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Can a 110mm strap boss be attached to top surface of horizontal waste pipe ?

The location I am considering placing a the bath in my new bathroom layout is with the bath waste almost directly above a horizontal run of the 110mm bathroom waste pipe running under the floor. This section of 110mm pipe connects the soil stack to a 110mm air admittance valve, thus actually currently has no water running in it.

Due to space constraints it is not possible to get a strap on boss on the side of the 110mm pipe and connect the bath waste to it (structural I-beam joists are in the way) so is it permissible to connect the boss to the upper surface of the 110mm pipe an pipe the bath waste to that ?

Might be slightly noisier ?

Is there a pipe wear issue due to the 110mm "drop" ?

Reply to
Ian_m
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It is perfectly acceptable to connect to the top of the soil pipe.

Reply to
Heliotrope Smith

I see no problem with that as long as your 'horizontal' pipe has a slight

*fall* towards the stack, and not the other way!
Reply to
Roger Mills

I've seen many basin wastes connected into the top of a horizontal soil pipe, so I wouldn't think you would have a problem.

Reply to
The Medway Handyman

Yes - I trust the AAV is not mounted on the end of the (near?) horizontal pipe, but rather, is mounted so it points skyward?

David

Reply to
Lobster

The AAV is mounted on a vertical section at approx 1m above the floor level.

Yes the pipe does slope towards the soil pipe rather than the AAV end.

Only other thing, my brother who is/was a plumber/site manager came up with is don't make the bath waste connection too short as he has met leaking bath wastes where it dropped almost straight into a 110mm pipe and had no give or movement. After about 2 years it started leaking at both boss connection and bath plug as there was probably no "give" in the waste pipework to allow for settlement/movement of both the bath and waste pipe. He fixed by running the

40mm bath waste pipe about a foot along the 110mm waste into a new boss thus allowing some flexibility between the bath and 110mm waste.
Reply to
Ian_m

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