180 degree bend from toilet outflow

[gollum]

Hi ,
I just wanted to ask for peoples experience/advice.
I am installing a toilet under the ground floor stairs. The 6 metre 110mm soil pipe will go from here to the back garden under the floor hanging from the joists. Only issue is the direction the toilet will face(towards the garden) means it needs a 180 degree bend directly underneath it to the 6 metres soil pipe as I said it then leads to the garden .

I just want to know if it could mean problematic blockages if I fit a 180 degree bend on the toilet outflow to go underfloor. ?
Also do you think these corrugated flexi bends are a bad idea and best to stick with unflexible bends.?
Is it best to go for 25mm drop every 1 metre on the 6 metre horizontal run, whats the minimum drop i can manage ?
Regarding ventilation has anyone found the devices that remove odour by sucking air from the toilet and pushing into the soil pipe a good buy , can you recommend ?
Many Thanks for your help.
Steve.

 

[motorbiking]

Is there any chance of rodents getting in under your floor? They like to eat the flexi-connectors.

 

[stardanny]

Use proper soli pipe bend. You may need a AAV above wc pan spill over.

Daniel.

 

[Hugh Jaleak]

I will assume it is a straight run under the floor from outside to where the pipe will turn upwards to meet the pan. (I also hope you're connecting to a drain in the garden... ) Don't see a problem, as all ground floor pans require 2x90° bends if the drain is under the floor. Provided the distance from the crown of the WC trap to the invert, (bottom edge), of the drain is less than 1.3m you can make a direct connection to the drain.

For the fall, 1:40 is recommended, although you can push it to 1:100 in extreme circumstances, but I'd be wary of that. Use proper bends, flexi's are generally disliked by the trade for various reasons.

 

[gollum]

Hi , thanks for your contributions everyone.
HaHa, Yes Hugh I am connecting to drain in the garden .. But let me do some digging this weekend to expose the invert then I can post a drawing. !
Rgds. Steve.

 

[gollum]

Basically after digging today I have realised I can connect straight into my soil outside with a Y once I make a hole in the external brick wall. (see the first pic).
But there are some issues. The existing vertical soil needs a new connection as they put some kind of rubber webbing webbing around the joint & covered with cement

And of course as you can see in the pic above this is a fracture and if you look closely at the first pic there are fractures around the flanges. So I think this all has to be replaced ?
Also going back to the drawing I will make the drop 1:40 so that 25mm per metre. And I will use solid bends rather than flexi. I aim to get all the bits in push fit and obviously I need to bed all of the new pipe on pea shingle,
1. I just don't know if I should expose all of this pipe back towards the manhole to check it (extra work) or if I just join the new pipe I buy to just after the Y you see in the pic ?
2. how deep should pea shingle be, 2 inches ?
3. what should I do about ventilation in the toilet room. ? I know I can get a fan but that means extra ducting under the floor probably to the external vent you see in the pic. I have heard about these devices that somehow use the toilet to suck in air and expel it into the soil pipe. Is this not the way to go , anyone used this solution ?

 

[Hugh Jaleak]

Chances are, the more you disturb, the more damage you'll find. If you're planning on staying in the house, I'd be looking at replacing the damaged pipework from the junction up to the house at the very least. You can join onto the soil pipe without an issue, and I'd replace the gulley with a 'Bottle Gulley', connecting the rainwater pipe via a back inlet, and the waste through the grid to avoid any future damage to the house wall.

Peagravel, 2" under the pipe then surround the pipe to protect it once correct fall has been achieved. No big lumps or bricks/stones in the initial layer of backfill either.

Fan, can you mount something on an external wall and just duct straight through to outside?

 

[gollum]

Hi
Ok understood, So I need this one http://www.screwfix.com/p/floplast-back-inlet-bottle-gully/12051.
But if you look at my pic you see the level by the drain is too high because it goes over the DPC. Now I aim to lower and not put back the crazy paving but just put shingle down. Problem is I will then not have much shingle above the soil pipe , so I either use a smaller diameter pipe from the rainwater downpipe up to the Y branch (but I imagine this is not allowed ?? ) Or I have to see if I can install the 110mm pipe a little deeper but maintain the 1:40 gradient. Also I think you mentioned on other thread that clay was more robust if you have a shallow depth. ? Or is it best to cement over pipe then put shingle on top of that. ? So many questions , sorry

3. Fan - cannot install in wall as a terraced house and this toilet is under stairs. Any experience of these devices that fit into toilet ?
4. Do I need a rest bend http://www.screwfix.com/p/floplast-double-socket-rest-bend-87-5-110mm/12719 for the soil pipe coming down.? That pipe only runs vertically for one storey then it goes inside a small extension roof horizontally then continues vertically up to roof .