Underestimating the hidden costs associated with buying and owning a home, including the ongoing responsibilities of maintaining it, is the No. 1 millennial homeowner frustration.

It's a common mistake, experts say, and it can be a costly one.

You need to know that you can truly afford to both buy and own a home, and to get the full picture, you need to do more than simply compare your current rent payment with the potential mortgage payment, Daryl Fairweather, chief economist at real estate site Redfin, tells CNBC Make It.

"Do a full check of all finances," Fairweather says. "A lot of hidden fees come with owning a home that you might not consider immediately." That includes the insurance, property taxes and closing costs — which can be2 to 5 percent of the home price.

Those kinds of hidden costs even tripped up real estate mogul Barbara Corcoran early on. "When I bought my first home I showed up at the table to close without the closing costs," she told CNBC Make It. "Thank God I was able to borrow it from the very nice seller or I couldn't have closed on the place."