Re-locating bathroom - soil / waste advice

[rob7475]

Hi,

I'm renovating an old one bed back to back. My plan is to turn the bathroom into a second bedroom and split the current bedroom to create a bathroom as the room is massive.

The new bathroom will have no external walls so I've got a bit of a challenge with running the soil pipe to the front of the house. My plan is to run the 110mm between the joists to the front of the house before joining the stack. However, the joists are only about 8" so I'm going to struggle to get the 18mm drop on the pipe. As there will be a sink and bath discharging to the same pipe, would I be OK if the drop is a bit less than 18mm?

My other option is to drop the pipe below the joists into the kitchen and box in - this would create upto 3 bends on the way out though - would that be worse than having a slightly lower drop?

Another part of the plan is to run a vertical soil pipe in the store room next to the bathroom before the pipe disappears under the floor and fit an AAV due to the length of the run.

Also, where would be best to connect the sink and bath waste into the soil pipe - I've attached a picture so you can get an idea of my plan.

Thanks

 

[Newboy]

Absolute minimum fall is 18 mm/ 1m, recommended fall is 44 mm / 1m.

Your run looks to be approximately 5 m so you need a fall of between 90 mm & 220mm. With a 200 mm joist depth and a pipe diameter of 125 mm (allowing for fittings), you only have 75 mm to play with.

Not recommended!

 

[Lower]

How high are the ceilings downstairs? Any chance of lowering them by a couple of inches?

 

[rob7475]

How high are the ceilings downstairs? Any chance of lowering them by a couple of inches?

Cant drop the ceiling as the window and door frame are almost at ceiling height.

If i take the pipe into the kitchen, i can go below ceiling level and box it in to get the required drop. This would mean creating a couple of bends in the pipe though - is this ok with toilet waste?

 

[Hugh Jaleak]

Bends are frowned upon in the vertical sections, but if in the 'horizontal' run, are less of an issue. Just make sure rodding access is provided, (preferably outside for obvious reasons!), and ensure there is adequate fall on the pipe and you should be ok.

Wastes, either connect with bosses as required, or look at a manifold at/below floor level.