The Zoning Board of Appeal on Tuesday approved plans by the Conservatory Lab Charter School to add a cafeteria, gym and new classroom to its K1-to-grade-2 school at 131 Hancock St. in Dorchester.

The school is planning to use the roughly 6,000-square-foot addition to its current 19,000-square-foot building as a benefit for its current students, rather than for expanding the number of students, its attorney, Donald Wiest, said. The school has a separate school building for students in grades 3-8.

The school, open to students across Boston, was founded on the belief that musical education should be intergral to academic pursuits," Weist said.