Abstract: The present invention relates to a ceiling tile unit comprising a tile body made of mineral fibre material, a surface layer and a guide. The tile body has a front side, a rear side and at least one side edge, and the surface layer is arranged on said front side of said tile body. A groove is provided in said rear side of said tile body dividing said tile body into a first tile body section and a second tile body section. Said guide is adapted to form a fold guidance for inclination of said first tile body section in relation to said second tile body section by folding about an axis parallel to the longitudinal direction of said groove. The invention further relates to a method for forming a ceiling tile unit.