converting a SFR to a duplex

[Corey Bodnar]

I currently own a 4/2 and considering using 2 bedrooms and part of the garage to convert it into an ADC or duplex. This would make it 2/2 and a 1/1. My main question is will this kill my home value? short term it will allow me to cut my mortgage in half and id be able to move later and have 2 units to rent.