Mixed-Use Financing Options with Pre-existing Commercial Tenants?

[Katie Sax]

I’m looking into buying a mixed-use property. It was once residential with a main house (1800 sq ft) and small back house (750 sq. ft). The main space is used as an office for a non-profit organization and currently has an active lease set to expire Dec. 2025, but lease doesn’t have to carry with the sale. I’d like to house it, using the back house as a rental and living in the main house. It wouldn’t require any construction to revert back to a house. We would just need to remove the desks. 

My lender says it can't be done residentially due to the commercial lease being current. She says if there wasn't tenants, it wouldn't be an issue. But, the appraisal will have to consider the current use. My question is, if I intended to use the main house (over 51% of sq ft) as the primary residence, is there a way to use FHA or any residential lending? Would I have to do commercial due to the lease?