Need Advice on Routing of Horizontal Drain Line on 2nd Floor

Old 05-22-05, 08:42 PM
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Question Need Advice on Routing of Horizontal Drain Line on 2nd Floor

I have a question on routing of the 3" toilet drain on a new bathroom project. The best layout requires a long horizontal run with several turns.

I'd like to get some perspective on whether or not this routing is advisable and if it will be prone to problems. I'm trying to keep the piping within the joist spaces (2 by 8s)

The layout would require 30' of horizontal piping. It also requires 3 horizontal 90 deg elblows. The first 22' can be sloped at .25 in per foot. However, due to structural obstructions, the last 8 ft will have a slope of less than 1/8" per foot.

A shower, tub, and lavoratory would also tie in to this drain line. The lavoratory would tie in before the first elbow - within 2 ft of the toilet. The tub and shower would tie in within 8 ft of the toilet - between the first and second elbow.

The destination of this drain line is an existing cast iron stack.

To access the elbows for cleanout, I'd have to cut holes in the ceiling of the first floor.

No bathroom or plumbing exists today on this floor.

I have read several books, but can't find much perspective on this issue.

Thanks for maintaining such a great forum!
Old 05-22-05, 11:01 PM
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This probably isn't the answer you're looking for, and it's very hard to access the situation w/o being on-site. But my gut tells me that a good plumber could find a better route. Have you ever opened a clean-out in a drain that's been in use for a while? You really don't want it in the ceiling, especially if the drain is full of sewage; you'd snake from above, pull the toilet if you have to.

Much better to find a route that is less prone to needing a snake in the first place.

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