Aug. 24–The Hotel Commonwealth is planning to expand, less than a year after new owners bought the Kenmore Square property.

The owners plan to add 96 more rooms, event space and parking by building on to the back of the facility, which is currently a 23,000-square-foot parking lot that backs up to the Massachusetts Turnpike, according to plans filed with the Boston Redevelopment Authority.

The new building would be no higher than the current building and consist of 134,000 square feet.

It would make the Commonwealth a 245-room hotel.

The hotel deferred comment to Denver-based Sage Hospitality, which did not return messages seeking comment yesterday.

Hotel Commonwealth was credited with revitalizing a stretch of Kenmore Square when it replaced 14 rundown buildings and officially opened in 2003. The trustees of Boston University sold the property to Sage in December in a deal that also included leases for retail and restaurant tenants.

The hotel includes popular nightspots Eastern Standard and Island Creek Oyster Bar.

The filings don’t provide a timetable for when construction will start and wrap up. But officials plan to submit documents to the BRA next month.

The six-story, $70 million hotel was mocked for resembling a plastic Lego structure when it was unveiled.

It had been hyped as French Second Empire-style architecture. Hotel officials shelled out $4 million to give the facility a facelift shortly after.