Ensure that brandering (38mm x 38mm battens) are fixed onto main trusses no further than 500mm apart and that it is lined up completely level.
Keeping in mind that the ceiling panels should run in the opposite direction of your brandering (same direction as main trusses) measure from wall to wall and cut the ceiling panel to the correct length with a utility knife if necessary.
Through the tongue side of the first panel screw into the batten as close to the wall as possible so that a cornice would be able to conceal the screw. Then screw the same panel on the other side through the groove side. Remember to screw into every batten along the length of the panel.
After ensuring that it is the correct size, clip the second panel with the tongue side into the groove side of the first panel to conceal the screws.
Knock the side of the panel slightly with the palm of your hand to secure close fitment then screw through the groove side of the second panel into the brandering.
Continue this process till the end of the room. If necessary cut the last panel through the length to fit last panel. As with the first panel screw the last panel on the edge as well to ensure that it is secure.
Fit cornice of your choice around corners to conceal all screws and round of your new ceiling.
Lastly, seal off all corners with sealant and clean ceiling with damp cloth if necessary.