It's not unusual for housing to constitute a given family's single largest monthly expense, but a growing number of people are spending well more than they can afford just to put a roof over their heads. According to a report from Harvard's Joint Center for Housing Studies, an estimated 39 million households can't actually afford their homes. Specifically, one-third of households are spending 30% or more of their take-home pay to cover their housing costs, while almost 19 million families are spending more than 50% of their income on housing.

This data is consistent with a report by the MacArthur Foundation that found that in the three-year period between 2011 and 2014, more than half of Americans made at least one major financial sacrifice in order to manage their housing costs. And that's a problem, because while some folks might compensate for their high housing bills by delaying retirement savings, others will go so far as to cut back on healthcare and food -- things you'd think would be non-negotiable.

Young couple stressed over housing costs


Furthermore, families that take on higher housing costs than they can afford often fall back on credit cards to pay for their remaining living expenses. And when that happens, they risk kick-starting an almost endless cycle of interest charges and debt.

If you're currently spending more than you can reasonably afford to live in your home, it's time to take a step back and rethink that plan. Otherwise, you could end up compromising your finances irreparably.

The danger of overspending on housing

In a recent Bankrate study, 25% of Americans said that they or someone in their family delayed or downright avoided medical treatment because of financial constraints. And while it's true that healthcare can be astronomical, it's also the sort of expense you don't want to skimp on. But if you take on too much house, that's exactly the choice you'll be faced with.

Here's another interesting piece of data from Bankrate: An estimated 37% of homeowners claim that their mortgage payments have had a major impact on their ability to save money. Of course, it's not just homeowners who have a tendency to overspend on housing. In 2015, close to 12 million households spent more than half of their income on rent. What's even more frightening, however, is the fact that by 2025, that number is expected to grow to 15 million.

Even if you're able to swing your housing payments without having to sacrifice your health, or the amount of food you put you on the table, spending too much on a home could seriously compromise your retirement if your mortgage or rent leaves you no leftover cash to save. Currently, about one-third of adults have no money set aside for the future. And since all workers, regardless of salary, need a means of income outside Social Security once they retire, those who don't save risk sentencing themselves to a cash-strapped existence for what could be several decades' time. Worse yet, those who overspend on housing and ignore their nest eggs may wind up in the unenviable position of never managing to retire at all.

Keep your spending in check

So how much is too much with regard to housing? As a general rule, you should never spend more than 30% of your take-home pay on housing, but that doesn't mean you can feel free to blow that amount on your rent or mortgage payment alone. Rather, that 30% threshold is also meant to encompass the peripheral housing costs you'll face, including property taxes for homeowners and insurance, which both homeowners and renters need.

Also, while some financial experts will tell you that homeowners need not include traditional maintenance in that 30% limit, in reality, you're much better off keeping your total anticipated housing costs to 30% of your income or less. This way, you'll have some wiggle room in your budget for when an unplanned expense pops up.

Are there exceptions to this 30% rule? Maybe a few. If you happen to live somewhere with cheap public transportation and you have excellent health coverage through your employer, then you might get away with exceeding that 30% limit ever so slightly. But you should never, under any circumstances, spend 50% of your earnings on housing, no matter how low your remaining living expenses might be.

Finally, just because many people can safely spend up to 30% of their income on housing doesn't mean you shouldn't aim to keep that number much lower. The less you spend on a home, the more flexibility you'll have to cover your other living costs, and the more opportunity you'll have to save money for the future. And what you may sacrifice in convenience or square footage, you'll more than make up for in financial security.