I recently had a conversation similar to this one with my realtor.

The reason is because the home had a garage conversion a long time ago.

If it's zoned as a SFH and only has one APN lookup your local laws on 'Accessory Dwelling Units' it's entirely possible the conversion was unpermitted and you'll get in trouble/have to rip out the 2nd unit if any code inspector finds out about it. 

In these types of conversations you will learn what to look for.  

Usually it's a garage conversion, so you lose the appeal of a garage.

Can you recommend if you have any good architect in queens, NY area. we just had conversation with one person in universal design const mgmt LLC. i would preferred if you guy recommend someone. 

Here are some recommendations for you:Find and connect with other BP members that are in your area: http://www.biggerpockets.com/meetSet up keyword alerts to be notified of the topics that interest you: http://www.biggerpockets.com/alertsRead Beginner’s Guide: http://www.biggerpockets.com/real-estate-investingCheck out BP Podcasts: http://www.biggerpockets.com/renewsblog/category/podcast/If you wish to tag someone in the conversation on the forum, type @ followed by their name and then select the name of that person which should appear below the comments box.

Here are some recommendations for you:Find and connect with other BP members that are in your area:http://www.biggerpockets.com/meetSet up keyword alerts to be notified of the topics that interest you:http://www.biggerpockets.com/alertsRead Beginner’s Guide:http://www.biggerpockets.com/real-estate-investingCheck out BP Podcasts:http://www.biggerpockets.com/renewsblog/category/podcast/If you wish to tag someone in the conversation on the forum, type @ followed by their name and then select the name of that person which should appear below the comments box.

It was great meeting you at the Gaithersburg meetup earlier this month, and I look forward to many conversations with you in the future.  

Good tenants are attracted to maintained properties.The other side of the conversation is on the purchase/acquisition cost.