In the past, people who were struggling to pay rent and utilities were measured by the 30 percent rule: If you spent more than 30 percent of your income on housing costs, you were considered to have housing cost burdens.

Over the past decade, that measure has become outdated. Now, one in four renters, or 10.1 million households, spend more than half of their income on rent and utilities, according to “America’s Rental Housing: Meeting Challenges, Building on Opportunities,” a new report from the Harvard Joint Center for Housing Studies (JCHS) released this week. Another 26.2 percent of renters spend 30 percent to 50 percent of their income on rent and utilities.

It’s not just the sheer amount of their income that people are willing to spend on keeping a roof over their head. It’s also a matter of who is seeing a bigger slice of their income go for housing over the past half-decade. While three-fourths of renters in the bottom quartile facing severe housing burdens, more lower middle-income and middle-income renters are facing moderate burdens, as well. The number of lower middle-income renters paying 30 percent to 50 percent of their income for rent and utilities jumped from 38 percent to 56 percent, while the number of middle-income renters in the same situation jumped from 10 percent to 23 percent.

“The affordability problems are increasingly affecting Americans of more than just modest means,” said Eric S. Belsky, managing director of the Harvard Joint Center for Housing Studies and an author of the study.

A Growing Problem

The affordability issue has been rising for the past 50 years but intensified over the last decade with the “triple whammy” of rising rents and utility costs and falling renter income. In the 1960s, only a quarter of American renters faced cost burdens, and only 12 percent faced significant burdens. By 2009, half of American renters faced burdens.

“We not just have a consistent, decades-long struggle for renters to afford housing, but that has been exacerbated by this [financial] crisis,” says HUD Secretary Shaun Donovan, who gave the keynote address at the Harvard event.

With so much of their income going to housing, renters are often forced to make concessions in other areas. “To spend half of your income on housing means that you have very little to spend on anything else,” Belsky says.

Chris Herbert, director of research for the Harvard Joint Center and a co-author of the study, said burdened families have 37 percent less to spend on food, 52 percent less to spend on clothing, 52 percent less to spend on healthcare, and 71 percent less to spend on transportation. “When you talk about low levels of spending as it is, this has a profound impact on a household’s well-being,” he says.

Rental Strain

In the past years, apartment owners have seen rent growth around the country. That trend is expected to intensify in the coming years with little new supply being introduced and new renters, whether 20-somethings or foreclosed homeowners, entering the market. While good news for landlords, these trends could push rental affordability out of reach of many, particularly in America’s high-cost cities. “In the near term, the affordability issue will worsen,” Herbert said.

Further straining the issue is shrinking supply. The Harvard Joint Center Report says that since the mid-1990s, more than 700,000 rentals with subsidies tied to them were lost from the subsidized housing stock. Nearly 12 percent of the low-cost rentals existing in 1999 were lost from the housing stock by 2009. And rental housing stock is older than ever before, with a median age of 38 years. “We can’t keep the housing we already have,” Herbert said. “It’s a drain on affordable housing.”

With rising land costs and other issues, adding new supply is getting harder than ever. In the 1970s, the country added 300,000 subsidized units a year. In the past five years, it’s down to 75,000 units. In the past five years, the number of renters went up by 4 million, creating a noticeable gap.

And much of the affordable housing out there (like foreclosed single-family homes) isn’t in areas near job centers for many renters. “We don’t have enough rental housing in the right places,” Donovan says. “The places hardest-hit were the least close to transit and schools.”

With the federal budget tightening and local and state budgets strained, speakers at the Harvard event admitted it was becoming more difficult to find affordable rental housing. For instance, one-quarter of people eligible for rental housing assistance receive it, according to Belsky.

Nearly across the board, every speaker at the Harvard event acknowledged that it would be more difficult for the government to produce more housing. That could become an even greater reality if changes to the tax code put the Low Income Housing Tax Credit (LIHTC) in jeopardy (Donovan says there will be “an urge to play defense” with LIHTC, which is the third-most-popular corporate deduction).

In some cases, speakers suggested that the best course of action would be for the government to loosen regulations and make it possible for affordable developers and renovators to do their work. But Donovan insisted that the government could play a role in helping solve affordability issue with things such as financing housing programs and establishing income curves that reach more workforce house.

“We must think bigger, go farther, and take a series of steps,” he says.