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You realy need the dimension of wall to center of waste for the basin your fitting
a true first fix is fitting it all and then removing which is what used to be done especially on high end fit outs
and still is done if theres marble involved
i always prefer to core a hole straight thru the wall and into a hopper head or gulley if i can, then use an adjustable bottle trap inside, in my oppinion thats the best way to do it, but if it must be hidden in the pedestall i wouldn't bother without having the basin on site, or you will look like a total idiot if you get it wrong!!!! not so bad if its too far back to the wall! but it can be a disater if its too far forward!!!!
Stick the waste In the wall lower than the basin then use a telescopic waste so you don't have to get it bang on otherwise as close to the wall as pos with a 90at the top into a trap. If not set the basin up, if you haven't got it moan at the client, first fixing without the gear on site is annoying, if the customer changes their mind or buys something foreign you can't do standard measurements
Reply to the thread, titled "First fixing basin waste" which is posted in UK Plumbers Forums on Plumbers Forums.
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