Help and advice on toilet waste pipe location. Pics included

[Richard C]

(1.18 Document H) Branch pipes up to 40mm diameter joining branch pipes 100mm diameter or greater should, if practicable, connect to the upper part of the pipe wall of the larger branch.

Which implies that you can...[/quote]

You can’t just quote that single clause in isolation as proof that it will work. There is still a requirement to maintain a minimum of 25mm in all traps under all conditions & for the provision of ventilation to prevent siphoning as & where necessary; if you follow good design practice it’s never a problem!

I’m bored with this, it's like sticking pins in your eyes; Chris you’ve got mine & a couple of other opinions, decide for yourself; or better still phone your LABC & ask them; but if you do, post back what they say!

 

[Kristoff28]

Many thanks for all your replies.

I have decided to go as per the original pipework and take the bath/whb
seperatly to the outside branch.

Will i be ok to merge bath (40mm) and sink (32mm) into one then take
to outside branch using 40mm pipe ???

Thanks

Kris

 

[Richard C]

The maximum length for an unvented branch is 3m for 40mm pipe & 4m for 50mm so this will dictate the diameter of your branch waste & you must have a fall between 18-90mm. If you connect the sink waste into the bath branch you should fit an anti-siphon unit on the sink or you stand a big risk of siphoning the sink trap when you empty the bath. If you use 50mm as the common branch (which looks like yours was originally) you may get away with it; your original sink trap looks fairly deep but who knows; IMV it doesn’t comply without current regs. without an anti-siphon unit fitted & if your installation is being inspected, the BI may reject it.

I’m sorry but we seem to be going around in circles here; have you looked at the link to the BR’s & the design guide I posted you? The Hunter guide figure 3, page 8 in particular has examples of exactly what you want to do! Did you phone your LABC for advice & what did they say?