Tanking shower enclosure - how do I deal with this issue?

[markharro]

Almost finished the backer board and then will tape before using a tanking roll on product. Can I leave this hole "open" or does it needed sorted and if so how? The reason its there was to fit the cement backer board as the pipe that feeds the outlet to the right pushes out a bit.

 

Thanks

[Beau]

Some of the tanking paints also come with a roll of mesh tape. I would fill the hole with a low expanding foam, cut flush, mesh tape and then apply the tanking paint. I'm only a DIYer so take this advise with a pinch of salt haha

[markharro]

Thanks v much. Be good to get some more input on this as well.