Probably from the base of kerannumi (through the idea of mixing clay and water); earthenware, i.e. A tile (by analogy, a thin roof or awning) -- tiling.
KJV: And when they could not find by what way they might bring him in because of the multitude, they went upon the housetop, and let him down through the tiling with his couch into the midst before Jesus.
NASB: But not finding any way to bring him in because of the crowd, they went up on the roof and let him down through the tiles with his stretcher, into the middle of the crowd, in front of Jesus.