16x16x1/2 beaverboard ceiling tile

I'm looking for a source to replace 16x16x1/2 inch beaverboard ceiling tiles. The tiles must have tongue and grove ends and no pattern, just a plain finish that can be painted white. I'm not concerned about the material, since new beaverboard tile is probably unavailable. Diminsions are important. I need roughly two dozen tiles minimum to replace damaged tiles in the ceiling of my church. Other than new tile sources, is there a source for reclaimed beaverboard tile?

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