I haven't noticed a big bump in Philadelphia. How about where you live?

The housing bust horror flick is now giving way to a very unwelcome sequel: a big squeeze on the cost of renting.

The number of renters paying more than half of their income towards rent has hit record levels, according to a new study by the Joint Center for Housing Studies (JCHS) of Harvard University.

Rental affordability is a critical issue for seniors, who live on fixed incomes and already are coping with low yields on their savings, fast-rising healthcare expenses and stagnant Social Security benefits. Yet the struggle with affordability is found most often among low-income Americans; JCHS found that 75 percent of renters in the lowest quartile of income are spending more than half of their income on housing. JCHS also found that lower-middle class renters also are having trouble finding affordable rental housing.

For example, 33 percent of renters with annual income of $14,500 to $30,000 are facing “severe burdens” in finding affordable rent. And the problem is growing most rapidly among demographic groups traditionally less likely to have affordability problems, including younger households, married couples with children and renters with some college education.

“These are astounding numbers,” says Eric Belsky, managing director of JCHS. “If you are spending half of your income on housing, you have very little to spend on everything else.”