Bath tub drain slow - How does water flow uphill

[Jef]

My mother's house is a chicago bungalow probably about 60 yrs old, with a main floor and basement. The bathtub has always drained slow - but recently it pratically stopped. The drain and pipes run under the floor and can be reached from the basement.

The trap is about 6 inches beneath the floor. The pipe coming out the 'j' runs upward at a slight angle for about 2 feet. It connects into a 45 degree elbow which takes the pipe upward about another 4 -inches where it levels off and runs about 6 feet before going into the main drain.

My question is: Could the upward angle of the drain pipes be the cause of the tub draining so slow.

One other question: Some of the pipes run through pre-cut holes in the floor joists. (I guess they did this when the house was built). My nephew made some additional cuts in the joists to make the pipe easier to remove.
Is it safe to cut spaces in the floor joists?

Thanks

 

[Mike Swearingen]

Water doesn't flow uphill and standard drain systems work by gravity flow, so the answer to your first questions is YES. This drain line should slope 1/4" per linear foot from the trap to the main drain line with no upward angle whatsoever.
That's what is causing the slow drain, and it will plug up easily.
It needs to be re-plumbed from the trap to wherever that 1/4" slope connects properly, even if all the way to the main drain line.
The answer to your second question is NO, floor joists should not be cut (unless they're properly reinforced). They will weaken over time, causing floor sags.
I would lower the drain lines below the floor joist level, and sister new joists from end to end onto the ones that have been cut.
Good Luck!
Mike

 

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[Jef]

Jef

Mike, thanks. Been caught up with other things. Thanks again.