Crack in sloped ceiling

[Many]

I have a tricky crack to repair because there’s nothing behind it - any advice on how to fix this would be appreciated.

 

[robinbanks]

Use a Stanley knife to gouge out the sides of the crack on an angle, then fill it with toupret, easy fill or similar filler, then (when dry) sand and paint

 

[Many]

That’s how I usually fix a crack, but when I attempted to make the crack wider I found that there is nothing behind it so any filler will just fall out.

 

[robinbanks]

Show new pictures of the wider crack. Might have to get serious and open it up more to give yourself something to work to, and properly fill it up with a plasterers trowel, give yourself a nice curve and then sand it down (sponge sanding block, bent into a curve to match). There will be something to stick easyfill to, eventually.. And something can be added if there really is nothing but void there

Or lining paper/paint over it. It'll look a bit worse but mostly people don't look up..