My home was built in 1971. There is a brick fireplace that runs up the entire wall. The mortar is cracking and breaking in chunks(about 1" thickness) where the fireplace attaches to the wall. I decided I should chip out all the mortar and just put new mortar in; however, one side isn't really that bad. Do you think I should take the mortar out of it to anyway? I was told that mortar won't stick to mortar. Has anyone had to repair between a brick fireplace and wall and did you like the outcome? Any suggestions? Picture attached. Thank you.
It looks like you have movement. I like using quarter round at joints like this. I would make some measurements of the gaps--they could have happened long ago but a picture of a tape measure and the date saved or printed off and saved inside a cabinet close will help you see if it is getting worse.
It could be rot. Bad flashing around fireplaces and some rotten studs or header across the fireplace are not uncommon.
It could be ants, termites or beetles having their meals on the structure.
It could be soil movement.
I listed them in the order I have found the most often over the years. If it doesn’t change in the next 6 months check it in a year. If there's no change again it's just settling that happened in the past.
Ed Beal has some good suggestions. Personally I don't like using moldings to hide things like that. I prefer to create a lap, thus eliminating the issue.
If you can clean out the mortar sufficiently from the surface and behind the brick, simply skim your drywall with joint compound along and behind the brick, then paint. Leave the brick with the appearance that it floats or laps over the drywall, rather than joining to it.
If the gap bothers you, some gray rope caulk tucked back in there would eliminate the deep shadow and approximate the color of the mortar.
I would encase it in trim. I would try to use something that matches maybe the doors or other vertical trim in the house. You are going to have to cap it at the top and possibly bottom.
You can go quarter round as Jack mentioned but this is going to look rough and out of place and quite possibly tacky. You need to make the trim decision look like it was made on purpose, not purposely hiding something.
I would not use caulk as the one gap is so big its just not suitable. I would also not mud the area because of the movement - not only may it crack soon but the mud might flake.