Best Way to Fill Large-ish Joint Between Walls and Ceiling?

[schismatic]

I’ve made some slight measurement errors and ended up with a relatively large joint/gap between the top of my Hardiebacker board and the ceiling (see pic). The joint is 12mm at its widest.

With the other walls, the joint was much smaller (~2-4mm) so I’ve been able to caulk those, but I’m not sure just caulking is the best approach for this bigger gap, so I’d like some advice on how best to address it. Should I just try to caulk this up, or is there a better technique to use?

The joint is on the same wall as the shower unit will be installed on.

Cheers.

 

[J Sid]

tile adhesive will be fine

 

[Boggs]

Is there a horizontal fixing at the top?

Might be better to add one if you can.

 

[On one]

Nothing to worry about. But if you already had it.......squirty foam?

 

[Waluigi]

Is there a horizontal fixing at the top?

Might be better to add one if you can.

I’m glad it wasn’t just me that thought that.

Hardiebacker is very strong in the 12mm version so probably be OK.

Filler wise, not much will add any strength unless you go for a giant bead of Gripfill or other such like Building adhesive.

Usually you would have a top plate on a stud wall, whether that be timber studs or metal.

 

[Blunt Tool]

Is your screws sitting proud of board? I would use a countersink bit and get that sorted, just makes life easier as does a top rail and fill in imo

 

[schismatic]

Thanks for all of the suggestions guys, I’ll have a think about what is best.

Is your screws sitting proud of board? I would use a countersink bit and get that sorted, just makes life easier as does a top rail and fill in imo

Yeah they’re slightly proud, I can’t get them to drive any further. So what your suggesting is to take each one out, drill a countersink pilot and then put them back in?

 

[Blunt Tool]

Thanks for all of the suggestions guys, I’ll have a think about what is best.



Yeah they’re slightly proud, I can’t get them to drive any further. So what your suggesting is to take each one out, drill a countersink pilot and then put them back in?

Yes when using the 10mm and above boards I drill pilot and countersink before screwing find it a lot easier.

 

[Waluigi]

If you don’t have or want to buy a countersink bit then a 12mm masonry bit will do the job. Possibly even a 10mm.

 

[schismatic]

Ok thanks. Is it absolutely necessary to do? The majority do sit proud, however only very slightly. Wouldn’t a relatively thick layer of adhesive cover them, or are there problems caused by that? (Apologies, I’m not clued up on the implications).

I only ask as there are literally 100 screws to do and because the majority have done into metal studding (gypframe in new build) I am worried about disturbing the ‘grab’ that the screw has made into the metal. I don’t want to risk my current, very sturdy walls unless I have to.