My house was built in 1976. I recently replaced the range hood and discovered that the piece of rectangular ducting that runs inside the cabinet is not connected to the outlet vent on the outside of the house. It effectively vents into the attic space under the roof. That attic space is not used for anything, and in fact it is not even accessible.
My contractor quoted 650$ to install the duct, which is not surprising given the difficulty accessing that space.
What are the pros and cons to installing the duct vs. leaving it as is? Out of curiosity, was it considered a standard practice in the 70's to skip a 10-foot section of ducting and let the cooking fumes dissipate in an attic space?