The Oak Bluffs planning board voted 3-0 Wednesday to approve plans for a roof replacement and addition at the Tabernacle, but the approval hinges on clearance from the town wastewater commission.

“They can’t build this if they can’t hook up the sewer,” planning board chairman Ewell Hopkins said during the meeting.

The $6 million project to replace the roof and build a 1,300-square-foot addition on with storage space and 10 bathrooms marks the end of a five-phase restoration effort at the Tabernacle dating back two decades. A site plan hearing opened before the planning board last month. Board members JoJo Lambert and Mark Crossland recused themselves, leaving three members eligible to vote.

The accessory structure has drawn criticism from some Camp Ground residents, who are concerned about the aesthetic impacts.

But on Wednesday, the planning board zeroed in on the wastewater issue.

At a meeting last week, wastewater commission chairman Gail Barmakian, who is also a select board member, cast doubt on whether the project would be allowed to connect to the town wastewater plant. The plant is at capacity and in the early planning stages for expansion.

After discussion Wednesday, the planning board conditioned its approval on some kind of cooperation between the Martha’s Vineyard Camp Meeting Association (MVCMA) and the town wastewater department. Mr. Hopkins said later that cooperation could be in the form of written intent, commitment or a schedule indicating that a future hookup is possible.

“Some level of evidence between the applicant and wastewater that this is a feasible project,” Mr. Hopkins told the Gazette by phone Thursday.

Contacted by phone Thursday, MVCMA president Andrew Patch said the association is evaluating next steps.

“The condition regarding wastewater could obviously be challenging,” Mr. Patch said.

A second condition approved by the planning board requires a third-party review of a stormwater mitigation plan for the project. Mr. Hopkins also worried about excavation posing a threat to nearby trees.

“I really believe that digging that massive hole will be detrimental to the trees,” he said.

The project also still needs a special permit from the zoning board of appeals.