Velux insulation collar obstructing reveal

[sgg123]

Hello all,

Feeling rather pleased with myself that I've installed my first roof window. I need to get the trimmers in, and want to allow for a horizontal and vertical reveal and the top and bottom of the window.

My question is that the insulation collar leaves some quite chunky foam internally that I see as an obstruction to this. Do I just force this aside or cut it when fixing the plasterboard as per the Velux technical drawing? Photos below.

Thanks

 

[sgg123]

Got the following back from Velux, which is helpful:

 

[catlad]

Yes you have to put something like a 50mm! piece of plasterboard inline with the frame before you can return to horizontal.
You can use a piece of roofing baton to fasten it to.