finish tape. It will work fine. Don't worry about it.
You should use a mud with a hardener and fiberglass tape. Bucket mud doesn't adhere with fiberglass very well and will crack eventually. Fill the gap with mixed mud, fiberglass tape. After its dry finish with bucket mud.
Synko Concrete Fill Wall and Ceiling Compound, 15 kg Bag
Lath and plaster houses are effectively what you are describing. Two pieces of lath (wood) that span across the studs or joists with a 1" gap between them. These gaps were plastered overtop. The plaster would form a key structure behind the lath which gives it strength to hold onto the ceiling lath or the wall. Sometimes horse hair would be mixed into the plaster to give it extra strength.
You can use concrete fill in much the same way. Concrete fill chemically dries, has low shrink, includes fiberglass fibers to give it extra strength. If you want a perfectly flat seam, you under fill and finish off in a traditional drywall sense with tape and taping compound feathered out to the edges.
