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Remodeling bathroom in old house. Water always backed up in the tub. I've replaced the waste lines and pitched them properly. The original line from the tub went under a double floor joist and across 3 others. Should I do something different?

Michael Karas
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fixit24
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If the drain is sloped correctly per your local building codes (mine state for drain pipes under 2 inches the slope be 1/4 inch per foot) and it is connected to a stack of the proper size (usually no smaller than 1 1/4 inch pipe) then your drain and trap should operate trouble-free. Also be sure the distance from the trap to the vent or stack is correct (in my county any run over 40 feet will need a larger diameter vent).

As far as running pipe through framing members and joists you must be selective on the location to drill a hole through. This depends one the size of the joist and if it has existing openings already drilled into it. If you plan to use a non-drilled joist one opening (again, depending on the size of the joist)is safe. Be sure not to deviate from the starting slope.

ojait
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  • It's a bit more complicated than just "one hole is safe" -- there's a good answer on this site that [explains the rules for holes in joists](https://diy.stackexchange.com/a/10661/157). – gregmac Jan 10 '16 at 06:18
  • The original drain line runs across 3 floor joists that are notched at the top and then turned 45 degrees down and turned 45 degrees to go under a double joist. If I make another turn up to the tub/shower drain on the other side of the double joist, will that create a kind if natural p trap? I'm kind if worried about the tub/shower draining properly with that design. This was the original design. – fixit24 Jan 11 '16 at 02:51
  • This is a very good site with great information. My v – fixit24 Jan 11 '16 at 02:56
  • I have seen this. Its great. Since the natural path of the drain line runs into the double joist. So it turned down and turned 45 degrees again to go under the double joist. Then up to the tub/shower p trap. I don't think you can notch that double joist. – fixit24 Jan 11 '16 at 03:11
  • That will depend on the location of the notch or hole in the joist and also the size. – ojait Jan 11 '16 at 17:31