Avoiding “The Bowling Alley” Effect
First, a caveat: unless there’s also a detached garage in the back of the house (typically, off an alley), converting a one-car garage into something else is a non-starter.
That’s because going from a one-car garage to a no-car garage is guaranteed to destroy much more value than it creates.
But, assuming that that’s not the case, is it ever smart to convert a one-car garage into finished square feet?
The short answer: “yes ” provided it’s done well” (actually, that pretty much applies to every prospective major renovation or home addition).
Goodbye, Tuck-Under Garage!
The trick converting a one-garage into finished square feet is the lopsided space: usually, something like 20′ long by 10′ wide.
To avoid creating something with a “bowling alley effect,” it’s important to design the space well, and introduce a lot of natural light.
In practice, the most popular uses for the space are a Home Office, Family Room/Den, or Exercise Room.
Regardless, an added fringe benefit of converting a one-car garage is a no-longer-cold-floor in the Bedroom directly above, especially if it’s uncarpeted (i.e., hardwood).
See, “The Trouble With Tuck-Under’s.”
P.S.: Converting a one-car garage into an extra Bedroom is almost always a mistake: it’s not private enough.