Laura Ricketts, a co-owner of the Chicago Cubs, and her partner, Heidi Grathouse, have filed plans with the Village of Wilmette for a new mansion to be built on the 1.2-acre lakefront site they bought two years ago.

Thanks to the lot’s lakeward slope, the home will be two stories high in front facing Sheridan Road but three in the rear facing Lake Michigan. According to the plans for the six-bedroom house, which were filed May 17, the roof will open to a widow’s walk; several secondary spaces that extend from the main house will have green roofs; and the east (lake-facing) wall of the house will have at least 40 windows, in assorted shapes and sizes.

Drawings show a stucco and limestone façade topped by a slate roof. The front of the house will have a motor court surrounded by an elbow-shaped four-car garage and storage, and the main entry to the home will be framed in limestone columns.

Inside, there’s a relatively formal main floor, with the living room, family room, and kitchen facing the lake; there’s a dining room, an office, and other rooms on the interior. The second-floor master suite has a large bedroom with a bow of windows out to the lake, as well as an office and library. There are four other bedrooms on the second floor, and over the garage is a 50-foot-long space designated the “hangout.”

The size of the home is difficult to calculate, because below-grade spaces are not always counted, according to John Adler, Wilmette’s community development director. The plans, which I looked at on Monday, call for a large below-grade portion of the main house that would contain a family room, a wine room, a theatre, and other spaces; a below-grade wing extending toward the lake would have a swimming pool and assorted rooms. The aboveground space totals about 9,500 square feet, says an architect with Morgante Wilson, the firm that designed the home. (The architect asked not to be identified by name because of the firm’s relationship with the client.) The final square-footage count is pending, Adler said; the project is now in zoning review.

“We wanted to blend the house into the site,” the architect said of submerging so much space. The drawings show a wing that contains the pool and other rooms stepping down as it approaches the water and terminating in what’s designated the “lake room.” The architect adds that the widow’s walk is designed in part to showcase the Bahai’i House of Worship across the street.

Ricketts paid $6.5 million for the site in June 2010, according to the Cook County Recorder of Deeds. Demolition of the home that was on the property began in mid-April. The architect says the old house is “being deconstructed, and we’ll recycle all the materials we can. It’s very important to our clients to be as green as possible.”

The construction cost is difficult to estimate, because of variables such as the green elements and the swimming pool. The architect would not comment, nor would Adler, but based on the size and scope of the house, it’s clearly a multimillion-dollar project.

According to county records, Ricketts and Grathouse have not yet sold their home in Edgewater. I could not reach them for comment. Two Ricketts brothers, Tom and Todd, live within six blocks of the lakefront site in Wilmette; their homes are at opposite ends of the same block, though neither is more than one-third the size of what their sister has on the boards.