I have attics on each side of my A-frame house, with side 32ft by 6ft space not being used, so I want to finish it off for storage purposes.

I want to finish off the space with plywood and am looking at insulating with r12 batts and use Tyvec as a vapor barrier, and use those foam sheets that let the roof breath above the insulation.

Is this okay to insulate the roof diagonals?

As well in the attached picture there are three 2 x 6" diagonal boards going from the top of the walls down to the middle of the ceiling joists, blocking the passage through the attic room. They look like they were put there to hold up the walls while they were building the house. Does anyone know if those beams are an integral part of the structure? It doesn't seem like there should be any diagonal stresses there now that the house is built and interior walls should oppose any diagonal stress. I would like to cut out those diagonal boards -- without my house falling down

Glenn