I think it would be way less than that. Maybe around $10k (of course it depends on where you live). Think of it in terms of sq ft. Around here houses go for ~$100/ft2 (fully finished and including the lot)

I guess an average (two-car) garage is about 400-500 ft2. So fully built from scratch, that much square feet finished out would be $40-50k. But you already have the land, the excavation, the slab, the roof, windows etc. All you need is to convert the garage door into wall/windows and of course the interior work. So I'm estimating (really dangerous) about only 25% work remains so about 25% the cost of the full build so about $25/ft2 - say about $10k

So take the average price per foot in your area and try about 1/4 of that.

Of course all of this is just a wild guess. Best to find a neighbor who has had similar work done and of course find a home improvement contractor who can give you a getting started estimate.

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Richard Thoms
President - Top Service Pros, Inc.
Connecting Homeowners and Local Service Professionals
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