Moving toilet soil pipe

[compton]

Hi everyone!
I am moving a toilet across a room. I have had conflicting opinions from two plumbers about soil pipe routing. I upload a dodgy sketch to explain.
In the circle is the current toilet and vent pipes which are boxed. I need to remove the toilet and all the pipes in that wall. For the new toilet, I want to drop the pipe in between the rafters, do a horizontal run of 2.3m up to the opposing wall where the stalk is. Then a small drop with long radius elbows, and in to a horizontal 1m run in to the stalk. The vent then would come from above where the toilet joins the stalk, and up in to the loft, with an air admitance valve. Is the small drop between the two horizontal segments an issue? I could/will put an access point there.
The other option I want to avoid would be running the pipe form under the new toilet straight in to the stalk, along the ceiling of the garage, but I lose head room and will look horrible...
Thanks for your advice and knowledge!

 

[sircerebus666]

What are the conflicting opinions from the two plumbers?

 

[compton]

One is saying there should not be a drop in the middle of the run, and that it should go straight across in to the stalk (under the rafters, on the ceiling garage).

 

[compton]

He did not have a good reason for it as far as I could see it... Not sure if he just could not be bothered adding two more elbows

 

[Newboy]

He did not have a good reason for it as far as I could see it

Building Regs Part H 1.16

 

[compton]

Thanks for pointing that.
"Bends in branch pipes should be avoided "if possible". Where they cannot they should have as large a radius as possible"
Technically it is possible to pass the pipes under the ceiling across the garage, but it is far from ideal... I Think I will do it with large radius bends against the wall, with access point. I can always change the pipe from underneath...
Is this something that requires building control?

 

[Newboy]

https://www.labc.co.uk/news/when-do...r-bathroom-need-building-regulations-approval

 

[Ian H]

I’m sure that would work, it no different to a small dropshaft into a manhole.

I’d be more concerned about that floor, be careful you don’t fall off the toilet into the garage!!

 

[compton]

Thanks! I agree, it is like a small dropshaft, although technically not ventilated.

 

[Hugh Jaleak]

If the stack is currently vented, (i.e. open to atmosphere), I'd be wary of capping it with an AAV, you may find you have problems.