2:45 p.m. EDT May 17, 2015  Annual rent increases across the U.S. last month outpaced the rise in home prices for the first time in at least five years, a milestone that should spur the sluggish home-buying market.

The median U.S. rent climbed 4% in April from the year-ago period to $1,364, according to real estate database Zillow. That's the biggest jump since March 2013.

Home sale prices, meanwhile, increased 3% to $178,400, rising less than 4% for the second month after 24 straight months of stronger gains. As a result, rents grew faster than home prices for the first time since Zillow began tracking the data in 2010.

"For those renters that can scrape together even a modest down payment, qualify for a loan and find an affordable home to buy, home ownership will look increasingly attractive," says Svenga Gudell, Zillow's head of economic research.

Multifamily construction fell off a cliff after the housing crash and financial crisis in the late 2000s, pushing up median rents by 15% since 2010, Zillow figures show. Building activity has picked up the past couple of years, but it hasn't kept up with rising demand.

With job growth reaching a 15-year high of 3.1 million in 2014, many Millennials living with parents or roommates since the recession are finally moving out and into apartments. In the first quarter, the number of occupied housing units in the U.S. surged by 1.5 million over the previous 12 months after such household formation languished at less than half that level from 2007 to 2013, according to the Census Bureau. New renters accounted for all the gains.

The national rental vacancy rate sank to a 22-year low of 7.1% in the first quarter, Census data show. Cities such as San Francisco, San Jose and Denver have seen double-digit rent increases.

The home-buying market, meanwhile, has struggled since last year after recovering smartly in 2013. Tight credit standards continue to limit the entry of first-time home buyers who are critical to a healthy market but comprise just 30% of all purchasers compared to a normal 40%.

Lawrence Yun, chief economist of the National Association of Realtors, expects the share of first-time home buyers to rise to 33% by year-end, in part because of the financial benefits of home ownership vs. renting.

One caveat: rising rents will limit the ability of many apartment dwellers to save up enough money for a down payment, especially with wages growing more slowly than rental costs, Gudell says. That, she says, will slow the shift to home ownership.