I bought a house last year that had a permit pulled for an enclosed garage.
Working garage-door opener is functional, but rarely if ever used today.
This area is now used as a very large utility room, xtra fridge, storage,
ect.

I am interested in converting most of this area into a small 3rd bedroom
(currently house has 2 beds/2 baths). Is this feasible and at what point
would it be cost-effective (in long-term valuation of home, home is 45 yrs.
old, concrete block&stucco, and has about 40 years of remaining life
expectancy according to insurance papers)?