Soil pipe and waste routing advice

9 Dec 2005
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United Kingdom

I'm going to run the soil and waste from our bathroom in the loft area and want to check if there are certain things I should or shouldn't be doing.

I've attached a very basic picture showing the routing of the soil and waste pipes.

The soil pipe is 110mm, the wastes from the basin and bath are 40mm. There will be enough drop on the whole run from the toilet to the point it drops to the next floor down for the building regs (it's about 22mm per metre)

The soil pipe will run along the top of the floor from the toilet through the internal wall and into the loft eaves. it passes along the wall near the bath then another bend takes it to where it drops through the ceiling and into the bathroom below (red circle shows where it drops down).

The waste from the sink runs through the wall cavity and into the eaves of the loft space. Here I was going to drop it down into the soil pipe using a boss connection.

The bath waste will pass through the wall and a boss on the side of the soil pipe (just above the centre line to give it a little drop from the bath) will take the waste from there.

Finally, where the green rectangle is will be a Y junction taking an upstanding piece of soil pipe with an air admittance valve on top to vent the stack (building inspector said he was happy with this vent).

Does that all look ok, am I ok to use boss connectors into the pipe for the sink and bath wastes or is there something better for that? I guess using a boss the conections will be at a 90 degree angle to the soil pipe and not a sweeping angle into it!?
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Hi. I'm disappointed that you didn't get any answers as I'm thinking of doing the exact same thing. Did you get an answer elsewhere?

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