Toilet waste pipe

[sotal]

I'm putting together some sketches ready to get quotes from some builders in order to have a dormer built to house an en-suite.

I'm trying to envisage any issues before hand.

Luckily there is a toilet below the area that we want to put the en-suite so I'm hoping that they will be able to somehow tap into the pipework below.

My only worry was the main toilet waste pipe. The current toilet downstairs has a pipe which goes out of the back of the toilet and then turns 90* to the left, then has a short straight section, then another 90* bend to the left, then a very short straight section (virtually nothing) then another 90* bend down into the ground. This slightly complex arrangement comes from moving the toilet a few years back. The easiest place to join into would be the short section after the first 90* bend. My worry is that if you then used the flush upstairs, it would basically go straight out of the toilet, then it would have a 3m drop and hit the pipe at the bottom only a few inches from the toilet downstairs - would the force of it falling send it into the other toilet?

If it is a problem I would need to get it dug up outside and a vertical pipe up the outside, but as it is a dormer that would need to be at the side of the house which would mean a bit more digging up to connect it to the sewer.

Also if the interior option would work, would I need a vent on the top? If so am I right in thinking that there are solutions now that give you a vent inside rather than having to go through the roof?

Thanks

 

[dilalio]

Let your builder guide you. If he's good he will know the correct method... or his plumber will.

 

[Hugh Jaleak]

A lot of factors involved here, it may not be straightforward, but without looking at the current setup, and checking distances, it's impossible to say. Worst case scenario, you wont be able to tap into the existing arrangement, and a new stack will have to be put in, with an underground run to a suitable connection point on the existing drain.

An Air Admittance Valve may be able to be used as opposed to an open vent, but again, that depends on the existing setup. Ultimately, Building Control will have the final say on what they'll permit.