Advice needed to insulate an existing block wall from the exterior
The local parish hall has a 40′ x 44′ addition with exterior walls of 8″ concrete block and a bow truss roof/ceiling that was built in the 60’s. On the interior, there is no additional wall build-out or insulation, just exposed block. We are planning on insulating the exterior walls and adding blown in cellulose to the existing fiberglass roof insulation after air sealing all penetrations.
My question has to do with insulating the exterior walls. Since there are rooms, interior finishes, electrical and forced hot water baseboard heat on the interior, we are planning on insulating from the exterior. The plan to date is to add two layers of 2″ XPS rigid insulation, weather barrier, strap vertically and re-side to the existing fascia and soffit which will go from 10″ to 5″ deep. Existing double glazed vinyl windows will require new trim and aluminum flashing. There are a few areas on the building where grade extends above the floor line, and will have to be dealt with separately.
Is the the best way to solve this situation? Is there a need for the weather barrier other than a secondary protection for moisture and insects?
Climate Zone 5, Western Massachusetts
Thanks for your help.
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