I'm in the middle of a bathroom renovation, which will be tiled with large format porcelain tiles on both the floor and walls.
I put 1/4" HardiBacker on the floor, laid on top of a bed of thinset as per the installation instructions. I used the "BackerOn" coated screws that home depot sells with the HardiBacker sheets. I was not happy with how the screws tend to split or fracture the hardi, mostly around the edge even when holding back 3/4" from the sheet edge.
When I started putting 1/2" backer on the walls I switched to hot-dipped galvanized ring shank nails, 2" long, using a framing nailgun to set them. I dialed back the drive depth to leave almost all nails either flush or slightly proud of the surface, and then I tapped them flush with a hammer. I had some that broke the surface of the board though.
After completing almost the entire bathroom I then was told that I should have used roofing nails, not framing nails, due to the size of the head. What I'm concerned about is that the backer board might pull through the nail heads of the smaller diameter framing nails. They are full-round head. not clipped head, but still much smaller than a roofing nail.
Am I justified in my worry? Should I go back over and augment the nailed boards with some screws?