Petra Academy, a private school in Bozeman that focuses on "classical, Christ-centered" education, is planning to build a new $7.5 million facility on the city's west side that will allow the school to more than double its enrollment.

Petra has submitted an application to the city seeking to build a 44,500-square-foot building on a roughly 20-acre lot off of Cottonwood Road between Babcock Street and Durston Road. The site is just south of Bronken Fields next to the Valley West Subdivision.

"The new school will be built to accommodate 226 students - pre-kindergarten through 12th grade - with 16 students per class," said Susan Beth Breuner, development director for the school and parent of a fifth-grade student.

Petra finished up the school year with 91 students, and Breuner said she expects there will be more than 100 students this fall.

"We are out of room," she said.

Petra Academy is currently located in the Genesis Business Park off of Discovery Drive in south Bozeman. Petra opened its doors in Bozeman 15 years ago and was previously housed in a warehouse building, then two rented houses.

Plans for the new school include building seven elementary and seven secondary classrooms, a 288-seat theater, a gymnasium with bleacher seating and a 3,000-square-foot atrium, according to Petra's application to the city.

Petra students currently walk over to Grace Bible Church for gym class and have bounced around to borrow different theaters. Breuner said Petra hopes to make the new school's gym and theater available to the public.

School officials hope to have the new building ready for students in September of 2011.

"We don't foresee any roadblocks because we've had such good communication with the city," Breuner said.

The city's review process has just begun. The proposal went before the city's Design Review Board on Wednesday.

Amanda Ricker can be reached at aricker@dailychronicle.com or 582-2628.