Taping the inside, non-tapered corners of plasterboard at the ceiling and adjacent wall.

[OuterSpaceHopper]

Hi folks, I've boarded out one wall with new plasterboard up to the ceiling and to interect with the side wall.

Both the ceiling and sidewall are already finished.
I'm going to skim the plasterboard to finish.

How do I join the new plasterboard to the the finished ceiling and existing sidewall?

I've used tape and jointing compound over the tapered joins in the butted plaster boards.

The edges of the new board are square edge where they meeting the ceiling and existing wall.

Do I need to add a taper to the new board and also to the adjacent finished ceiling and wall so that I can add tape and joint compound?

How do I do this? With a knife? multitool?

Any better idea's? I've found very little on line about what to do when only boarding one wall against a finished ceiling or adjacent wall.

Help!

 

[chappers]

I normally scrim up to the corner just to give the plaster in there a bit more strength and bridge any gaps. Then skim as normal into the corner and caulk the corner in when decorating

 

[OuterSpaceHopper]

Thanks Chappers, it does seem like the corner would need the scrim to strengthen it stop any holes appearing.

What would you do if the other surface of the corner was already skimmed and finished?

wouldn't you end up with a bulge down the corner of the wall or on the ceiling where you skimmed over the scrim?

That is why I was thinking of adding a taper to the finished surface and then filling it back in smooth with the jointing compound.

 

[chappers]

What would you do if the other surface of the corner was already skimmed and finished?

wouldn't you end up with a bulge down the corner of the wall or on the ceiling where you skimmed over the scrim?

No exactly the same, the scrim will just give a bit of reinforcement to the skim, your skim coat will be many times thicker than the scrim so there won't be a bulge.
Not sure what you used on the joints but use this for the corners. Also not sure why you used tapered edge boards if skimming the lot, but if skimming tapered edge boards I would normally just use self adhesive scrim and skim over as normal well nearly normal. I would normally fill the tapers with plaster first before spreading the whole wall, not exactly necessary, but just the way I like to do it.

 

[OuterSpaceHopper]

Thanks again Chappers.

The adjacent wall and ceiling already have been skimmed already(in 1992!) and is in good condition. I have just boarded the chimney wall which has plaster blown and cracked.

Are you saying that I should re skim the adjacent wall and ceiling to cover up the tape?
Do I have to skim the whole surface of the ceiling and adjacent wall to cover the tape? I'm worried if I just skim over the tape in the corner I will end up with a bulge in the surface due to the thicker skim(old skim, plus tape, plus new skim) in the corner.

I have used paper tape and joint compound to cover the tapered joints.
To be honest, I thought that tapered edge, plus tape, plus joint compound was normal prior to a finishing skim of plaster. I thought this produced the strongest joint. I didn't realize that I could just use square edge, tape then skim.

 

[chappers]

No don't scrim both walls/ceiling round the corner. Just scrim the plasterboarded wall tight into the corner to cover any small gaps and then skim into the corners don't skim any of the walls or ceiling that are already finished. make sure you then caulk the corners when decorating. you may get a slight crack down the line but if you do caulking a second time should sort that.
My preference is to mist coat then put a first coat of paint on then caulk and then a final coat of paint. If you caulk first or just after the mist coat then the dry wall is likely to suck the moisture from the caulk and you are more likely to get a crack down the joint as the caulk shrinks.
What you have done is overkill but as you say you will have a stronger joint.