Repair plaster

[Tiggrawastaken]

How do I fix this in the best way? I'm completely new to building and crafting, and I accidentally broke an edge while installing the board.

 

[tergo]

the skirting board should cover it, otherwise remove the loose part and add a bit of plaster

 

[Claes Sörmland]

Cut away the damaged part with a knife and repair with plaster mortar. Do not smear plaster mortar on the damaged area, it will never turn out well; the crushed and frayed paper must be removed.

 

[mojjen]

Plaster works well. I also use it to fill the gaps before applying paper strips. I usually buy Casco wall filler. WallFiller - Casco

Ps. I would have been more worried about the fact that it looks like you've painted with black ink. Ink has a tendency to seep through both wallpaper and even fabric. It's absolutely a no/no to even store an ink pen in the same room where plastering is done. You need to paint over it with some form of blocking paint.

 

[Tiggrawastaken]

Gypsum adhesive works well. I also usually fill the gaps with it before applying paper strips. I tend to buy Casco wall filler. WallFiller - Casco

Ps. I would be more worried about it looks like you have painted with black ink.
Ink has a tendency to seep through both wallpaper paint and even fabric. It's an absolute no/no to even store a marker pen in the same room that you're plasterboarding. You must paint over it with some form of primer paint.

I had no idea ! I will try to solve it, if the paper strip doesn't completely cover the corner and the damage, should I just add an extra strip on top of the damage then?

 

[Tiggrawastaken]

Cut away the damaged part with a knife and repair it with joint compound. Don't smear joint compound on the damaged area, it will never turn out well. The crushed and frayed paper must be removed.

I will do that! Do I need to apply paper tape over the damage?

 

[Tiggrawastaken]

the baseboard should cover it, otherwise remove the loose parts and use some plaster

No baseboard, so it will be plaster

 

[Claes Sörmland]

I'll do that! Do I need to put paper strips on the damage?

Nope, but a few rounds, sand lightly, putty, sand lightly, putty are usually required to make it look nice.

 

[mojjen]

I had no idea ! I'll try to fix it. If the paper strip doesn't cover the corner and the damage entirely, should I just place an extra strip over the damage?

No, you don't need to cover the damage as Claes writes. But you should place a paper strip in the corner. Just like you do between the boards. Many skip this and just use flexible sealant. If these are newer walls that move, cracks will develop over time. Personally, I don't trust my own ability to spackle in the strips. So, I apply spackle at the base, filling the gaps. Lightly sand. Then I glue the strip with a strong wall adhesive. After that, I spackle in.

Spackling corners - the ultimate guide – Anza Painting Tools

 

[useless]

The corner should still be spackled, right? Then the damage will disappear on its own. You don't need to do anything more than pick away loose pieces.

 

[mojjen]

The corner should still be plastered, right? Then the damage will disappear by itself. You just need to remove any loose pieces.

It's mostly that the hole is so large that drywall filler or possibly coarse filler is preferable. Then I would make sure to fill it up and get it reasonably smooth before it's time for the tape.

 

[useless]

You should still apply a layer of putty before the tape, so that tiny hole will disappear automatically.