Moving back home with mom and dad might be the fastest way for someone to save enough money to make a down payment on a home, according to Zillow Group, a real estate monitoring service.

The catch is that mom and dad better be ready for long stay.

Because housing prices are so high in San Diego, it takes a typical renter nearly 28 years to save enough for a 20 percent down payment, the company said.

Bunking with the parents can cut that to about 15 years.

That’s assuming a median monthly rent of $2,730 and a median home value of $591,400, which is lower than some other real estate organizations have estimated.

Nationally, Zillow Group reported that it would take a typical renter slightly about eight years to save for a 20 percent down payment, which could be cut to about five years by living with parents.

No word on how parents feel about any of this.