Overcrowded with a growing staff, the NCAA headquarters in White River State Park will double in size via a $35 million expansion to be under construction by next spring.

The executive committee of the National Collegiate Athletic Association agreed this week to go ahead with the project, which was planned under the administration of the NCAA’s late president, Myles Brand, who died Sept. 16.

Bob Williams, managing director of public and media relations for the NCAA, said Friday that the 130,000-square-foot expansion will include offices and meeting space.

The new structure will be a separate building on the west side of the current 116,000-square-foot headquarters, linked by a second-floor bridge.

When complete, the NCAA campus at 700 W. Washington St. will include three buildings: the existing national headquarters built in 1999, the proposed addition to open in mid-2012 and the existing 30,000-square-foot Hall of Champions and convention center.

The proposed expansion roughly doubles the office and meeting space for the national association staff.

Williams said the current building was constructed for about 350 employees and was expected to contain the operations over 20 years. However, in less than 10 years, there now are about 500 working for the NCAA.

That includes about 70 people in the Eligibility Center, which is in a warehouse-turned-office-building near 16th Street and the White River, about a mile from the main building.

No fundraising campaign is expected for the building project. Williams said it will be financed with about $2 million a year that is currently budgeted for rental space and other savings.

The glass-and-brick exterior design of the four-story building is intended to complement the existing building.

Much of the ground floor will have meeting and conference rooms and related facilities, so that the national organization’s meetings can all be held here.

“In an effort to curtail costs, we are setting a goal of holding 95 percent of the association’s meetings in Indianapolis. We have all sorts of committees and other groups, and they have met in locations all around the country,” Williams said.

“Bringing all of that to Indianapolis is a cost containment. But in order to do that, we have to ensure that we have adequate meeting space here.”