If a shul has carpeting does one have to put a cloth under ones knees while kneeling on yom kippur? What about having a cloth for the head? What are the sources?
For a stone floor, there is an obligation to place a separation between one’s head and the floor (there is no need for a separation between knees and floor).
For a non-stone floor, and certainly where there is carpeting, there is no obligation to make a separation.
For the obligation of placing a separation between head and stone floor, see Taz 131:15, Magen Avraham 22, Mishnah Berurah 44. Refer to Pri Megadim M.Z. 14.
For a marble floor, many authorities writes that the obligation of a separation still applies. See Magen Avraham 20, Mishnah Berurah 41, Shevet Ha’Levi 1:23; see alao Mateh Ephraim 621:14. Some write that a cement floor has the halachah of a stone floor.