TOWNSEND -- A new, 180,530-square-foot building is the preferred choice for improving the high school in the North Middlesex school district and qualifying for partial reimbursement through state grants.

The option was one of three chosen to present to the Massachusetts School Building Authority by the North Middlesex Regional High School Building Committee at a meeting and community forum held at the high school Monday.

The current estimated project cost for the option is $89.5 million, based on a construction start date of March 2015. The committee is required to present a preferred solution and two alternatives to the MSBA, said Sue Lisio, a committee member and Townsend selectman.

The other two choices are a larger new building, 192,005 square feet, with an estimated cost of $95.2 million and an addition/renovation project with a total of 190,656 square feet at a cost of $80.1 million.

The committee was required to present a renovation/addition option to the MSBA, said Robert Templeton, chairman. All the options reduced educational programs. The MSBA recommended a smaller school with roughly 175,000 square feet to serve a projected student population of 870.

The committee's preference for a 190,000-square-foot school was discussed with the MSBA, Superintendent Joan Landers said. Using their recommendations, changes were made including reducing the number of classrooms from 29 to 28, eliminating one of two large group instruction rooms and altering proposed labs.

Templeton spoke in favor of asking for approval for the larger building. "We are asking for a grant from the MSBA," he said. The authority can choose to partially fund a smaller amount than what is requested. "We still have a lot of work to do. I say we try and get the people of these towns the best option."

Some towns do have nicer facilities than what North Middlesex may eventually build, said committee member Heidi Messing, but the district cannot compare itself to a wealthier place like Carlisle. "We've got to build something the towns are going to approve," she said.

If the project is approved by the MSBA, between 57 and 63 percent of allowable costs would be reimbursed to the district. But If the building exceeds 180,000 square feet, the additional costs might not be approved for reimbursement, Messing said.

Although the MSBA recommended 175,000 square feet, the school's special education program space was not reduced in the plans. The increase in size is defensible because it is very important to create in-house programs rather than send students out to other schools, Landers said. The out-of-town practice is both expensive and not educationally sound.

The majority of the committee voted for the $89.5 million new building. Two members, Templeton and Gary Shepherd, voted for the more expensive option. All members voted to include the addition/renovation option as required by the MSBA.

The cap for construction costs was raised to $79.3 million as a result of what has been learned after meeting with consultants, doing studies, comparing options and preparing schematics, said Peter Collins of Heery International, the owners' project manager. The previous cap of $70 million was set 12 to 18 months ago when the committee first began work.