Cost Segregation and no cap gains

[Zachary Gray]

looking to purchase a duplex to live in one unit and rent out the other in the greater Boston area. I intend to live there for 2 years and then rent it for 3. Having lived in it for 2 of the last 5 years i would be exempt from capital gains upon sale, negating the need for 1031. If I improve the quality of the unit and do cost segregation for bonus depreciation upon purchase, I gain the benefit of the larger tax write off in the short term and still pay no cap gain taxes upon sale at the end of the 5 years. Just wanted to determine if this is allowed?