As home prices soar in Seattle, purchasing property is becoming a distant dream for many renters, regardless of how long they've lived in the city. Loftium, a recently launched startup, wants to make buying a home more affordable—with a catch: Homebuyers have to rent out a space to AirBnb.

Loftium's launch comes on the heels of Seattle City Council members considering a $10 a night tax on AirBnb hosts and limiting how much space hosts can rent out.

In the meantime, Loftium is partnering with Umpqua Bank to help 50 prospective Seattle homebuyers afford a downpayment on their new digs. The amount of Loftium's assistance depends on the neighborhood customers are hoping to buy and how long they agree to rent a room to AirBnb. Loftium would keep a chunk of the monthly revenue from the rented room, GeekWire reports.

For example, a customer looking to buy in a popular neighborhood could receive $20,000 toward her down payment, agree to rent a bedroom for somewhere between 12 and 36 months, and give Loftium 70 percent of the monthly revenue generated from Airbnb, retaining the other 30 percent for herself.

Customers wouldn't be penalized if their AirBnb room underperforms, GeekWire noted.