Hi Everyone - planning another chimney install for an up north project. I am curious if I can use SuperVent 637-1623 (cathedral ceiling support box) on a non-cathedral ceiling? Asking because this is about 1/2 the price of the decorator ceiling support box and the the attic insulation shield which I installed last time on a different project. Trying to save some money on the install, the attic insulation type is standard rolled insulation not blown in type. No insulation would be above the height of the cathedral support box.