Beyoncé Knowles was reportedly spotted house hunting without Jay-Z.

The superstar couple are said to have been experiencing a rough patch in their marriage.

And according to the New York Post, Beyoncé scoped out a 4,045 sq ft, $21.5 million apartment in the Chelsea area of New York City last month with Jay-Z nowhere in sight at the viewing.

“She was very quiet, as if she was looking on the sly,” a source told the outlet.

Rumours first surfaced of marital troubles after Beyoncé's sister Solange was filmed attacking Jay-Z in an elevator in May.

There have also been allegations about the rapper being unfaithful, which have never been proven.

The pair currently resides in an 8,309 sq ft home in Tribeca with their two-year-old daughter Blue Ivy, and it is claimed Jay-Z would be unwilling to part from the property.

“I can say with certainty that Jay is not downsizing,” the insider declared.

It is unconfirmed whether Beyoncé’s alleged viewing was for personal or business reasons.

But it is rumoured she may be considering moving into a new flat with Blue Ivy.

“There’s no way a $20?million apartment is for her mother or her sister. That would be wildly unlikely,’’ the source said.

The singer and rapper are currently on their joint On The Run Tour. While she caused raised eyebrows by changing the lyrics of one of her songs to seemingly accuse Jay of not treating her properly, they have since put on a show of togetherness with Jay evening kissing his wife on stage.