Financial pressure is mounting not only on the 800,000 federal workers who are going without pay during the partial government shutdown, but on anyone who aspires to own a home, according to Zillow.

The unpaid workers—380,000 workers are furloughed during the shutdown and 420,000 essential employees are working without pay—are in many cases struggling to pay their mortgage as the shutdown approaches three weeks, according to the real estate website.

Impacted federal workers who own homes pay about $249 million in monthly mortgage payments, Zillow estimated.

The website noted that the HotPads website has estimated that affected federal employees who are renters pay about $189 million for housing each month.

But the shutdown is also impacting anyone who is aspiring to own a home, the website said.

"The Federal Housing Administration is operating with limited staff and warns that endorsement of loans may be delayed," Zillow said in a press release. "That could mean some loans don't close, as that decision depends on the flexibility of individual lenders, leaving buyers unable to complete their purchase."

Zillow pointed out that many lower-income and first-time buyers opt for FHA-insured loans because they often allow for smaller down payments and lower credit scores than conventional loans.

An estimated 3,900 mortgage originations are processed each day for loans backed by federal agencies, and as many as 39,000 may have been delayed so far by the government shutdown, Zillow said, adding that FHA won't insure reverse mortgages or home-improvement loans during the shutdown.

Loans backed by Fannie Mae and Freddie Mac, two independent agencies that insure the vast majority of mortgages, may also run into delays, according to Zillow.

"Many federal employees rely on each and every paycheck to cover critical expenses, including housing. In many parts of the country, housing affordability is already stretched and a single missed payment can begin the long process toward foreclosure or eviction," said Zillow senior economist Aaron Terrazas. The shutdown “also could have a significant impact on the overall housing market if it continues to drag on and furloughed workers who also are would-be buyers get cold feet in the absence of paychecks."