In the majority of the U.S., it is more cost efficient to buy a home in lieu of renting, but in large cities such as Boston, N.Y., and L.A., the cost of buying a four-bedroom home with a million-dollar mortgage can cost as much as three times the average rent of a similar home. CNBC Real Estate Reporter Diana Olick takes a look at the rent vs. buy debate for these homes.

For the article, Olick looks at the Bock family in Boston who wanted to downsize and found that it was cheaper to rent in the suburbs and it gave them more space. Renting these homes appear to be a growing trend in these areas:

"We're seeing growing demand for rentals in general, and high tides lift all boats. There are definitely more rentals in the suburbs," said Ishay Grinberg, founder of Rental Beast. "People get priced out of the congested downtown areas, and they're getting pushed out into the suburbs, so by default they're renting single family homes."

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