Boarding with laminate boards

[LankyPaddy]

I've a loftspace and a ceiling to board out.

Between the joists is PIR insulation, and over the joists is going a thermal laminate board of 40mm insulation + 12.5mm SE boards.

This board seems quite stiff, do still I need to get the board edges lined up on joists (like you have to with single plasterboard sheets?), or is it OK to have board edges unsupported between joists?

 

[LankyPaddy]

To answer my own question, I found the technical data sheet for the boards:

Fixing
Fix boards with decorative side out to receive joint treatment or a skim plaster finish. Lightly butt boards together. Never force boards into position. Install fixings not closer than 13mm from cut edges and 10mm from bound edges. Position cut edges to internal angles whenever possible, removing paper burrs with fine sandpaper. Stagger horizontal and vertical board joints between layers by a minimum of 600mm. Locate boards to a the centre line of framing where this supports board edges or ends.

So the manufacturer says the ends should be supported on the josts.