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Discussion Starter · #1 ·
Hi guys!

I just signed up after lurking these forums for a while, and they have been a huge help for me as a homeowner currently remodeling half of my house.

The problem:
I have a wooden house (with wood studs all over), and after mounting drywall I have quite a few joints were the plates aren't perfectly level, as when I put a 12" knife across it rocks slightly. I got a bit discouraged by that, and realized this will be a lot more tricky than I anticipated.
Anyway I'm working to get the hang off floating butt joints and the misaligned factory joints out so they become invisible to the eye, but I have a hard time getting the result I want. Before and after sanding I still find the knife rocking across the joint, only to a less extent than before, and conclude I have failed at floating them out properly (even though I can't feel the joint/bump with my hand).

This might be a stupid question but I wonder if the goal really is to end up with a joint where the knife wont rock? I mean, the bump will be there no matter what one does, its just a matter of visually hiding it to the eye?
 

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Goal is to make butts smooth + flat, not flush.

From beginning, don't slam butt joints together, it pushes them down a bit. Also, slice the factory edges, as they slightly lift

When coating butts, go wide,. Double your trowel size with each coat. Feather edges first, then flatten middle barely covering tape. Sand, repeat, sand, repeat. Don't need a big glob of filler on butts, tape is only paper thin...fill sides of tape.

A hump trowel on first pass is a DIYers best friend. Bend an old trowel over stove.
 

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Discussion Starter · #3 ·
Thanks @Tonydif
I think my mistake then is that I've been trying to make the butt joint a long/wide "arc". What I understand from the videos I've seen and your reply I should be making a flat section just barely covering the tape in the middle, and go another trowel width out on each side of the flat area and feather those edges.

Not sure what you mean by slicing the factory edges though?
 

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Correct, no heavy arc, just a gradual flat fill.


The edges of drywall (sheetrock) have the slightest delaminating of the paper. Causes a fine lift and sometimes gets loose. Take a sharp knife and cut that paper off. Some call it " V-ing " the butt. If take your finger and swipe that edge of sheetrock, you'll feel the paper face move sometimes....this loose paper always shows itself after tape, fill and paint.
 

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Discussion Starter · #5 ·
Oh yes, I've been doing that luckily. I've also prefilled after V-ing the butts prior to taping so hopefully they wont crack!
 

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Use fibafuse on butt joints instead of paper or mesh tape
fibafuse is super flat and actually embeds or fuses with the mud giving you the flatest taped joint possible
 

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youll need to go a lot wider than 2 knives if they really bad. i have tamed some you could put fingers under the blade. use 45min. and just keep coating and checking. never be flat but you make the illusion that it is. sometimes for noobs its easier to run both sides then next coat fill in middle. it allows you to see how thick your coat really is.

your "arch" thinking is correct but the peak needs to stay thin. it is actually a very gradual arch your trying to achieve.

this is a good short example of how it should be run. he uses 3 times the knife strokes that he should need though. and i dont sand between coats if regular mud. fast set i scrape lap marks before dry.
how to run a but joint - Bing video

man i had to weed threw many incorrect videos to find this one. lol hope it helps ya
 
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