Hi Nigel - the best way to fit our ceiling panels is to use screws. Our panels are tongue-and-groove, so we'd recommend you screw through the tongue/groove part; then, when you fix the next panel along into space, it will cover over the screw head and hide it. You could also use adhesive but this would be more awkward as you'd have to support the panel and keep it in place while the adhesive keys (it's not a contact adhesive). It'd be preferable to use full boards wall to wall as it would look much better, but if not you could use a joint strip in between for a better finish than the exposed cut edges butted up to one another.