Soil pipe fall / routing

[Philip Ingles]

I am considering re-routing an internal soil pip from an ensuite WC. The pipe has to find its way from the middle of the house to the opposite side wall at the back. My proposed route includes a section where it follows the slope of the stairs (about 45 degrees).

But I read somewhere that the fall should only be quite gentle - between 1/50 an 1/20. Although that might be the ideal slope, is it not possible to safely include a much steeper slope? Does that encourage blockages? Or is there another reason why it must not be done?

Thank you.

 

[noseall]

you can include a steeper slope if you wish. after all most svp's are vertical! gentle slopes are encouraged to prevent the solids splattering up the sides of inspection chambers and to obviously, negate a deeper than necessary dig.

adding too many bends in a drain run without an access hatch can be an issue.

 

[Richard C]

Without knowing the layout, pipe lengths, number of changes in direction etc it’s difficult for anyone to give you meaningful advice. I would suggest you read Part H of the building regs. & possibly speak to your LABC or you may find yourself breaching at least one or more of the regulations & if BC are involved in compliance inspection, they will just reject it; also a little curious as to know why you need to re-route!

Any change in direction, particularly more than 45 degrees, must have access form one end or the other for clearance of blockages; the max length of a branch pipe into the main stack which feeds the foul drain, which effectively sounds like you re-route, is 6m for a W/C; there are also rules regarding offsets in the wet portion of the stack & any connections you make to it &, again, this sounds like your 45 degree re-route. Increasing the gradient of the foul pipe beyond that recommended also encourages the water to flow much quicker leaving the solids behind &, with a W/C, it’s pretty obvious what that means!

 

[Philip Ingles]

Thanks for the replies, that's very helpful.

Currently the soil pipe in boxed in but runs at shoulder height along a hallway and staircase and it is ugly and intrusive. I am thinking of changing it because I think I can see a better route which is out of the way. I would reconnect to the current routing before the pipe leaves the house and joins the soil stack outside - so no change there.

Again thanks for the help, any further advice is much appreciated.