Bonding narrow cement board to under-side of soffit

[phatboy]

Hi all,

I need to attach some 60mm x 1200mm pieces of cement board to the underside of a wooden soffit (I'd like to screw them but the boards will surely crack at this width)

I'm wondering if (cheap) Gripfill will hold small sections like this in position, whilst it goes off? Or if anybody can suggest an alternative product?

Thanks

 

[23vc]

Gripfill probably would hold it, but how long it’d last would be my concern, plus danger if it fell off etc.
existing soffit would be fixed to rafters/carcassing, if you can find them then screw into it

 

[phatboy]

Gripfill probably would hold it, but how long it’d last would be my concern, plus danger if it fell off etc.
existing soffit would be fixed to rafters/carcassing, if you can find them then screw into it

I thought that stuff held forever?! As I just want to fix 60mm wide strips of cement board along the front edge of the soffit for rendering over, screwing through it would destroy it.

Maybe I should be swapping for tile backer, as that will also take render and won't fall apart with screws? Hmmm..... just want to use up offcuts I have around.

 

[Wayners]

I'd use polymer grab.
But you going to want to add something mechanical to hold it long term.
Bead or clip around edges.
You can get channel strips for soft boards and other things you maybe able to use to adapt to hold.
Can't say I like the idea Vs doing it properly