I currently live in a house that has an attached two car garage, plus an additional two car detached garage. We have a great room, but not a seperate family/playroom for my daughters toys, and the “great room” ends up with all the babies toys all over the place. I’m thinking of converted half of the attached garage into a family room. It would add approxiamtely 240 square feet to our living space, and still leave a one car attached garage and the two car detached garage (with attic).
Would this be a wise investment? I’m estimating that the conversion will cost approximately $10,000. Also, I live in NJ and my house is approx. 3000 square feet. Any info or advise would be greatly appreciated.

It would not add much value. It will add approximately 240 sq ft x between $55 and $65 a sq ft in value which is $14,400. Then subtract loosing the garage at around $5000. So it will add around $9,500 to the current value of your house.
With the way the market is going do it because you want it. Not because its going to add any value to your property.
I am a NJ certified state appraiser.
Also the numbers are estimates.. the majority of the pricing depends on your neighborhood and the comps in the area.
What are the other houses like in your area? If you make your house significantly different than the others in the area, contrary to popular belief, it will not increase the value of your home proportionate to the money you spend on the renovation. Is the detached garage close enough to somehow make it an attached garage, by creating a covered, enclosed walkway? If you could do that, and in your area most houses have only a 1 or 2 car garage, than I would convert the entire space rather than half the space. It opens up your current options and your future potential. Good luck.
if im not mistaken try to call a local home apraisor and ask them what they think on what you should do in a market like this one, an appraisor tends to cost about $300-$600 per inspection, its true that almost any addition will add equity but dont expect to sell your house within a year or two, you would be beter off saving your 10,000 dollors and paying that interest off each month as fast as possible, that is what i would recomend though.
happy hunting
First, doing anything now would not necessarily add value. Second, taking away a garage would defiantly would subtract from the value.
Any upgrades made to your hose will up the value of it.