Cutting ventilation openings in double-walled construction

[LexChix]

I buried this question in an earlier post, and it is....

How do I cut ventilation openings when there's double-walled construction with insulation? I already have the inside sheathing attached. Should I cut the windows now on the inside sheathing and try to match the window opening size on the outside wall before it's attached to the coop? Or should I add the insulation and outside wall and cut through all layers with a reciprocating saw?

To see photos of the coop so far, please go to my previous post. Thanks so much!!

 

[jetdog]

I would cut it on the outside first, it's more important to get the outside hole right not so important on the inside.