I need to seal a shower tray but the tray is 0.5"-1" away from the wall at the back (the wall facing you as you walk into the cubicle). I have filled the hole with plumbers mate putty and now I'm not sure what to do next.
I could fit a long thin strip of WBP ply over the gap along the length of the back wall so that it over hangs across the tray by half an inch or so, then I could seal / stick it to the walls / the shower tray with no more nails or silicone or something where the ply meets the tray, then tile over the ply and seal with grout. Does that make sense? I assume nothing will stick to the putty I have used. Would someone walk me through the process of what I should do / not do to seal a gap like this?