Cement Board Joins and Caulking

Hi all,

Two questions for this...i'm putting Cement Fibre board as an external protection\clad onto a small building and as we can simply prime it and paint it (as opposed to putting a render or further cladding on it) i've never installed this stuff but looking at various instructions and videos it seems some users put these on flush to each other and some put these on with a gap so firstly do i need to leave a gap between the boards or push them flush together and secondly as i'm not rendering anything on top of this what kind of caulking for gaps as it looks like you use silicon but i "would" like the joins not to show so didn't know if a sandable caulk would be best (if i can use that of course)

Thanks

Something like this, I'd leave no gaps and squidge some of this in the joint as you go and sponge the joint flush. https://www.toolstation.com/toupret-murex-exterior-filler/p72427

The edges are not tapered, so can't be filled, reinforced and sanded flat, so joints will show.

So we'll HAVE to either apply render or cosmetic battens as i've seen ?

You'll need to consult the manufacturer. All materials move to some extent, so you'll need to seek the manufacturers guidance. But even the timber battens or frame you intend to fit these too will move, so that needs to be factored in too.

Righto, i'll give them a call. Thanks