how to install cement backer board behind a bath tub?
operation is same as dry wall
usually regular sheetrock screws will work. just as long as you don't break the backer board to much but you still need to have them slightly countersunk.
if you installing the backer board for tile then what you do first is staple 4 mil plastic sheeting to the studs around the bathtub area over lapping the seams, install the tub. then place the backerboard on the plastic above the top edge of the tub. buy the screws that are made for the backerboard(not drywall screws). after the backer board is installed, use a nylon joint tape also designed for the backer board and then apply thinset to the joints.
you have to pull the tub out, that is disconnect the plumbing - drain - move the tub from the wall and then put in the backer board and then slide the tub back into position and rehook up the drain. Hopefully the drain will move over a half inch to realign again. Otherwise, why behind the tub? You need backer board behind the tile - there is no tile behind the tub. So cut the drywall out that is there now on the wall above the tub and replace it with backer board. Now it is tileable Much simpler, faster and same results.
Cut out the area where backerboard is going to be to the studs. Cut backerboard to size and sink with 5/8 or 3/4 inch drywall screws
