[RedBear]

Hey, Friends.

I have a few gaps in the ceiling at the edge between some drywall and hardibacker. Should I fill this with just drywall mud or something like caulk? Put in underneath the seam tape?

See picture as an example.

Red

 

[CplDevilDog]

Drywall mud and tape will be fine

You may want to trim away the paper and remove the cracked sections of green board. Run new screws where the board is not broken.