Hi,

I’m trying to reroute my bathroom DWV lines in advance of raising my house (to avoid a repeat of the seven feet of water we had several years ago). The existing layout, left on the attached diagram, has a vertical stack that continues underground to the street. I want to redirect the main to travel under the floor joints (right of the diagram) to the front of the house, where it would then travel vertically to the underground line. The cast iron main under the house and underground is 70+ years old and would be covered by a new concrete floor under the raised house.

To the point, would the proposed layout be acceptable? Venting is a concern but also the fittings I have in mind, which are: 1) 3” x 3” x 2” elbow with low heel, 2) 3” tee wye, and 3) 3” tee wye with cleanout.

Thanks for your insights.

Hi Tom...

In my area the side inlet elbow wouldn't fly. In other areas of the country the side inlet elbow is OK. In my area, the tub must connect below the inlet to the toilet.

Check with your local plumbing inspector and see if a side inlet elbow is allowed when WET VENTING the toilet and tub using the lavatory vent. If not a 3"x2" wye may need to be substituted for the side inlet elbow.

If the end cleanout you proposed in your right diagram will not be accessible then opt. to eliminate the cleanout and dead end the run of 3" into the toilet.

Otherwise, as long as wet venting is allowed in your area, all looks very good!

MARK
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Mark,

Thanks very much for taking the time to review my diagram and comment on the situation.

Wet venting isn't a concern, but the fitting you mention could be. However, my illustration is misleading, reflecting my drafting skills. The elbow in question (#1) is 3 x 3 x 2 with a low heel, i.e. the 2" connection is at the rear of the bend, if that was not obvious (or matters). To make the tub connection, I would have to add an 1/8 turn elbow beyond the elbow.

Of course, if the toilet must connect above the tub inlet then my primary objective of raising the lines would largely be defeated. With the DW lines running under the joists, instead of vertically to the underground main, I was hoping to start the slope as close to the joists as possible to account for the slope toward the front of the house. With two sanitary tees and an elbow extending from the lavatory drain/vent to achieve the necessary arrangement, the main will hang well into the space below the joists (and I would undoubtedly hit my head - repeatedly).

I'll contemplate alternatives.

Thanks again,

Tom

From the category of 'old dogs learning new tricks', I found the answer to my question about low heel elbows. They are intended for vent connections in vertical applications. My ignorance knows no bounds.

Tom..

Check out the pic. Below...

If you add a 3"x2" wye on the horizontal as drawn below you should be all set.

Let me know...

MARK

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Mark,

Thanks for the reply. Your design is among those I had considered, but I was concerned about exceeding the maximum trap-vent distance for the tub. Before crawling under to take the appropriate measurements, perhaps you can clarify an important point. In your layout, would the trap-vent distance be considered the distance from the front of the trap to the wye or to the wye plus the distance to the vent stack? The difference is only a few inches, but the latter measure could exceed 6'.

Thanks again,

Tom

Hi Tom:

As you can see in the diagram below, the 6'0" distance is the distance between the vent and the weir of the trap. You should be all set using the wye... :)

MARK