<prompt> Human: Background: Weve lived in our house for 15 years in Denver highlands historical area. The neighborhood is undergoing a boom. According to Zillow the value is about 350K and our current mortgage is about 190K after refinancig it last year at 3.5The house next to ours is a Denver Square and has been recently purchase by someone who wants to renovate it. He doesnt have much yard on either side but he wants to build a drive way and garage. Our house sits on the alley but has a yard about as big as our house. Both lots are 50 by 102.15.The new neighbor wants to purchase a 12 by 75 area of land so that he can put a garage and a small drive way next to our property.How is this done? what should we be thinking about? Does this affect our mortgage, value of the house.We would like to do some improvements to our house new garage, expand the house etc and this may be a way to pay for it. edit: thank you for the responses.  <response>: First off, have either of you looked into zoning in your neighborhood? Chances are the minimum required lot size is 5,000 square feet, and minimum road frontage is 50 feet. If thats the case you wouldnt be able to subdivide the property changing property lines is considered a subdivision in most jurisdictions without a variance from the zoning board, which your properties most likely wouldnt qualify for since both properties are already developed although it unfortunately tends to come down to the whims of the zoning board. Generally, if you go and talk to someone in the Planning Department theyll give you an overview of the process, and if youre looking for relief from regulations like a variance, some idea of how likely it would be to get it granted. 