WESTPORT — With the finalized schematic design plans for a new middle and senior high school still not completed, the Westport School Building Committee voted to delay the town’s submission of the $80 million project to the Massachusetts School Building Authority by a month and a half.

School Building Committee co-chair Dianne Baron urged the submission schedule be pushed back by six weeks at the outset of the committee’s Sept. 6 meeting, saying members needed more time to finalize a few more building details, and make final adjustments to the total project budget.

The site and building plans were due to be completed and submitted to the MSBA Sept. 14, but that deadline has been changed to Nov. 9. The building committee hopes to have a complete set of plans and total budget plan ready for a Nov. 1 joint meeting of the Select Board and School Committee.

If that schedule is maintained, the project should get reviews and approvals from MSBA facilities subcommittees by the end of November. The full MSBA board would issue building reimbursement figures at its mid-December meeting, setting a firm figure for a vote on the local financing of the project at a January special town meeting.

Still to be settled by the building committee are the final choices of some interior and exterior building materials, and the increasingly controversial relocation of the public tennis courts behind the former Westport Middle School.

As the project stands, estimates place the construction costs of a steel-framed, two-story combined middle school and high school of about 183,000 square feet at slightly more than $61 million. Site development expenses, including an estimated $8 million to demolish the old middle school and dispose of hazardous materials found there, bring total project costs to more than $80 million.

Some members have suggested cost-cutting adjustments also need to be made to site and building plans to make the project more acceptable to taxpayers. An extra $1 million in anticipated costs for the relocation of the tennis courts, for example, drew lots of attention from building committee members at the most recent meeting.

Baron said there were a few “open issues” to be resolved to refine the final plans, and proceeded to guide members through a long discussion of the proposed height of hallway and classroom ceilings at the early September meeting. Architectural plans called for 8-foot-high hallways and 10-foot high classrooms, part of an economy effort to reduce square footage and overall building costs.

Baron has also asked for firm numbers on projected operating costs for the new school to help the building committee make final decisions on building materials and energy-saving efforts.

Dan Tavares, the school district’s owner’s project manager, said the ceiling heights were considerably lower than those being installed in most new schools, and argued for more headroom throughout the proposed school facility.

Two School Committee members serving on the building committee also advocated for higher ceilings, with an 8-inch increase in height for both floors eventually approved on a 6-3 vote. Lead architect Jonathan Levi was in opposition, suggesting that the proposed ceiling heights were perfectly adequate.

The architect said raising the ceilings and building heights would add perhaps $450,000 to the overall building costs. The move was part of his plan to create “a very compact, very efficient building,” he said.

Levi was asked to work with a design subcommittee to finalize the choices of exterior materials, and find a new location for the tennis courts, so projected building costs should be firmed up by Oct. 18.

The building committee seemed confident that all of the remaining work could be done in the six-week window created by the vote to delay submission of plans.

“I think it’s very important that you’re taking the time necessary to get this right,” Tavares said of the timetable decision. But, he warned, the school district cannot miss the Nov. 9 submission deadline without risk of losing the chance for state reimbursements.