Simple question re shower trays and traps

[cjard]

First fixing the waste plumbing and I have the shower tray available. it will sit directly on the chipboard floor and I have access to the underside. If the hole in the tray is 90mm diameter and the depression around it into which the drain face sits is 110mm diameter, how big of a hole should I be looking to drill in the floor so I can mount the trap? I suspect it should be larger than the hole in the tray, as I think the trap will need to butt up to the underside of the tray?

thanks guys

 

[cjard]

bump..

 

[denso13]

You are correct but you really need the actual trap to determine the correct hole size. You will also have to allow for the trap outlet in the hole in the floor (probably).