all the advise i can get would be greatly appreciated. finishing wall 20" in height 5/8", with existing drywall already previously hung, finished and painted. rookie here so any advise would be great.

 

How long is the wall? are you hanging the entire length?
Generally it's not a big deal to tape and finish up against finished drywall. Butt joints typically need to be floated out further. It's a good idea to scuff sand the paint, especially if the paint has any sheen.

 

Thanks,
Sheen? Does that mean shine? What is score sanding I've heard different Mudding steps from sanding every coat of mud to just the sanding last. Or using mud knife only after each coat For light scrape for any clunks and sand last. Very confused and lost. Any other tips???

 

Sheen means the shine on the paint as in enamels. A scuff sand is just a quick light sanding to rough up the surface a little to promote better adhesion.

Whether or not to sand between coats of j/c depends a lot on how well you applied it. I only sand the top coat but I will scrape off any ridges left by the drywall knife. That's fine if you apply the mud fairly even. If you have dips and humps - you're probably better off sanding between coats of j/c.

Thinning the j/c slightly [but mixing it well] helps the mud to be easier to apply neatly. Try to use up what you put in your pan or hawk. If you put mud back in the bucket it will often introduce trash [mainly dry specs of j/c] back into the bucket

 

Thanks marksr. Is a 6" 8" & 10" knife ok. How high from center should final coat be? Is the first coator second coat the thicker one. I know the third or last should be the thinnest. And screwing in panels 2 screws per stud ok? Also should finished sheet above it get a screw at the bottom since it was cut?
Thanks

 

I like to use an offset 3" knife for the tape coat but a 6" will also work. I use the 3", then a 6" and finish with a 10" A 6"-8" wide coat of mud is usually sufficient for the factory beveled edge joints. Butt joints generally need to be at least twice as wide.

I normally thin the entire bucket of mud when I first open it. I use a paint paddle and drill. If it isn't spreading good, I'll thin it a little more in the mud pan. Just be careful not to thin too much as you can always add more water but you can't take any out. While you want enough j/c over the tape to make it disappear, you don't want it thicker than needed. Ideally, a factory edge joint will be perfectly level all the way across. Since butt joints can't be made perfectly level, you float them out far enough to give the illusion of being level.

Generally you screw the perimeter of the drywall about 8" or so along with a couple of screws in the middle of each stud. Since your drywall is only 20" wide - you probably don't need to secure the middle. The old drywall might benefit from screws being added, it really depends on how solid it feels.

I probably should add that the paper drywall tape has a better track record than the self adhesive mesh tape.

 

Cool thanks. Any tips on corners. Are the metal ones faced in paper good. There's existing metal ones above. Not paperfaced. Tought abought the plastic ones but the guy at menards gave me these. So put one in last nite and it was more tricky than I tought. I have a good idea on mudding seams but these corners I'm still a little unsure about. And boy was it time consuming. Trying to get it all perfect. I have both knifes to use. The straight 6" or corner one for inside and out. I stuck with the angled one to get a smooth edge cause the knife gave it a sharp looking edge. But boy was it hard cause I kept getting linesfrom top to bottom. The straight knife after doing both sides I figured it would look to sharp. Or am I wrong. And does the actual edge not get as much mud with straight knife Also can I stop and start second coat considering the rest that will be connected to it has not been hung yet. I really want to practice and make sure I can get a decent outcome before I hang and start the rest
thanks!

 

I've only used the metal corner bead. I'm a painter not a drywall finisher..... but I always get stuck making repairs and have done all the drywall hanging/finishing in my house.

Unless there is a need for specialized corner bead, I'd stick with the traditional metal bead.
I can't see what those are

I always use a straight knife but the corner knife can be helpful for inside corners, you wouldn't use it on the outside corner where the bead is. When mudding over the corner bead, hold one end of the knife fairly tight over the bead and less pressure on the side over the drywall. Each coat goes out a little further until it's all nice and smooth.